fO.-Z.H.2.'i^ 3Frottt tl|p Htbraru of J^rnfrsBor Smpmln Irwkinrtbgp Jiarftflb l^q«patl|P& btf l?tm to tljf ICtbrarg of Prtnrfton Sliirolagiral S>cminary Sec La^ A1, Ak, Digitized by the Internet Archive in 2011 with funding from Princeton Theological Seminary Library http://www.archive.org/details/handbookofpsychoOObald /^^■^ ^0^^^^ ^OT S4 1922 *] HANDBOOK OF PSYCHOLOGY '^^'^ Jcuscs autX %nUlUct / JAMES MAEK BALDWIN, Ph.D. PROFESSOR OF PHILOSOPHY IN LAKE FOREST UNIVERSITY NEW YORK HENEY HOLT AND COMPANY 1889 Copyright, 1889, BY Henry Holt 'S. of the. 34 PSYCHOLOGICAL METHOD. Human Ilind, li-v ; Jouffroy, Nouveaux Melanges, pp. 223-279 ; Boaillier, Lepiincipe vitale, ch. xxv ; Enctjc. Britann., Qih. ed., arts. Metaphysics, PTdlosopluj. On the relation of mind and body : Carpenter, Mental Physi- ology, ch. i-ii ; Brentano, Psychologie, pp. 100-130 ; Ladd, Physi- olog. Psychology, pp. 633-667; Taine, Intelligence, pt. 1, bk. 4; Volkmann, loc. cit. jj 14-16 ; Waitz, Grundlegung der Psychologie, p. 100; Maudsley, loc. cit. ch. ii ; Groom Robertson, Mind, in. p. 24 ; Lotze, Microcosmns, bk. 3, ch. i-iii. On child psychology : Perez, First Three Years of Cliildhood, and Child from Three to Seven Years ; Prayer, The Ilind of the Child; Darwin, Mind, ii. 285; Kussmaul, Untersuchungen iiber das Seelenleben des neugebornen Menschen. On animal psychology : Romanes, Mental Evolution in Ani- mals, and Animal Intelligence ; Espinas, Animal Societies ; Lindsey, Mind in the Lower Animals ; Vignoli, Saggio di psicologia coni- parata ;Wedtz, Grundleguny der Psychologie, pp. 139-201 ; Lewes, Problems, 3d series, p. 118; Lubbock, Ants, Bees, and Wasps; Schneider, TJiierische Wille ; Perty, Revue Philosojyhiciue ; Wundt, Essays, vii ; Rabier, ch. xlviii ; Perty, Die Seelenlehre der Thiere ; Lotze, Microcosintis, i. pp. 556-561. On race psychology : Zeitschrift fitr Volkerpsychologie (through- out) ; Ribot, German. PsycJiology, ch. in ; Spencer, Descriptive Sociology ; Waitz, Ifuturvolker ; Bastmn, Menscli in der Geschichte ; Mill, Logic, bk. 4, ch. v ; Lazarus, Das Leben der Seele, v. 567 ; Maine, Village CommunitieJi, and Early History of Institutions. Histories of]}sychology are : Siebeck, Geschichte der Psychologie (incomplete) ; Harms, Geschichte der Psychologie ; Hamilton, His- torical Notes on Reid (in edition of Reid's works) ; Volkmann, loc cit., historical notes throughout ; Ribot, English Psychology, and German Psychology of To day. CHAPTEE III. CLASSIFICATION AND DIVISION. § 1. Three Geeat Classes. Besides their common cliaracteristic, consciousness, mental facts have special characteristics which distin- guish them from one another and by which they may be divided into great classes. The necessity of this classi- fication is seen in the great multiplicity and variety of these facts. In the beginning of every science, the state- ment is necessary of the natural knowledge of resem- blances and differences, which we may use as a starting point for investigation. In this classification, two great dangers are to be avoided. First, many psychologists, neglecting real resemblances, have made too many divi- sions or faculties, in a measure dividing the mind into independent principalities and losing sight of the unity of nature which underlies all phenomena of mind.' Again, others go to the other extreme in excessive oppo- sition to the " faculty theory," especially in recent years, and fail to recognize essential differences in mental states.' In the main, however, it is agreed that there are three great classes of facts in the mental life, however strongly ' Reid, Stewart, Jouffroy. * Herbart, Ribot. The word faculty seems to carry a somewhat metaphysical meaning, as involving the cause rather than the simple class; properly restricted, it is synonymous -with, function. 35 36 CLASSIFICATION AND DIVISION tlie attempt to reduce tliem further may be urged. Tliese three classes express the result of three (Xi^imci functions of the mind : Intellect, Feeling, and Will. They may be called: 1st, Representative, or intellectual states; 2d, Affective, or states of feeling ; and 3d, Volitional, or states of will. These great departments of mental fact are shown in the very distinct propositions, "I feel some- how," "I know something," "I do something."' § 2. Justification of this Classification-. I. In Experience it is complete. The grounds of this classification are found in immediate consciousness, and it can find its justification only in an appeal to direct experience. The representative states have as their common characteristic their reference to a thing or ob- ject. Knowledge is a function of mind only as there is some thing to be known, and in the higher forms of its operation its states are taken to represent or signify objects. In its earliest beginnings also, in sensation, the objective bearing of knowledge, as affording us a reference away from ourselves to a something which is presented to consciousness, is its distinguishing feature. The affective states, on the contrary, as states of feel- ing, lack this element of objectivity and carry with them only reference to self : that is, they are states in which consciousness is itself affected primarily (pain, fear). They may be entirely lacking in the presentative or knowledge element, or the two may be combined in any degree of connection. They extend from the simplest bodily feelings to the highest emotions, and include im- pulses, temperaments, and personal tendencies of all kinds. ' Ward, Encyc. Britannica, art. Psychology. CLASSIFICATION: ITS JUSTIFICATION. 37 In strong contrast to these well-marked divisions the third class, volitional states, stand out in consciousness distinguished by a characteristic foreign to the other two, the sense of effort or exertion. It takes the forms of mental attention, choice, and resolution. The other orders of mental facts may or may not exhibit this will- element. I may be passively affected by pain or emo- tion, or I may be conscious of a free play of presenta- tions with no effort of my own to control or direct them. This last phase, therefore, may be set apart as a third class, and as representing a third function. It is held by some that all our conscious states and acts cannot be brought into these classes. Language is sometimes said to require a separate division. But it is difficult to see how the symbolism of language differs from tlie symbolism of the notion which it represents. The notion itself represents a generalization from other representative states. And the organic power of speech cannot be considered mental. The activity of cdnscience also is in dispute. It is held that con- science has both a cognitive (representative) and a motive (emotional and volitional) function. But as its representative activity is admitted to be in the presentation of relations of good and evil, its motive force is only that which attaches to all relations, except that it is the most powerful. Intellectual considerations of all kinds affect the will as motives, and it is as motives that considerations of right and wrong affect the will : these motives are most powerful because they are con- siderations of conduct, and conduct is the sphere of the will; but they are nevertheless considerations. So we may class conscience as far as its content is concerned in the represen- tative function of mind, and find in itself and its relation to will a reason for its volitional importance. Another point of confusion in regard to conscience arises from the fact that an appetence or primary instinct of our nature, also, is love for good and aversion to evil, this love and aversion being in the affective class. This adds, certainly, new and very greatly in- creased force to the motive or volitional value of moral dis- tinctions. If by conscience we understand the entire reason for conduct, then conscience is derived from the threefold activity of mind taken together; but if by it we mean the power by which we distinguish good and evil, it is represen- tative. 38 CLASSIFICATION AND DIVISION. II. This classification does not admit of further reduction.^ Besides the general consideration already spoken of, that the quality of representation is absent from feeling and will considered alone, we find the distinction strongly brought out in the independent vai'iatio'iis of which we are conscious in the case of each. The facts of intellect and of feeling, for example, are observable in diiferent degrees of connection with each other. States of con- sciousness seem sometimes to have no distinct feeling of pleasure or pain. And some states of pleasure and pain convey no knowledge. Our internal and organic sensa- tions, loud abrupt noises, give us no knowledge except the general location of our bodily organs, while the per- ception of a printed page may convey no positive feeling wdtli it. The demonstration of a geometrical truth may vary in its emotional quality from high pleasurable ex- citement to complete indifierence. All this shows that the two classes of facts can exist together; or that one may vary while the other does not, even to limits at which either element seems to disappear. It should be noted, however, that this mobility and changeableness is greatly in excess in the case of feeling. The rational principles of representation remain fixed in their characteristics, and vary only in the degree of vividness which they present. This fixity makes science possible. In every-day exjoerience our ideas become common property with a fixed meaning to diiferent minds. But affective states are not so. In the same individual, feelings and tastes change constantly. And in different men, these differences are exceedingly great. For example, in the matter of dress, form and color are kept within given limits, but within these limits there is every degree of individual taste. Different persons also have characteristic casts of character, as being intellect- 1 Cf. Rabler, loc. cit. pp. 83-87. CLASSIFICATION : ITS JUSTIFICATION, 39 ual or emotional ; the latter are movable and in constant change ; the former fixed in their purposes, methodical and regular in their life.' The opposition between representative and affective states is also shown in the influence they exert upon each other. On one hand, the affective states hinder and interrupt the order of intellectual states. Pleasure and pain when intense, forbid all continuous activity of mind. The habit of indulgence in pleasant states enervates the intellect. On the other hand, intellectual states seem to hinder the emotions. This is seen in the proverbial coldness of highly educated people. In the same soci- ety, the instructed and uninstructed classes are strongly contrasted in this respect. The ignorant classes are im- petuous in their emotions : they move in masses carried away by a common feeling, political or social : so much so that it has been said that the " excesses of political revolutions are in inverse ratio to the intellectual devel- opment of the people." ' The connection between these two classes of states and the will is perhaps more intimate, because every act of will involves both an idea of the end in view and a native impulse or appetence to its accomplishment. But it is still true that they can be clearly distinguished. A great number of thoughts and feelings in certain circum- stances have no bearing on our volitional life. They are matters of indifference to us. The reading of a historical narrative, for example, may be accompanied with great pleasure, and yet have no apparent effect upon my course of life. The developed forms of will are in conscious- ness quite distinct from the motives which lead to voli- tion. And as has been said of intellectual and emotional temperaments, so also men differ in their volitional cast. All these differences are traced back to the funda- ^ Paffe, Considerations sur la Sensibilite, p. 55. ^ Ibid., p. 103. 40 CLASSIFICATION AND DIVISION. mental one already pointed out, that in strong will there is the massing or concentrating of the mental nature in an effort accompanied with a feeling of the expenditure of force.' § 3. Unity of the Three Classes iisr Consciousness. With the distinction of the three classes of mental fact and the three functions they represent clearly brought out, it must still be remembered that the latter are merely functions. They are not three psychological lives which lie parallel with one another. They are a single life. Their unity in a single principle may be seen under several aspects. I. They have unity of end. The^y are functions of a common mental organism and minister to its develop- ment. The unity of the body is realized in the unity of the functions of the different organs. The end of all is the conservation and development of the whole. So the intellectual functions are one, in their tendency to pre- serve the independence of the self and accomplish its des- tiny. " By intelligence we conceive the end of conduct, by sensibility we are excited to produce it, and by will we govern these impulses in the light of reason and assure the victory of the best. Without intelligence, man is blind ; without feeling, he is inert ; without will, he is a Slave. II. They are one in their collective activity. Each seems to depend on the others in an essential way. At- tention is necessary to all thought, and feeling is often necessary to direct or is effectual in preventing the direc- tion of the attention. In its reflex activity', attention seems to be a representative or relating function, but it has the fundamental quality of will in its active exer- ' See Chap. V. * Kabier, loc. cit. Compare throughout this section. DIVISION OF THE SUBJECT. 41 cise as mental eflfort. A volition, as has been said, pro- ceeds upon ideas and appetences to such an extent that one school of psychologists reduce will to the conflict of ideas and another make it a conflict of feelings.' Feel- ing also involves images or ideas, through memory or imagination, or arises from association, and all of these are representative. And it seems possible, sometimes, to originate the train from which feeling arises by a powerful act of will. III. They find their formal unity in consciousness. The completed view of the mind ends, as it began, with consciousness, as the necessary background and formal unity of the whole. Consciousness besj^eaks the unit being, the subject of this threefold activity, and in its heathfulness or derangement, under normal stimulation of this threefold order, the proper balance and end of the whole is accomplished. § 4. Division of the Subject. In view of the above classification, the subject-mat- ter of psychology falls into convenient parts for treat- ment. In addition to the three great classes of facts spoken of, the form or mark which is common to them all, consciousness, must be considered. There are ac- cordingly the following four great divisions : Part I. General Characteristics of Mi7id. Part II. Intellect, Part III. Feeling. Part IV. Wm. ' Herbart and Bain respectively. 42 CLASSIFICATION AND DIVISION. On classification and division, consult : Porter, Human Intel- lect, pp. 40-51 ; Waitz, Lehrbuch der Fsychologie, ^ 4 ; (History) Drobisch, Psychologies §§ 123-138 ; Herbart, Lehrbuch der Psy- chologies pp. 38-90 ; Brentano, Psyfiliologie, I. pp. 233-306 ; Bailey, Letters on the Philosophy of the Human Mind, vi ; Jouffroy, Melanges Philosophiques, p. 312 ; Lotze, Microcosmus, II. ch. ii ,- Patton, Presbyterian Review, 1887, p. 771 ; Ward, Encyc. Britan- nica, art. Psychology ; Sully, Outlines of Psychology, ch. ii ; Rabier, Psychology, ch. viii ; Spencer, Psychology, II. ch. ii and ix. Further Problems for Study : History of classification in psychology ; Principles of logical classification. PART I. GENERAL CHARACTERISTICS OF MIND. CHAPTER IV. CONSCIOUSNESS. In the foregoing chapters the term consciousness has been used withovit explanation. Familiarity with it in the general significance it bears in ordinary discourse has been assumed. It is necessary, however, at the out- set, to inquire more fully into its nature and position in the science. § 1. Nature of Consciousness. Definition. Disregarding less important varieties, we may say that two general views of the nature of conscious- ness prevail among psychologists. On the one hand, it is held that consciousness is itself a capacity, function, or faculty of mind, an inner sense for the perception of the mind and its states, as sight and hearing are outer senses for the perception of body.' This view rests upon the fact of reflection, the developed means of observation of inner states, which has, in common with sense-perception, the relation of subject and object within itself ; but not upon the original awareness which we have of our first experiences. This latter bears no analogy whatever to external perception. Locke, who is looked to as the ' Reid, Stewart, Jouffroy. 43 44 CONSCIOUSNESS. great defender of the inner sense,' makes this distinction, since it is of attentive reflection that he speaks, distin- guishing it from simple consciousness. Ideas of reflec- tion are later than those of sensation, he says, " because, though they pass continually, yet like floating visions they make not deep impressions enough to leave in the mind clear, distinct, lasting ideas, till the understanding turns inward upon itself, reflects upon its own opera- tions, and makes them the objects of its own contempla- tion." This doctrine of consciousness as distinguished from reflection, makes it not essential, but accidental, to mind, an added thing, which may be wanting, as external senses, memory, imagination, may be wanting ; and ad- mits the supposition of unconscious mind. The opposing view is this, that consciousness is the common and necessary form of all mental states : with- out it mind is not and cannot be conceived.^ It is the point of di^dsion and differentiation between mind and not-mind. From the empirical point of view we may make the following observations : 1. Consciousness is not a potver or energy of mind. It does not involve the conscious eflbrt of attention. In a state of reminiscence, or revery, the states of mind are uncontrolled and come and go with no let or hindrance from the mind. We are then fully conscious of this play of states, but of no exercise of mental efi'ort accompany- ing it. 2. Consciousness is not an organ of the mind, to be used by the inner subject in perceiving his states. It is not an inner sense, since it accompanies the exercise of all the senses and is necessary to their function. The senses have specific physical basis also, while consciousness ' It " might properly enough be called internal sense." Essay, hk. 2, chap. I. sect. 4. 2 Aristotle, Mill, Hamilton, Ward. co:n'sciousness and the unconscious. 45 depends upou tlie healthy and normal activity of the sensorium as a whole. 3. Consciousness is the one condition and abiding char- acteristic of mental states. The possibility of the sejDara- tion of consciousness from mental states is held by many psychologists of the present day, and it is neces- sary to examine in some detail the grounds for the claim of the existence of unconscious mental pJienomena. § 2. COXSCIOUSNESS AND THE UNCOXSCIOUS. Meaning of the Term Unconscious. Unconscious men- tal phenomena play a great part in contemporary philos- ophy, and have since Leibnitz. It is necessary carefulW to distinguish the strict psychological meaning of the term from its philosoiDhical and metaphysical meanings, since it is only with the former that we have to do. We find attached to the word unconscious no less than three different significations. 1. By unconscious mind is often meant the hidden suhstratum of the soul which underlies all conscious manifestations, yet is never open to our inner gaze in its ov/n essential nature. It is held to be the unifying something beneath intellect, feeling, and will, the sub- stantial spirit. This is a metaphysical doctrine and does not concern us here, being one of the legitimate prob- lems of rational psychology.' 2. The word unconscious may again be applied to facts of least consciousness ; that is, to mental states which lapse from a state of conscious presentation into a region of such obscurity that they are practically lost to the conscious life. Such states may also arise from weak or habitual excitations, which do not ordinarily appeal to the attention.^ In this sense the reality of unconscious ' So Hartmann, Schopenhauer, and, in psychology, Maine deBiran. ' So Kant, Leibnitz, and the Scottish psychologists. 46 COWSCIOUSIiESS. states is undoubted, though some other term would better designate them, as distinguished from facts which have no mental reference whatever. However insensibly consciousness nia}^ shade away to its extreme limit, there must be a state in which it entirely disappears, and our phraseology should cover this distinction. Yet it is just here that the discussion before us may be said to turn ; upon the interpretation of states at one time below the threshold of the conscious life, but yet capable of emerging at any moment into clear conscious value. 3. Closely allied to the last position is the thorough- going psychological doctrine of unconscious mental mod- ifications. According to it, states which are at one time conscious may be at another time entirely uncon- scious, while still remaining mental. They preserve their mental nature, but lose consciousness. This doctrine may be kept strictly within psychological bounds ' or it may run into the metaphysical doctrine spoken of above.* Its psychological implications and truth alone concern us here. The arguments upon wliich it is based will be considered in turn. Arguments for the Unconscious: I. From the Principle of Causation. The argument oftenest used is based upon the law of causation, and takes a twofold form. a. It is argued that, if any cause produce a given effect, 'part of that cause must produce part af the same effect : hence, if certain ph^^sical excitations produce a mental effect, a diminished excitation of the same kind must also produce a mental effect. But diminished sense ex- citations produce no conscious effect, hence their mental effects must be unconscious. " I hear the noise of the sea," says Leibnitz, " but I do not hear the noise of each wave alone ; yet the noise of each wave must produce a mental effect, otherwise the whole together would pro- ' Lotze, Taine, Wuudt. ' Hartmann, Herbart. CONSCIOUSNESS AND THE UNCONSCIOUS. 47 duce no mental effect." " Suppose we take a wheel," says Taine, " with a hundred teeth, each tooth coming in contact with a bar as the whole revolves, and remove all the teeth except two, contiguous to each other. We will now have two shocks occupying .001 sec. and giving distinct appreciable sound. But if we take away an- other tooth the sound is no longer audible. Yet it must still be heard, for the conscious sensation produced by the two shocks was made up of the two elementary sensations." ' *' In the same way an optical sensation which lasts a second is made up of about 451 billions of unconscious sensations -^ because at the right of the solar spectrum where the vibrations of ether succeed each other most slowly, there are yet 451 billions per second." " Every minimum visihile,^' says Hamilton, " is made uj) of parts still smaller, which do not appear in consciousness, but have none the less produced a real modification in us." " When we look at a forest from a distance, we do not see the separate leaves or even the single trees ; but the green of the forest is made up of the green of the leaves, that is, the total impression of which we are con- scious is made up of an infinite number of small impres- sions of which we are not conscious." ^ Particular Answer. In the first place, we may say that, assuming the principle that part of a cause must produce part of the effect of that cause, it is contra- dicted by the conclusion in this case ; for if the whole effect is a fact of consciousness, the partial effect must be a fact of consciousness also. If a given cause pro- duces a sensation, and by this we mean a conscious sen- sation, we must understand it to mean conscious sensa- ' De I' Intelligence, 1st ed.. vol. i. p. 208, quoted by Rabier, loc. cit. p. 55 and fol. « Ibid., p. 237. 3 Cited by Mill, PJiilos. of Hamilton. 48 co:n'scious]S'ess. tion also when we draw the conclusion that part of the cause will produce part of the sensation. If the effect is not conscious, we can only say that it is not due to part of the same cause. So on this principle we can reach an infinite subsidence of sensation, but not the uncon- scious. h. The same principle is used in another way to prove unconscious states : if, we are told, the intensity of con- sciousness depends upon the intensity' or the degree of change'' of the phenomena it accompanies, then we would expect that when either the intensity of these phenomena or their degree of change is very slight, con- sciousness would be wanting altogether. Particular Ansiver. Again, admitting the principle of cause and effect, as stated above, this does not follow ; for if a certain intensity of the i^sychological phenome- non, say pain, produces consciousness and a part of the same cause produces a portion of the same effect, then any degree of pain, however slight, would produce a posi- tive degree of consciousness. If the external excitation as cause produces a given interna] fact as effect, then, on the same principle, this internal fact as cause should produce a conscious fact as effect, when it becomes in turn the excitation. General Ansiver. But further than this, the princi- ple upon which both these arguments rest is not true ; i.e., that part of a cause must have part of the effect of the whole cause. It is true that part of a cause must have some effect, but it cannot be said necessarily to have the same effect in kind as the cause of which it is a part. For the effect may be of such a kind that a cer- tain amount or intensity of the causal energy is neces- sary to produce it at all. If a certain velocity of wind is necessary to blow down the Tower of Pisa, can we say ' Beneke. * Bain. CONSCIOUSNESS AXB TEE UNCONSCIOUS. 49 that a wind of slight velocity blows it partly down ? Or if a certain force exerted in a blow on a percussion cap causes an explosion, does it follow that a lighter blow produces a slighter explosion? In these cases part of the cause produces no effect whatever of the specific kind in question. There is a minimum of cause necessary to the beginning of the efiect. Now the excitation of the nervous system is a cause of just this nature, considered with reference to mental effects. A certain strength of central stimulus is necessary to produce such an effect at all, and any action less than this produces no mental moditication. The real cause is the central process, and as Hartmiinn himself says, " a certain energy of cerebral excitation is necessary to provoke a mental reaction." The sound of a single wave, therefore, and the color of a single leaf, in the cases quoted, produce a physical ef- fect, but not a mental. Either they may not suffice to move the sense organ, or if they do, they may not suffice to stimulate the central process. This explanation holds also of cases in which the par- tial excitations are successive, as in the case of Savart's wheel, cited by Taine. By a property of the nerves, the successive stimuli overlap and strengthen one another, and so amount to a single intense excitation — as the waves of the sea and the leaves of the forest. The sounds of the successive teeth of the wheel do not reach consciousness in succession but simultaneously ; consequently, we can- not say that each has produced a portion of the effect. Let us sujjpose, for example, three sviccessive sounds, a, h, c, following each other at an interval of a thoiisandth of a second. The stimulus a reaching the auditory centre does not suffice to cause a conscious reaction, but its phy- siological effect persists more than two thousandths of a second; consequently when the stimulus & reaches the centre it reinforces a, doubling the central stimulus ; this again persists until reinforced further by the action of c, 50 CO^'^SCIOUSNESS. and tlie cerebral activity thus augmented suffices, for the first time, to cause a mental reaction.' The same case of accumulated stimulus is seen in the fact that when Savart's wheel revolves so slowly that the contact of a single tooth is audible, and then so swiftly that two teeth are heard as one, the latter sound is louder than the former/ And it is further supported by experiments in psychometry which show that when excitations follow one another in such quick succession that sufficient time is not given for the central nervous changes, difierent sensations are not distinguished in consciousness, but a single confused sensation is experienced due to the com- bined excitations. II. Argument from the Attention. Another class of arguments for the unconscious in the mental life, is drawn from the activity of attention. Excitations of sense, we are told, which seem to have no mental effect, may be made conscious simply by directing the atten- tion to them. The ticking of the clock is not noticed except when the attention is directed especially to it. The roar of the sea to the sailor, or the noise of his mill to the miller, are never heard under ordiuarj' circum- stances. Yet these sounds must have mental counter- parts, otherwise how could the attention serve to bring them forward? An experience often cited is that of walking : we are not conscious of our steps until we think upon the muscular and tactual sensations actually involved. And in general, close attention to any part of our bodies brings out innumerable slight sensations of which we were before absolutely unconscious. Ansioer. The best interpretation of these and simi- lar facts cited below seems to be gained by the study of attention itself. These facts certainly are true : whether 1 On such phenomena in sight, see Wundt, Phys. Psychologie, 2d ed., vol. I. p. 435 and fol. ^ Exner, in Pfi'tger's Archiv, vol. xi CONSCIOUSNESS AND TEE UNCONSCIOUS. 61 vre call them unconscious or conscious is only a matter of words. Tbey are of extreme value for psychology just for this reason, that they cast great light upon conscious- ness and its active form as attention.' There is certainly a region of such extreme indistinctness in the conscious field, that when the attention is concentrated in another portion of that field, the former region is quite beyond su- pervision. Whether it becomes merely physical change, as no doubt is the case in retention, or whether it retains some slight degree of consciousness, which is capable, as we see in the more active forms of mental function, of all degrees of intensity, is a question only of area for empirical psychology. We know that the withdrawing of attention does weaken the intensity of consciousness, and that this weakening is proportionate to the in- tensity of attention elsewhere ; so when the attention is fixed, concentrated, we would expect extremely slight degrees of consciousness in other portions of the field. Or the depletion of mind may be so great that the physi- cal process is no longer sufficient to excite a mental reac- tion at all. In this case it is a ph^'sical fact and not a mental fact, and is not of psychological value except as all physical processes are of value as conditioning the rise of mental phenomena. It is probable, therefore, that in such cases we have a condition of extremely diffused or weak consciousness. That we do hear the ticking of the clock, that the sailor is really conscious of the noise of the waves, and the miller of the sound of his mill, is proved by the fact that the cessation of these sounds is at once known. The child asleep in church wakes when the preacher stops. This shows that the preceding state of consciousness really included the prolonged excitation whose cessation is remarked, unless we hold with Bain that conscious- ' See Chap. V. 52 COJVSCIOUSNESS. ness itself is change. So also with the sensations of walking. However unconscious they may seem to be, we notice immediately any change in them, as when we step upon different material. The sensations which arise in a limb when it is strongly attended to, are probably excited by the attention itself, and are due to impulses, to movement, since the connection between attention and movement is so close that it is often impossible to sepa- rate them entirely. Sensations of blushing, for example, arise entirely from an inner feeling. These states do not seem to require, therefore, the doctrine of unconscious mind. The doctrine of " least consciousness " explains them sufficiently. III. Arguments drawn from Synthetic Sense-perceptionJ' The argument for the unconscious drawn from perception turns upon the co-ordination of sensations in the ideal pro- ducts, especially space and time. The intuition of per- cepts affords no basis for the doctrine, since the sensations upon which it proceeds are clearly conscious. We may take the visual perception of space, therefore, as affording the most plausible case. As we shall see in considering the perception of space,' the synthetic activity of mind, in the reconstruction of space, proceeds upon two classes of physiologica,l data. Both are presumed by this argu- ment to have a mental value since the resulting percept space is mental. But we are not conscious of these sen- sation or their co-ordination ; consequently' in them we have unconscious mental states. The resulting product is a conclusion or inference made unconsciously.^ Ansiver. In answer to this argument it may be said : a. That if this explanation of the perception of space be offered from an experiential point of ^dew, i.e., on the ground that these sensations are all that is re- ' See discussion of perception, Chap. VIII, especially § 4. ^Helmholtz, Zollner. co]S'scious:^Ess and the unconscious. 53 quired, through associative co-ordination, to account for the perception of space, then from the very fact that the process is unconscious, we may argue that this is not the true theory of the origin of the notion of space. Granted that there are these physical data to any degree, local signs conscious or unconscious, muscular movements of the eye, feelings of central innervation, yet it is diificult to see how these intensive states can by simple co-ordi- nation give extension. " Admitting differences in quality, we are asked to draw differences in position. A qualitative or quantitative difference in reds does not serve to locate one on the left and the other on the right." ' The notes of an orchestra, which form an intensive series, are not arranged in space. And it does not help matters to add any number of concomitant sensations, conscious or un- conscious, such as Lotze's slight sensations in the neigh- borhood of the point affected, and Wundt's " feelings of innervation." For if spacial co-ordination can arise from a second intensive series, it could as well arise from the first ; and if not, wherein does the hypothesis help us ? The advocates of the unconscious say, this process takes place, therefore there are unconscious mental states ; we may say, on the contrary, we are conscious of no such process, therefore it does not take place. b. Again, if we maintain that, while there are physi- cal stimuli which react mentally under the form of space and these data are the same sensational elements as those held by the empiricists in this connection, there is above this a native mental synthesis or reconstruction of these data ; we are still not shut up to the hypothesis of uncon- scious mind. For even though we admit that we are not conscious of these empii-ical elements, the law of ac- cumulated excitation already cited may serve us here. That is, physical data of a certain complexity and strength ' Rabier. 54 CONSCIOUSNESS. may be necessary to tlie mental reaction for si3ace, just as the physical stimulus for sight must have a certain com- plexity and strength. This requirement being unfulfilled, the stimulus remains physical and for that reason un- conscious. It does not enter the domain of mind at all. Yet, as a matter of fact, we cannot admit that the empiri- cal elements of sj)ace perception are quite unconscious. It is only by means of our conscious sensations that we have been able to determine these elements. Sensations, of movement are qualitatively conscious, apart entirely from their local character ; and, for all we know, sensa- tions arising from specific points in the skin and retina, called local signs, may have the same conscious value. To say that after the formation of the space notion these sensations do not stand out in consciousness alone, is. not at all to deny their essential conscious nature. The generalized concept arises also from individual empirical data, and the characteristics of the individual disaj^pear from consciousness in the product ; yet who would say that because the general notion tree does not bring into consciousness all the indi^ddual trees of our exj)erience, the original sensations of trees had been unconscious ? The difiiculty, of course, is to go behind the formation of the spacial j)ercept and see the data, as we can in the case of the general concept ; but until this is done, who can assert that these data are unconscious ? IV. Arguments draiunfrom the Phenomena of Memory.. A variety of empirical facts drawn from the varied as- pects of the representative function are urged in support of the hypothesis of unconscious mind, facts which find a complete explanation in the proper understanding of the physical process which underlies the revival of presentations. These facts may be classed under sev- eral heads. 1. Facts of Memory. It is urged that presentations are unconscious between their experience and their rep- CONSCIOUS]!^ESS AND THE UNCONSCIOUS. 55 resentation. "The larger part of our mental riches," says Hamilton, " is hidden away in the obscure recesses of the mind." These facts find complete explanation in the physical theory of retention.' The reproduced image is not the original presentation, but a new pro- duction, a re-creation, depending upon the re]3etition of the ph^'sical and mental conditions of the original presentation. Consequently, during the intervening time between the two experiences the mental state has simply not existed. 2. Facts of Association. It is often the case that an association between states of mind is accomplished with- out conscious links of connection ; consequently the links of connection must have been unconscious. Also that^ states are revived in consciousness of which we have had no conscious experience. Hence their first men- tal experience must have been unconscious. Further,* the brain must be the occasion of unconscious sensa- tions, whenever the activity is reinstated which has al- ready had a conscious accompaniment. Under all these forms of statement, and many others, the error already pointed out is plain. The assumption is made that a physical process of weakened intensity must produce a mental efi^ect, if the same process of heightened intensity produces a mental effect. On the contrary, we hold that the weakened physical process produces no mental effect whatever ; though it may serve, through its physical connections, to reinstate mental states. The missing links in broken chains of associations may be supplied from dynamic connections in the cerebral substance. The reproduction of the physical conditions of the last emerging image is suflicient to account for the revival of that image, by whatever means this physical reinstate- 1 See Chap. IX. '^ Lewes, Problems of Life and Mind, 3d series, p. 55. 3 Ibid., p. 165. 56 COJS'SCIOUSI^ESS. ment be brouglit about : whether by a cerebral process carrying consciousness with it, or not. Indeed, as Mr. Mill conjectured, the successive modifications of the physical series may occur so rapidly that sufficient time is not given for the regular appearance of the subjective series and some links are dropped out. This conjecture is sustained by a law of psychometry, that, in such cases, the physiological process occupies less time than the mental.' The production of new states, also, in old chains of association, is accounted for on the supposi- tion that, in the revival, the physical basis of the new states is sufficient for consciousness, while in the first experience it was not. And there is no necessity what- ever for Mr. Lewes' position that every subsequent rein- statement of a physical state once accompanied by con- sciousness must carry a sensation : it is only true when the reinstatement is strong enough to produce conscious- ness. 3. Facts of Habit. Further, habit is said to be a con- stant process of relegating to the unconscious acts which demanded at first conscious consideration and volition ; as piano-playing, reading. All such cases are accounted for by a further development of the physical basis of re- production. The simple fact that repetition of a given phj^sical performance tends to establish physical dispo- sitions which become automatic and mechanical,^ gives us at once a physical explanation of such habits. Voli- tion, instead of being unconscious, is entirely wanting. Why bring it in when the physical mechanism is sufii- cient for the required act ? The inherent contradiction in terms of the expression ''unconscious mental activity" is evident on its surface, and another name may be given to the large class of facts which it covers. Dr. Carpenter's " unconscious cerebration '' ^ is better, ' See p. 110. « Cf. Wuudt, loc. cit., 11. pp. 203-5. ' Humaii Physiology, Pbila. 1868, p. 589. COJS'SCIOUSJS'ESS AND THE UNCONSCIOUS. 57 if we understand cerebration to refer, not to the cerebrum sim- ply, but to the sensorium as a wliole. This empliasizes the physical nature of the process — which is really the only aspect under which we know anything about these facts. This whole field in its relation to cousciovisness lias been well called the sul-conscioio^, from the fact that images formerly in conscious- ness have now fallen below the threshold, but may again arise either when the stimulation of the centres is suflficient to draw attention or when the freeing of the attention from the point to which it was directed removes an impeding obstacle to the appearance of the image. Experiments by Fechner show that there is a point of lov/est consciousness for each of the senses: a least perceptible light, sound, etc. This is called the thresh- old value of the sensation. Let excitations of less strength be considered as uncojiscioiis or purely physical, all states ■which have appeared or may appear in consciousness as snh- conscious, and all states at present before the mind as cmi- Kciousj and for practical purposes this will serve to classify all the phenomena. A further beariug of the law already indicated — that the organism tends toward activities already performed — should be remarked. By this law the results of experience, mental as well as physical, are turned aside from the supervision of the mind and passed over to the body, in the sliape of refinements of nervous structure. The mind is freed from masses of de- tailed activities which become organic and reflex. What was once pure intelligence now becomes mechanism. This results in permanent modifications of structure which are handed down by heredity.' It is difficult to see the utility of the hypothesis of uncon- scious mental states in psychology. It may have metaphysical value in two very distinct ways: 1st, as "favoring a material theory of mind: for if the mental can ever be unconscious, why may not the unconscious be ultimately the ground of all the mental? And this is more clearly seen in the open view that such phenomena are distinctly organic although so closely in- terwoven with the mental. 2d. If all facts which form links in mental processes or produce mental products — as trains of unconscious cerebration ending in a conscious conclusion, or flights of musical or poetical genius — can be called uncon- scious cases of mental action, why may not the principle be extended to instinct, and design and adaptation in nature, and the conclusion of Hartmann follow? Mr. Lewes' argument for the unconscious is based upon ' Cf. Spencer, Psydiology, § 192. 58 CONSCIO U8NESS. a different conception of the matter of psychology. The essence of the mental to him is sentience,^ the capacity of tissue to react against external stimulus. Wherever, there- fore, we find sentient reaction, there is mind, whether it be conscious or not, and whether it be in the human cere- brum or in the leaf of the sensitive plant. All reflex and automatic action is mental. This emphasis laid upon sen- tience leads him to urge that the general condition of the sen- sorium or nervous system is often the determining factor of our mental states. This last inference seems to be true, and needs reiteration. The entire nervous system is a single organ of sensation, and its present state is a history of its life and the life of its progenitors. Generations of unconscious expe- rience are stored up in its present form. And unconsciously to us it gives tone and cast to our first impulses, directs the revival of images, and determines the effect of feelings. Conclusion. From the foregoing we conclude in har- mony with our definition of psychology, that conscious- ness is the " necessary condition and abiding character- istic of mind." Phenomena called "unconscious mental states" may be accounted for partly from the physical side, as excitations inadequate to a mental effect, and partly from the mental side, as states of least conscious- ness. Where, in the progressive subsidence of con- sciousness, these two classes of fact come together we have no means whatever of knowing. The phenomena are given their full psychological value, in the follow- ing pages, as we proceed. As Biuet says, if there be unconscious mental phenomena " we know absolutely nothing about them." ^ § 3. Kelative Theory of Consciousness. In the light of what precedes, a wide-spread but erroneous theory of consciousness may be examined ; the theory of the Bdativity of Conscioimiess. ' Lewes, loc. cit., III. chap. w\i. ^ Open Court, Jan. 34, '89. In addition to the references given in the course of the discussion and on p. 68 below, consult the articles by Pierre Janet in recent numbers of the Revue Philosophique. CONSCIOUSNESS AS A FEELING OF DIFFERENCE. 59 Considered in its strict bearing upon consciousness and not in its implications for the general theory of knowledge,' this doctrine takes a twofold form : first, consciousness is considered as a Feeling of Difference or Change, and second, it is considered as a Feeling of Re- lation betiveen Suhjex^t and Object. I. Consciousness as a Feeling of DifEerence.'^ Bain says^ "we are never conscious at all without experi- encing transition or change," " we know nothing in itself, we know only the difference that exists between it and something else," and " a change of impression is an in- dispensable condition of our being conscious, . . . every mental experience is necessarily twofold, ... in every feeling there are two contrasting states." ^ "Conscious- ness," says Spencer, " is the continuous differentiation of its constitutive states." While resting upon a large class of facts, this theory is not necessary for their explanation. It goes too far. It is undoubtedly true that change is a stimulus to con- sciousness. Stimuli long prolonged without change be- come less intense, and gradually so habitual that they are not observed ; but as has been already said, we cannot call them unconscious. Change in such conditions tends to revive the state and make it intense. The most that can be said is that change or difference varies the degree of consciousness, not that it constitutes it. If the latter were true we would never be conscious of a prolonged sense stimulus ; for however consciousness might be sustained in reference to other changing stimuli, it would not be sustained in reference to the particular stimulus which persists unchanged. But we are con- ' See Mill, Examination of Hamilton. ^ Bain, Spencer, George, W. Hagcn. 3 Senses and Intellect, 3d ed., p. 321. * Hid., p. 9. €0 CONSCIOUSNESS. scious of such jDrolonged states : the falling of the rain, the ticking of the clock, a fixed stare upon a motionless scene. Again, this theory confounds consciousness with its content, or that of which we are conscious. Granted that change is a law of consciousness, we ask : change of what? Of sensations. Then sensation existed before the change and sensations are conscious.' If it be re- plied that the sensations are unconscious, then we ask : how do you know that the}' are not physical ? And if it be replied again that consciousness is a function of j^hysical, cerebral, change, we ask again : how can con- sciousness be change when the change is not conscious ? As a matter of fact the examples cited in support of this theory are changes in consciousness, that is from one conscious state to another. If this be meant, then con- sciousness could never have begun except through dif- ferent simultaneous sensations. For example, we could not be conscious of the change in color from red to blue unless we already were conscious of red, except when the difference arose from their coexistence, an alterna- tive from which Mr. Bain, at least, is cut off. But even that alternative does not heljj the case, since granted a difference between two sensations, how do we reach a sensation of their difference ? — a question to be urged in speaking of the higher forms of consciousness. A real difference is not the same as a perceived difference.' We can conceive a consciousness in which real differences might not be perceived ; the destruction of memory would accomplish this for successive states. Therefore if we are not conscious of the states that differ, how can we arrive at a consciousness of their difference? The • Cf. Lotze, Logic, p. 20. - A distinction partially recognized by Mr. Spencer, Psychology, i. in>. ir,4-Fi. RELATIVE THEORY OF CONSCIOUSNESS. 61 feeling of difference is the content of consciousness, not consciousness itself. The facts on which this theory rests seem to be ex- plained by what has already been said about the uncon- scious. An excitation long persisting tends to become unconscious both from the withdrawal of attention, and the weakening of the central processes from exhaustion. It is difficult to keep the attention fixed steadily on one subject. It is soon drawn off, and as the mind becomes absorbed elsewhere, the former image falls into the subconscious. The organism, also, experiment readily shows, loses the elasticity of the first reaction, and its functioning is greatly enfeebled from the continued ex- penditure. A change in the conditions, however slight, draws the attention, at the same time brings new physical elements into play, and so stimulates conscious- ness. This is seen in the unconsciousness of ordinary sleep. It is produced by exhaustion of the body or by monotonous mental conditions which diffuse the atten- tion. But slight stimulations are sufficient to produce dreams or even to awake the individual, and it is possi- ble that a low state of consciousness persists during sleep.' In ordinary forms of hypnotism, the fixed mo- notony of impression produces semi-unconsciousness for the same reason. Even in lethargy where consciousness seems completely suspended, it returns at a single phy- sical excitation. If change at all be at the basis of con- sciousness, it is physical change ; but still it is absurd to say that this change is consciousness. 2. Consciousness as the Feeling of a Relation between Subject and Object. The second form which the general doctrine of the relativity of consciousness takes, is as follows : every state of consciousness is a felt relation between the presenting subject and the presented object. ' See observations by Radestock, Schlafund Trauni, pp. 102-108. '62 CONSCIOUSNESS. "Consciousness," says Mansel, "is possible only under the form of relation. There is no consciousness without the union of two factors ; and in this union, each is what it is only in virtue of its relation to the other." ' This form of the relational theory is likewise erro- neous. It overlooks the beginning of consciousness in child life and interprets only the contents of the adult mind. We have already seen, in speaking of method, that the early stages of consciousness differ from the later reflective stages in this respect, that there is a lack of the presentative or relational quality : a distinction which we find running through all conscious sensation. These states of pure subjective modification, having no reference to an object, such as simjjle feelings of pain, hunger, smell, are called affective as distinguished from jpresentative states."* Of these states, this theory ofi'ers us no explanation whatever. The earliest child conscious- ness is probably simply a mass of aftective states or a condition of general organic feeling, with no distinction between the me and the not-me. From this state the diiferentiatiug process of perception, by means of the presentative element of sensation, leads to the develop- ment of the consciousness of self and not-self.' But this theory also confuses the necessity of real relation, with the supposed necessity of a felt relation. In order to sensation at all there is of necessity' a subject and an object, and they must be related : but this relation does not enter into consciousness until the subject consciousness looks in upon itself, with its difi'er- entiating scrutiny. The distinction between early and late consciousness becomes emphatic in the lower ani- mals. The snail and oyster probably have no conscious- ness of self as different from not-self. From this simple ^ See Renouvier, Easais de Critique, I. cli. in ; also Spencer. 2 See Chap. VII, § 1. 3 See Chap. VIII. RELATIVE THEORY OF CONSCIOUSNESS. 63 state of feeling in the young child, the human self-con- sciousness is built up by known laws of mental growth. The two stages of consciousness may be called therefore respectively simple and reflective consciousness. The theory that consciousness is a relation is part and basis of the theory of the relativity of knowledge in general. If what we know in consciousness is a relation, what guarantee have we as to our knowledge of objects out of this relation ? The mental li-fe becomes the closed circuit of reality. But if, on the contrary, we see in consciousness, as the foregoing justifies, an individual knowledge of real states, that is, not a feeling of relation, but a simple presentation, be it thing or relation, it follows that every phenomenon of con- sciousness is a concrete reality, positive, original, single. ' It is just as we know it, and is, for us, absolute. The absolute is that which really is, and a sensation really is what it is felt to be. Nothing in the world could be more real, not the so- called things in themselves. Our psychic life is real and not a dream. The fact that in the developed or reflective consciousness the differentiation of subject and object is always present, that is, self-consciousness is distinguished from the consciousness proper of things, leads us to look upon consciousness as an in- dividual possession. My consciousness is my own and no one's else; and we know of no consciousness which includes all in- dividual consciousnesses. "Universal consciousness" does not exist as far as empirical psychology is concerned. If used at all, it means only what is common to individual consciousnesses. So reflective consciousness is the differentia of self , that which distinguishes me from all other thinking beings. It embraces simply the circumscribed area of my own experience considered in reference to myself. § 4. Aeea of Consciousness. The area of consciousness is the sum of the presen- tations at any time in consciousness, whether they be distinct or vague. Experiments show that twelve to fifteen strokes of a pendulum can be held in con- sciousness at once without counting or grouping. If they be grouped by fives, as many as forty may be re- ' Cf. McCosh, Cognitive Powers, pp. 21, 22. 64 CONSCIOUSJS'ESS. tained. The most favorable interval betweu tliem is .2 to .3 second.' Consciousness may be likened to the visual field in which objects are scattered, those being most clearly seen which are in the line of direct vision or centre of the field, and those which lie near the circumference most indistinct. Between these limits there are all degrees of distinctness. So ideas are distinct or vague in con- sciousness according as they are in the line of mental vision, or attention. The idea attended to is most dis- tinct, those connected closel}^ with it in any way less so, and those which are accidentally present and quite un- observed actively, least so. According as they lie in one or other locality of this general distribution, conscious- ness of them is said to have different degrees or forms . Degrees or 'Forms of Consciousness. These may be illustrated by an example. As I write, the noise of my pen is quite unnoticed. By the laAv of change, already spoken of, it tends to become indistinct. If continued some time, it is no longer heard and is said to be suhcon- scious. If, however, I am sufi'ering Avitli headache and noises irritate me, the scratch of the pen becomes pain- fully noticeable. The same is the case if the pen is a poor one and scratches more as used. But absorbed in my thought, I continue to write though conscious of the disturbing noise. It is then said to be in a state of passive consciousness. Thus a thousand things around us, the table, chair, books, are present to our minds, but we are passive in regard to them. If now I am led to direct my attention to the noise of my pen and to exam- ine the point in order to remedy it, there is an active putting forth of mental energy — a conscious expenditure of inner force. This is active consciousness or attention, and the process by which the attention is concentrated upon the image is apperception. ' Dietze, Phil. Siudien, in. p. 884. Cf. Ladd, loc. cit. p. 494. APPERCEPTION. 65" It is well to note the play of ideas tlirougli all these forms of transition, from the dark region of subcon- sciousness, to the brilliant focus of attention. Images pass both ways constantly, acting varyingly upon one another and making up the wonderful kaleidoscope of the inner life. Apperception. Apperception is the highest and most comprehensive form of active consciousness. By it is meant that activity of synthesis hy which mental data of any kind (sensations, percepts, concepts) are constructed into higher forms of relation and the perception of things which are related becomes the perception of the relcdion of things. " The two presentations a and 6," says Lotze,' " constitute simply occasions vv^hereby the reaction of a spiritual ac- tivity is aroused, through which new presentations, such as similarity, identity, contrast, arise, presentations which, would not be possible without the exercise of this new spiritual activity." The relation of percepts is not the same as the perception of relation. Apperception is the comprehensive " power of discovering relations" (McCosh) ; but is not limited to the operations of thought. It is the essential mental act, as shall appear, in the three great stages of mental generalization, j^ercep- tion, conception, and judgment." The use of the word apperception in recent psychological- treatises to express the broadest act of mental relation, is of great importance and value. The treatment of the very dis- tinct and familiar act of mind in attention, of grasping de- tails, detached and meaningless, and relating them to one another in a new mental product, has heretofore been con- fined to its special operations, as perception, conception^ judgment, to each of whicli a different name was given. The plirase apperception singles out that act of mind which is common to them all — the relating activity of attention — and • Outline of Psychology , § 23. ^ Cf. Martineau, Siudy of Religion, p. 194, and Laurie's distinction between attuition and intuition; Metaphysica nova et vetusta. 66 CONSCIOUSWESS. thus, by its general application, emphasizes the nnity of the intellectual function as a whole. In general, we may say, whenever by an act of attention mental data are tmified into a related whole, this is an act of apperception. ' § 5. Development of Consciousness. The beginnings of consciousness are enveloped in great obscurity. Shortly after birth a child begins to show signs of memory and of the power of connecting impres- sions. But both the memory and power of association are very weak and depend ujiou intense degrees of ex- citation, as a very bright light or a very loud noise. When the child is several months old, a familiar person is forgotten after a week's absence. Gradually attention is discovered, at first vague and discontinuous, and after a few weeks, voluntary.'^ This is shown earliest for sight and touch, the two senses which discover space rela- tions. It is probable that the earliest consciousness is a mass of touch and muscular sensations experienced in part before birth, and that it is only as the special senses become adapted to their living environment and sensi- tive to their peculiar forms of excitation, that the general organic condition is broken up and the kinds of sensa- tion differentiated. The power of visualizing or forming permanent images in memory for sight is developed from the fifth to the seventh year.' This process of differen- tiation of the sensations of touch and the muscular sense gives us very early the form of our own body, and the lo- calit}- of its parts, and this serves as point of departure for the placing of external objects. The movement of the body contributes largely to the apprehension of the dimensions, forms, and areas of things in space. The movements of the body are at first random and without ' On apperception, in general, see Wundt, loc. cit. p. 219. - Perez, First Three Years of Childhood, p. 25. ^ Cf. Jastrow, Princeton Review, Jan. '88, art. Dreams of the Blind. DEVELOPMENT OF CONSCIOUSNESS. 67 coutrol, arising from nervous discharge under conditions of physical discomfort. They gradually take on a pur- posive character, but even after two or three 3'ears it is difficult for the child to execute any given combina- tion of movements. This fact of control of the body seems to be the first beginning of the exercise of will. It involves a subjective reference more distinct and pecu- liar to itself than any of the purely affective sensations, and leads to the notion of the / and so to 5e?/'-conscious- ness. The development of consciousness is largely dependent upon the development of the physical organism. The senses must Ijo awake to their functions before the mind can exhibit its functions. Not till the eyes are open and in proper move- ment can the impressions of that sense begin to play their very great role in the forms of external perception.' So also must the centres become accustomed to their reactions. If we liken the elective activities of the developed nervous sys- tem to lines of least resistance, we may say that, for the very young child, such organic pathways are entirely wanting and they must be established and maintained by actual exercise. These early physical modifications becoming more and more definite and multiplied, the more complex forms of mental function are made possible. Like other organs of the body, also, the brain grows in size and complexity. It attains its largest developnunit. in size at about the end of the seventh year ; but its structural development, which consists in tlie differentiation of parts for special functions and the estab- lishment of various connections throughout its bulk, is then hardly begun. The basal ganglia seem to develop their ac- tivities earlier than the cerebral hemispheres. This is to be expected, since they are connected with the organic and es- sential processes of the body. On consciousness, consult: iu general, McCosh. Cognitive Powers., bk. 1, ch. H; Hamilton, Metaphysics, Lect. IX, XI-XIII, and XV; Fortlage, System d. Psychol., §§ 6-13 and 93-94, also Beitrcif/e znr Psychologic, ^ 15; Drobisch, Psychologie, ^§ 55-57 and § 29; Waitz, Lehrhiick cl. Psychol., §j 57-58; Volkmunn, Lehrbuch d. Psychologie, ^ 105-116; Ladd, Physiolog. Psychol., p. 585; Porter, Human In- tellect, pp. 83-119; George, Lehrhuch d. Psychol., pp. 222-234; Brentano, Psychologie, bk. 2, ch. n-iv; Wundt, Physiolog. Psychol., ' See Chap. VIII. 68 COIfSCIOUSJS'ESS ell. XV; Mansel, Metaphysics, pp. 33-66 and 183; Lotze, Microcos- 7nus, bk. 2, ch. i ; Rabier, Psychologie, chap, vi and vii ; Bain, /Senses and Intellect, pp. 325-339 ; (area of) Paulhau, in Revue Sci- entiflque, May 28, '87. On consciousness and the unconscious : Carpenter, Mental Phys- iol., chap. XIII ; Bventano, Psychol., bk. 2, chap, ii (of especial value); Lewes, Problejns, 3d series, pp. 143-196; Fortlage, Beitrdge zur Psychol., p. 164; Porter, Human Intellect, § 87; Hamilton, Metaphysics, Lect. XVIII; Ardigo, liivista di filosofia scientifica, Jan. '88; Colsenet, La vie inconscient de V esprit; Janet, Revue philosophique, xxii. p. 577; Sergi, Psychologie Physiologique, bk. 3, chap, i; Mill, Examination of Hamilton, chap, viii-ix, also chap. XV; Hartmann, Philosophy of the Unconscious, 0; Lipps, Orund- thatsachen des Seelenlebens, p. 125; Kadestock, Schlaf und Traum, pp. 284-287. Furtlier Problems for Study : Eise of consciousness; Animal consciousness; Theories of consciousness; Higher forms of consciousness. CHAPTER Y. ATTENTION. § 1. Definition" of Attention. In the consideration of consciousness, a difference "was found in its general aspect according as a number of presentations were loosely scattered about its field or as some one held the mind directed to itself. Con- sciousness is thus passive or active. Active consciousness is in general attention. It is the act of holding a pres- entation before the mind. It is in all cases a conscious act. What goes on in the relating of this presentation to others, in their combination, dissolution, arrangement, is due to the activity of apperception, which is, in a large measure, mechanical and subconscious : but the at- tention which makes the activity of apperception possible is known at once. Attention as Mental Energy. The most essential pe- culiarity of attention is the feeling of expenditure which its exercise occasions in the mental life. Mental ex- haustion and fatigue invariably follow a more or less prolonged stretch of the attention. Mental states may play for an indefinite period in consciousness without impairing our mental freshness and vigor, provided the attention is not directed to them. Further, it may be said, indulgence in air-castles, day-dreaming, and ram- bling meditation, is a means of recovering intellectual freshness after a strong effort of attentive thought. This results from the diffusing of the attention over a very wide field and relaxing control of the flow of ideas. 69 70 ATTENTION. This fact in its bearings upon the mental life, as they shall appear in the course of our exposition, leads us to see in attention the only exhibition of mental energy as distinguished from mental states : and in the conscious- ness of this abiding energy we find the ground of men- tal unity and personality: Keflex or Involuntary Attention. Upon observation of ourselves we find that attention may be stimulated either from some foreign and unexpected source or from the will. A loud noise, a violent contact, a disagreeable odor, at once attract the attention without our volition or even against it. This is reflex or involuntary attention. In the normal state of the consciousness, attention is con- stantly open to appeals of this kind. Minds with little power of will live under control of such external excita- tion. The attention is drawn hither and thither in rapid transition with no fixed concentration upon any sen- sation or idea. In such minds, as we shall see later, the functions of apperception are disturbed, and its prod- ucts unstable. This state of inability to hold the atten- tion against other solicitations is called distraction : the attention is, as it were, drawn apart in its efibrts at adaptation to different conditions. Another form of involuntary attention is found in cases of insistent ideas.' It very frequently occurs in normal life that a single idea, either by reason of a strong association or of a feeling, or because of previous attention, or even in consequence of the very efi'ort of the will to banish it from consciousness, remains before the mind and holds the attention. This is called an in- sistent or, in its more intense forms, Jixed idea. It is generally removed by a change of scene, companions, 1 Called in German Zwangvorstellung : from Kraff t-Ebing. See art. on Attention by Ribot, Revue Philosophique, Feb. '88. Cf. George, Lekrbuch d. Psychologic, p. 374 and f ol. VOLUNTARY ATTENTION. 71 and surroundiugs, the old association being broken or new ideas claiming the attention. As an idea becomes fixed or imperative, it gathers round it other ideas in growing associations and connections, which soon give a morbid tone to the entire mental life. This is the be- ginning frequently of monomanias and permanent delu- sions,' which become chronic in insanity. Frequently also, it is supposed, the primary tendency to some form of nerve disturbance or brain disease, due to heredity, gives occasion and strength to such derangement. The mechanical nature of involuntary attention and its intimate relation to all physical and mental states is seen in the acts of a patient in a state of hypnotic hallu- cination. Here it seems that the element of will is en- tirely eliminated. The patient has absolutely no con- trol over either body or mind, and any suggestion either phj'sical or mental from the hypnotizer is immediately realized in action. It seems only necessary that the at- tention should be secured, to start the entire train of apperceptive processes with the physical changes which are associated with them : or a physical attitude or movement may be forced upon the patient, only to be followed by all the emotional and intellectual states it suggests. In these states, the intellectual life seems quite normal and the emotions are very excitable and facile in their play ; but all inner control is lost. Action results with complete necessity. The important fact in this form of hypnotism then seems to be the fixing of an idea till it becomes imperative, with the general subjec- tive state unchanged by the substitution of ideas which, it brings about. Voluntary Attention. In strong opposition to this is voluntary attention or attention proper. It may be de- fined as a state, of active consciousness due to voluntary ^ See case described by Cowles, Amer. Jour, of Psych., Feb. '88. 72 ATTENTION. mental exertion or effort. Here a distinctly new element enters into consciousness, mental effort. In voluntary attention we find the first exhibition of will. It is the beginning of all control over the mental life. A thou- sand things may appeal to me for consideration and I may refuse them my attention. I may give mj^self to a train of thought and be substantially unconscious of sounds, sights, contacts which would ordinarily excite my attention. It is thus in the familiar condition of ah- straction or absent-mindedness. This peculiar outgoing of the self is the something we call consent, in the mental life. From it we first arrive at consciousness of self, by a reference of what we do, to ourselves as doing it. It makes possible, as will appear later, the fixing and con- nection of ideas in the higher forms of thought. The frequent or prolonged exercise of attention to the same presentation or idea tends to bring it involuntarily before the mind. Its repetition in varied circumstances establishes various associations by which it may be re- vived. Insistent and fixed ideas usually become so from voluntary thought upon them — from what we call " brooding " over a subject. Thus the line between re- flex and voluntary attention is changed and much that was before a matter of choice becomes automatic and necessary. § 2. Beakings of ATTEXTioisr iisr the Mental Life. In its relation to the great classes of mental facts, the attention is of the first importance. In general it may be said that attention intensifies a mental state. It may be considered more particularly and in detail. I. Relation of Attention to Sensation. There is a two- fold or reactive relation between attention and sensation. On the one hand, increased intensity of sensation draivs the attention. The change in intensity of the sensation is RELATION OF ATTENTION TO MOVEMENT. 73 a direct stimulus to the attention, by forcing its appear- ance in consciousness : and the attention in this case is reflex. On the other hand, attention directed to a sensa- tion increases its intensity. We have already seen that many sensations may lie in consciousness almost unfelt, while tlie attention is otherwise occupied. It is only necessary to direct the attention to them to give them their full force. But more than this, the attention may give them increased and very acute intensity. By fixing the attention upon bruises and burns, we increase the pain they give us. Hence the efforts we make to divert a sick man's attention from the seat of his disease, by fixing his attention on some new artificial sensation, or by interesting him in another topic of conversation. Hot cloths relieve headache, by producing a counter- irritation. This effect of the attention is especially great in nervous diseases. Paralysis has been cured or driven from limb to limb in hypnotic patients by a mere sug- gestion, which so completely occupied the attention as to induce belief in the effect. So insomnia and some- times dyspepsia and other diseases may be cured.' Attention has an influence also upon the time occu- pied by a sensation. Experiments show that a certain time is necessary for the feeling of an excitation from any of the sense organs and the reaction in the move- ment of the organ. This time is greatly reduced when the excitation is expected.^ A certain time seems to be necessary for the adjustment of the attention to the nature and source of the stimulus, and this is reduced when the idea is present beforehand and the attention is already partially adjusted. II. Relation of Attention to Movement. The move- ment of the members of the body is very closely connect- ' See Albert, Beitrag zur therapeutischen VerwertJning des Hypnotis- mus, and Amer. Jour, of Psychol., II. 2, sect, on Hypnotism. - For details, see section on Fnychometry (Chap. VII, § 6). 74 ATTENTION. ed with corresponding ideas. No voluntary movement takes place without its idea in the mind : and often tha idea produces the movement without any voluntary im- pulse or even contrary to it.' The imitative faculty of children shows this tendency to carry out all movements thought of. We often find ourselves following the movements of the hands or lips of a speaker with slight movements of our own. It is probable that no word comes into the mind without its partial formation by the vocal chords, as is seen in the movements of the lips by many in reading to themselves and in our thinking aloud. No doubt the physical association involved plays a great role in all such cases. The thought of a movement has preceded and led to the movement so often, that there is a positive tendency, at the nervous centres, to the discharge of the energy necessary to the accomplishment of the act, along the proper courses. The act of will, then, seems to be selective and directive of this energy of nervous discharge. This tendency to movement is greatly increased by the exercise of attention. The attention tends to bring^ the idea more distinctly before the mind and thus re- moves all competing ideas Avhich should incite to differ- ent movements. This is especially the case when the attention dwells upon the organ or on the thought of movement. There is then a twofold effect due to the attention. It tends to develop latent sensations, as we saw above, in the organ, and these sensations lead to movement for their relief or continuance ; or it produces movement by the distinct purpose to perform an act thought of. For example, if the picture is vividly pre- sented of a workman who has his thumb crushed by a hammer, we make instinctive movements to protect the thumbs, by folding them in the hands. ' Fere claims that every sensory excitation at first induces an aug- meutation of motive force which is measurable on the dynamometer. RELATION OF ATTENTION TO THE INTELLECT. 75 The facts of hypnotic suggestion already spoken of show the automatic connection between an idea strongly attended to and its physical performance. The absence of will does not destroy the power to perform the action, but only the power to prevent or direct it. The con- sciousness is so contracted in this state that each idea in turn is held in the focus of attention.' III. Relation of Attention to the Intellect. Attention, either voluntary or reflex, is directly involved in the operations of the intellectual functions. It is the merit of the French philosophers of the spiritualistic school to have brought out the fact that volition enters in the most primitive forms of intellectual synthesis.* In gen- eral, it may be said that attention increases the vividness of representative states and thus renders more definite and lasting the apperceptive activities of synthesis, analysis, relation, as seen in memory, association, judg- ment, and reasoning. It is necessary, first, to the reten- tion of images. The capacity to retain mental pictures depends upon tiie intensity' of the original presentation, and the clearness of its relations ; and this intensity and clearness are enhanced by the attention. The supply of materials which we have for use in the higher forms of thought depends at once upon our attentiveness to what passes before us in our every-day life. When we wish to retain any event, we press it upon the attention and note its surroundings. Second, attention increases the intensity of the reproduced image in the same way. If we recall the face of a friend, it is, at first, dim and indis- tinct, but by holding it closely before us and scrutiniz- ing it, we can bring it clearly out in more detail. The attention shifts rapidly from point to point upon the ' On the motor accompaniments of attention, and its affective bases, see Ribot, PsycJiologie de l' Attention. 2 Cf. Part IV, on the Will. 76 ATTENTION. image. Tliird, tlie duration or time of all mental states, as of simple sensation, is made shorter by attention, as is seen in experiments on the association of ideas and esti- mation of differences.' In the view of some, the higher processes of the intel- lect, depending as they do upon the active principle of atten- tion, are forms of the activity of attention.^ So Prof. Wundt in his doctrine of ajiperception as a relating activity, which is at once a form of will. It cannot be doubted that it is only in and through attention that mental synthesis and elabora- tion take place, yet it seems truer to the facts to separate voluntary attention from this process. Apperception can then be used for the generic activities of synthesis and rela- tion, which take place through either reflex or voluntary attention. Wimdt fails to discriminate sufficiently between reflex and voluntary attention in his doctrine of ajjperception.^ IV. Relation of Attention to Feeling.'* Attention has the same intensifying influence upon the affective states in general as upon sensation. Emotion is heightened when the attention is directed to it. Hope, joy, fear, anger, grow very greatly in intensity when thought of, and as quickly die down when dismissed from the atten- tion. With the higher emotions it is very difficult to control the attention, so thoroughly do they usurp the field of consciousness. So, also, pleasure and pain, called the tone of feeling, are increased by being attended to and diminished when the attention is withdrawn. The especial relation existing between the attention and the feeling of interest has often been remarked by psychologists. This feeling of interest is often akin to that of personal advantage or indi\'idual preference, ■which we find playing an important part in the flow of our associated ideas. It gives a spontaneousness and 1 See Cbap. VII, § 6. « See Lotze, Metaph., % 273. 3 Cf. Volkmann, Psych., pp. 191-2. * Attention as a form of will is treated under Will. TRAINING OF THE ATTENTION. 77 ease to the attention which renders the latter more affec- tive and less wearisome to the inner life. Attention to that which interests us does not demand the outgo of mental effort. V. Relation of Attention to the Bodily Functions. Attention long directed tends to derange the automatic functions of the body. The automatic functions are those which go on unconsciously to ourselves. The action of the heart is accelerated by being closely at- tended to. The digestive apparatus may be deranged by being watched, and so also m&j the breathing pro- cess. Attention is also accompanied by certain attitudes of the bod}', such as turning the ear or eye in a given direction, bending forward, frowning, and other muscular contractions. A feeling of tension also is felt in the end organ. This tends to show that it is the motor elements of the brain which are involved in attention, while the effect it works upon the sensation shows a sensory modi- fication following upon the other.' § 3. Educational Bearings of the Doctrine of Attention." Training of the Attention. The considerations al- ready advanced tend to show the importance of the attention in education. The secret of the case rests upon making attention completely voluntary. Strength of thought depends very largely upon the voluntary con- trol or concentration of attention, in such a way as to pre- vent distraction from accidental and unexpected influ- ences. This training of the attention should begin at the earliest possible period. The child should be taught to observe continuously some thing that interests him, ' Cf. Ladd, Phys. Psycliology, pp. 538 and 542, and l^\xndA,Ibid., ii. p, 210. 2Cf, Sully, Outlines of Psychology, p. 103. 78 ATTENTION. and encouraged to ask questions about objects and their relations. In very early life these things should be left to his own selection, until the laws of apperceptive syn- thesis are develoj^ed, that is, until he learns somewhat to connect things and events and see their bearings. Otherwise the forcing of the will may interfere with the development of the emotions, which are then the control- ling factor. But as soon as practicable, the teacher should attract and hold the child's attention, at first to pleasant things and afterward to indifferent things. Great care should be exercised in the general surroundings. All distractions, such as open windows, pet animals, play- things, should be guarded against : they practically call upon the child to attend to several things at once. Care should be taken also not to fatigue the attention. The periods of study had better be too short than too long ; for if the child grows tired, the effort becomes painful and the subject distasteful. Frequent recesses should be given and recitations should not be longer than fif- teen to twenty minutes, for children under twelve to four- teen years of age. The child's interest should never be allowed to flag. Habits of Attention. In this way regular habits of attention may be formed very early, which have the same force in life as all other habits. Attention thus becomes application, which is voluntary and agreeable : and with this basis the student has no trouble in devot- ing himself to subjects of thought for longer periods. A caution is perhaps in order, as to sameness in the kinds of instruction given in early life. It is well that the same general cast of thought should not engage too much of the early attention of the student. It gives a bent to all his subsequent development. John Stuart Mill is a good example of this. It is especially danger- ous when it involves the emotional side of our nature. HABITS OF ATTENTION. 79 Religious teachers use this fact not only properly to instruct in morality and religion, but also to excite early prejudices and repulsions which can never be shaken off. Nurses often give children associations of fear which persist through life. This is the origin, frequently, of the insistent ideas spoken of, which intrude themselves upon us and make many of us to a degree hobbyists and monomaniacs. On the attention, consult : "Wundt, Physiologische Psychologic, II. p. 205 ; Carpenter, Mental Physiology, ch. iii ; George, Psychol- ogie, pp. 84 and 538-543 ; Waitz, Lehrbuch d. Psychologie, § 55 ; Hickok, Mental Science, pp. 66-72; Fortlage, System d. Psychologie, p. 100 and §§ 46-47 ; Ribot, Psychologie deV Attention ; Ohev&iemQV, Brain, I. p. 439 ; Cappie, Brain, ix. p. 196 ; Sully, Outlines of Psychology, ch. iv ; Dewey, Psychology, ch. iv. § 5 and his references, pp. 154-5 ; Ladd, Pliys. Psychology, pp. 538-42 ; Stewart, Philos- ophy of the Human Mind, pt. 1, ch. ii ; Lewes, Problems of Life and Mind, 3d series, p. 184 ; Bradley, Mind, July, 1886. On apperception : Waitz, Brundlegung d. Psych. , p. 77 ; Wundt, loc. cit. ch. XVI, and LogiTi, I. pt. 1, ch. ii ; Erdmann, Vierteljahr- schriftfilr wissenschaftliche Philosophic, x. p. 320 ; Lange, Philoso- phisclic Studien, iv. 3 ; Dewey, Psychology, pp. 85-90 ; Ribot, 6*^?'- 7nan Psychology, p. 220 ; Lotze, Metaphysic, bk. 3, ch. m ; Staude, Philosophische Studien, i. p. 149 ; Volkmann, Lehrbuch d. Psycho- logie, f§ 110-114. Further Probletns for Study : Physical accompaniments of attention ; Affective or emotional basis of attention ; Accommodation of the attention to its object ; Relation of voluntary attention to will. PART II. INTELLECT, CHAPTER VI. DIVISION OF THE INTELLECTUAL FUNCTIONS. The Intellect is the faculty of knowledge. It includes tlie following functions : I. The Apperceptive Function, which in turn com- prises : 1. Presentation or Acquisition, being a. Sensation ; h. Perception. 2. Representation, being a. Conservation or Memory ; h. Combination ; c. Elaboration. II. The Rational Function. §1. DeMARKATION of the FUITCTIONS. I. The Apperceptive Function. Under this function are included all those operations which take place under the activity of apperception ; those which owe their jDro- duct to an active spiritual synthesis.* The function of Presentation or Acquisition is that by which the material of knowledge is gained. It covers ' See the definition of apperception, Chap. IV, § 4, 80 DIVISION OF THE FUNCTIONS. 81 the tAvo sources of our knowledge in experience, Sense- perception and Self -consciousness. The function of Representation, as the word implies, is that by which the material acquired in Presentation is retained, reproduced, and intelligentl}^ used in the pro- cesses of mind. Its operations are considered under three great heads : a. Conservation or Memory, which in- cludes the Retention, Reproduction, Recognition, and Local- ization in time, of Representations ; h. Combination, which is the disposition of these reproduced states in the new forms of the Imagination, the law of its disposition being Association ; c. Elaboration, which is the function of intellect projoer, constituting the operations of ThougJit. Under it we find again three mental stages. Conception, Judgment, Reasoning. The Elaborative function is further distinguished from the other apperceptive functions as being discur- sive, rather than sensitive. The sensitive operations are more closely connected with the known conditions of the bodily organism and are common to man and the ani- mals. The Elaborative and Rational functions, on the contrary, show a free development of mind away from the data of sense and thus seem to distinguish man from animals. II. The Rational Function. All the foregoing opera- tions, both presentative and representative, are subject to a law of universal validity, the law of Identity or Non- contradiction. And the intelligence when exercised upon things in general is governed by the principle of Suffi- cient Reason. As judgments these principles are also apperceptive, but they are not contingent upon experi- ence, as other judgments are. These with other prin- ciples of the same nature, as causation, right and wrong, run through all knowledge and constitute the Reason. THE APPERCEPTIVE FUNCTION. PRESENTATION. CHAPTEK YII. SENSATION. § 1. General Nature of SEiyrsATio]sr. Sensations are the primary events of tlie mental life. They are so called because they arise through the senses. We use the word in its usual sense, as meaning the great body of psychological phenomena, both affective and presentative, which result within the mind immediately from impressions upon the senses. The presentations of moisture and resistance which follow from contact with a piece of iron, and the pain felt in case it is hot, are equally sensations. Tliere are several meanings given to the word sensation, two of which are strongly upheld in opposition to the meaning given above. Sometimes it is applied to phenomena purely phAfsical, that is, phenomena without consciousness. Claude Bernard and Lewes speak of the sensibility of living tissue, meaning to express the fact that living tissue has tlie property of contracting under excitation. Mr. Lewes' says tliat ''reflex action is a sentient process," and Gerdy° defines sensation as "the change that takes place in the organ affected under the influence of an excitation." But the use of the words sensa- tion and sensibility in this sense is quite iinwarraiited. L^sage requires the limitation of these words to the facts of conscious- ' P)'ob. II, 3d series, chap. viii. ' Les Sens et I' Intelligence. 83 I BISTUWTION BETWEEN SENSATION AND IMPRESSION. 83 ness. To apply them to facts of tlie physical order, to desig- nate by them a property of unconscious matter, is to enlarge the domain of psychology, with Lewes, until it loses all charac- teristic limits and becomes a department of biology. For such phenomena the words impression, contraction, contractility, may be used, but not the word sensation. But even with this limitation, another meaning is often given to sensation; it is used to designate jyleasure and jt>«{?i, as they follow the excitation of the sense-organs. In this case the Avord perception, which is contrasted with it, is used to signify the qualitative element, as sound, color, which results from the impression. In this sense, sensation is exclusively an affective and never a presentative phenomenon. The dis- tinction is a true one, in fact, and is always to be made ; but we cannot use the word sensation to designate pleasure and pain alone. We shall find another term, as used in current discussion, to cover this distinction.' From whatever standpoint we approach the subject, it is universally confessed that experience gives us the first ele- ments of knowledge. Sensations are the beginning of experi- ence, and it is by sensation that we must begin the study of the intelligence. Distinction between Sensation and Impression. Sensa- tion being thus defined, it must be carefully distinguished from the physical phenomenon which precedes or accom- panies it. The impression is the modification of the organ, especially of the nerves and nervous centres, which arises from an external stimulus ; as the vibration of ether or air. The nature of the different sense impres- sions is not well understood ; but in each case they are some form of movement. They liave all the charac- teristics of physical phenomena : tliey can be localized, measured, apprehended b}' the senses. Sensation, on the other hand, both affective and presentative, cannot be compared wdtli movement of any kind. The differ- ence between them is plainly seen in the fact that an im- pression may take place without any sensation. The impression may be too feeble, or too prolonged, or too ' For the different meanings of the word sensation, see Hamilton s Beid, Note D. 84 SENSATIOm often repeated, as tlie irritatiou of our clotliing, to w]iiclx we are habituated : or the attention may be occupied, so that the impression does not produce its usual sensation. Affective and Presentative Elements in Sensation. In most sensations there is a distinct knowledge element over and above the intensive subjective state, which con- stitutes the sensation proper. There is an element of knowledge of things without us or of our own bodies. This is the presentative or perception element in sensa- tion. It is often called "original perception" in distinc- tion from the " acquired " ' or, as we shall say, synthetic perception of objects in their completeness in space. There are great differences in sensations in this respect. And it seems proper to divide the senses into three classes, according as the presentative element is prominent or not." First the sensations of the inner organs of the body, called organic sensations, and of passive touch and temperature ; then sensations of taste and smell ; and finally sensations of hearing, sight, and active touch. In the first class the affective element j)redominates and seems to constitute the whole sensation. In the transi- tion to the second class, and finally to the third, this element disappears by degrees, while the presentative element increases. In the organic sensations, we have no appreciable knowledge, but in sight and hearing we may have much knowledge and very little feeling. Ham- ilton announced the law, already anticipated by Kant,' that the two elements vary in inverse ratio — which is true in a very rough way." The question as to where perception begins in distinction from sensation is very difficult. It seems to be true that in ' See McCosh, Psychology, vol. i. p. 28. ' J. Lacbelier, Cours inedit. 3 Antlmqwlogie, p. 139. ■» Metaphysics, vol. ii. xxiv. I CHARACTERS OF SENSATION: QUALITY. 85 most sensations tliere is an immediate perception of a not-self, to which the sensation is referred, as opposed to self. ' Under this aspect we call the phenomenon perception; while consid- ered as a modification or experience of the self alone, it is sensation. It is really the same fact looked at in two ways, M. Rabier's limitation of the affective element to pleasure and pain cannot be upheld; since a sound may be purely affective Avhether pleasurable or painful or neither, as a loud unlocal- ized and unrecognized sound. Pleasure and pain are purely affective, but they are not the whole of the affective quality of sensation. The relation of the two elements in the different senses will be spoken of under the various kinds of sensation respectively. § 3. Chakactees of Seksation. All sensations have certain general characters, whicli are subjected to investigation. These characters are four in number. I. Quality : that property by which sensations are distinguished as coming from different senses, such as color, sound, taste. II. Quantity : meaning intensity or mass of sensation. Investigations in intensity constitute Psychophysics.' III. Duration: the time occupied by the sensitive function with its accompanying physical and volitional processes. Investigations in this field constitute Psy- choinetry."^ IV. Tone: the pleasure or pain which accompanies all sensation. These characters are considered in order. § 3. Quality of Sensatioist. There is much uncertaint}^ as to the proper classifica- tion of the sensations. It appears very easy to discover at once what is immediately given as a pure and simple sensation. But it is not so. At the age of maturity, when one is able to make an analytical study of his sen- ' Hamilton, Metaphysics, vol. I. p. 193. ^ See table-p. 31. 86 SENSATION. sitive states, lie finds tliem no longer in tliat pure and primitive state which he would wish. They have under- gone a twofold alteration. In the first place, all our senses act together, and different sensations, by virtue of the laws of association, are integrated as one. And further, by virtue of the same laws, intellectual ele- ments are superposed upon our sensations, making them much more complex. These associations become, after time has made them habitual, almost indissoluble. So that it is very difiicult to isolate the different sensations from one another, or the great body of sensitive data from the contributions of reason and experience. Hence ob- servation is not sufficient. As we have already seen, recourse must be had to experiment for the production of artificial conditions ; and to abnormal cases, such as when one of the senses is wanting from heredity, disease, or accident. Smell. The complication of data spoken of may be illustrated in the sense of smell. The pure sensation cannot be isolated : it involves both intellectual data and a multitude of other sensations. Among the acquired notions which a given odor involves, is the representa- tion of the object from which the odor proceeds, an association extremely serviceable to man and animals in finding and testing food ; the more or less exact notion of the direction and distance of the object ; and finally the idea of the organ of the body which is afl^ected. The local- ization of smell in the nostrils is very vague and gives us little knowledge. On the other hand the concomitant sensations with which this sense is connected are very numerous and complicated. First, there are organic and vital sensations arising from the digestive and respiratory tracts. We distinguish between appetitive odors and nauseating odors. The odor of meat excites the appe- tite of carnivorous animals, and that of a full pantrj SMELL: TASTE. 87 moves our own. And in relation to respiration, odors are fresh, as that of Cologne-water, which excites a feeling of freedom in breathing ; or suffocating, as that of a long-shut-up house, which seems to hinder respiration. Second, we find sensations of taste always associated with those of smell. The organs of taste and smell seem to act in sympathy. "We speak of delicious odors as giving us a taste of the object beforehand. Third, sen- sations of touch are associated with smell in the mucous lining of the nostril, as in impressions which involve a tickling sensation. Fourth, there are also muscular sen- sations arising from the movement of the nostrils in breathing in odorous vapors. Fifth, to these we add sensations of temperature, heat and cold. The odor of camphor seems cold and that of alcohol warm. It has been found impossible to isolate pure sensa- tions of smell for classification or description. The most we can do is to throw them into general classes, as aromatic, fragrant, pungent, which a.re not at all exhaust- ive. This applies in a measure also to the other sensa- tions, though in a less degree in the higher senses, sight, touch, and sound. Taste. Taste is involved in the same obscurity. We only know that it has its organ in elements on the sur- face of the tongue, called gustatory bulbs or flasks, which communicate with the sensorium by the lingual and glossal nerves. The intimate connection with smell is seen in the fact that the impairment of smell by disease or cold injures the power of taste. Tastes are infinite in their variety and cannot be classified. Certain classes of tastes are well discriminated in experience, such as sweet, bitter, sour ; but they are very few compared with the vast number which remain undescribed. The pre- sentative element in sensations of taste is very slight. We have an indefinite feeling of the locality of the sensa- 88 SENSATION. tion, but this arises, in the main, from feelings of touch upon foreign substances in the mouth, and from the muscular movement of the organs inyolved in eating or drinking. No knowledge of the object affecting us is given immediately in either taste or smell, since the stimulating agent is in gaseous or soluble form. Organic or Systemic Sensations. There are through- out the body various organic sensations which are quite internal and only indefinitely localized. Such are the visceral sensations, respiratory sensations, feelings of bodily comfort or discomfort in general. Their most marked characteristic is their tone value, the high de- gree of pleasure or pain which they contain. These sensations, however vague and general, are of great im- portance to the mental life. They are the background of our emotional condition — since they indicate an ele- vated or depressed condition of bodily vitalit}^ — and give general cast to our state of mind. The dyspeptic soon becomes unreasonable and gloomy, and biliousness in- terferes with the normal activity of the mind. The gen- eral condition of the sensorium as a whole is often a determining factor in thought and conduct. It is notice- able that changes in climate and weather have a great influence upon these organic feelings, largely through the elevation or depression of the respiratory function. Muscular Sense. The earliest of the senses in its de- velopment is the muscular sense. By it is meant feelings of the activity of the muscles of the body as concerned in movement. As to the existence of such a class of sensa- tions, as seen in lifting, pushing, straining, and in the weari- ness that follows muscular exertion, there is no doubt. Many psychologists, however, attempt to resolve them into sensations of touch,' or consider them as an "assem- ' So Rabier, PsycJwlogie, pp. 103-108. MUSCULAR SENSE. 89 blage of sensations of different categories." ' The former, liowever, cannot be held, since such sensations remain after complete destruction of the sensibility of the skin and in cases of anaesthesia of the limbs. Beaunis finds that a singer retains control over the vocal chords, after their sensitiveness to touch has been destroyed by co- caine." Clinical cases show the same for the limbs. This indicates that the skin is not the organ of muscular sen- sations unless' motor habit be so established that the skin is no longer necessary, though at first involved. But, further than this, the muscular sensations have charac- teristics peculiar to themselves. There are two distinct elements involved in voluntary movements of the mus- cles: first, db feeling of effort, and second, a, feeling of resist- ance. The feeling of effort arises from the expenditure of nervous energy at the centres, and is called &\^o feeling of innervation. The feeling of resistance, on the other hand, seems to have its seat in the muscle affected. It is the sense of opposition to muscular movement, and is connected with sensations of pressure spoken of later on. Both of these seem to be involved in muscular sensa- tions, though either may be present without the other. In cases of paralysis and muscular anaesthesia, there is the feeling of effort with no corresponding muscular movement ; and, on the other hand, if the hand or arm be contracted by galvanism, in contact with a solid body, we have the feeling of resistance or pressure without that of effort." The feeling of effort accompanies the exercise of will in the adult consciousness ; but in child life it arises as soon as the limbs are moved and ' Ferrier aud James. For theories of the physical basis and classi- fication of these sensations, see Wundt, Theorie der Sinneswahrnelimxmg, p. 376. '' Mind, July, 1887, p. 430. ^ Lewes. * So Bernhardt; of. Ladd, Phys. Psyeh., p. 345. 90 SENSATION. encounter resistance, and tlie idea of self as active prob- ably conies tbrough tbis feeling. Around it tlie begin- nings of attention arise. Feelings of resistance also arise equally early in child experience and are exceed- ingly important as giving the first knowledge of the ex- ternal world.' We are conscious of opposing force, and thus arrive at the first condition of matter. It is well to repeat that it is through muscular sensations, with the attention and will which they involve, that we have the idea both of mental and of physical force. As to the mechanism of the nuiscular sense, great obscurity envelops the whole subject. Three distinct theories of tlie nervous accompaniment of these sensations are held, each by eminent authorities in physiology and psychology. It is held by some that the feelings of muscular activity arise from the pulling and crushing which the muscles occasion in the neigh- boring parts — the skin, joints, ligaments, tendons — and that they are transmitted to the brain by the ordinary sensor courses. This may be true, even in the face of the fact '' that muscular movement is unimpaired when the posterior or sensor roots of the spinal cord are cut ; since the control of muscular move- ment can be shown, in frogs, to be independent of muscular feeling. The difficulty with tliis view is that the ordinary sensor nerve endings, being largely external, do not seem suffi- ciently distributed to report muscular activity. The feeling of muscular pain and weariness also persists after all activity and seems to issue from the body of the muscle itself. Con- sequently, it is held by many,^ that there are distinct sensor nerve fibrils in the muscles, which are either continuous and parallel with the motor courses, or are branches of the main sensory nerves." This theory is probably true, but it accounts, however, only for the feeling of resistance — actual sensations in the muscles, — not for the feeling of effort. The latter may be entirely absent. Hence a third general view," that ' On the iraportance of feelings of resistance, see Spencer, Psycltol- ogy, II. ch. x\ai. '■' Brown-Scqiiard. 3 E. H. Weber, Sachs. * For evidence, see G. S. Hall, Mind, iii, The Muscular Perception of Space. 5 Bain, Wuudt. MUSCULAR SENSE. 91 the muscular sensations are essentially feelings of movement and have their seat entirely in the motor apparatus. The sense of effort is due to the voluntary liberation of motor energy upon the courses: it is entirely central. The degrees of feel- ing of movement vary with the inner estimate of this expen- diture or innervation. This explains the feeling of effort and is the only explanation of it, but it takes no account of the distinctive muscular sensations which result from movement. These Bain admits arise from the "sensitive filaments."' It is therefore probable, on the whole, that the feeling of effort or cause arises from central motor innervation, and the feeling of resistance or effect, from a sensor apparatus, either ordinary or special. This is supported by the close automatic connection between sensation and motion in general. The clear distinc- tion between the two classes of sensations is seen in a case reported by Demeaux" of a woman who had lost all muscular sensibility, both deep and superficial, and while the power of voluntary movement remained, was yet ignorant of the actual movement, and the position of the limbs. The sense of effort remained, but the sense of resistance was gone. It is largely due to 3Iaine de Biran, the eminent French philosopher, that the feelings of effort and resistance, as under- lying the idea, of will and force, are prominent in psychology. He held that in the fundamental act of effort accompanied by resistance, there are immediately given self and not-self, the will and the external world. This is seen to be true as a growth in child life. Prof. Bain calls it the most "vital dis- tinction within the sphere of mind." Hence M. Rabier's crit- icism of Maine de Biran ^ is mistaken. He analyzes the feel- ing of effort into will and external resistance, and says both are presupposed, forgetting that this analysis is made after the feeling is complete, and that neither knowledge of will nor of body is present or possible before the union which gives the feeling of effort. Presentative Element in Muscular Sensations. Com- bined with touch, the muscular sense affords us knowl- edge of extension and space. Sensations of contact, as shall be seen below, repeated on successive portions of the skin or by the same portion on different parts of the object, present data for the projection of a fiat surface. ' Senses and Intellect, p. 77 ; also see quotation from Ludwig, p. 79. 2 Brain, Mar. '87, p. 11. ^ Psycliologie, pp. 104 and 105. 92 SENSATION. It is bj pressure adclecl to these sensations that we come to apprehend depth. It is sufficient to remark tliis here, reserving its further discussion for the section on the perception of space.' Mr. Spencer, speaking of the sen- sation of resistance as involving feelings of eft'ort, says : *' This sensation is at the bottom of our concejition of the material universe, for extension is (as apprehended) only a combination of resistances ; movement is the generali- zation of a certain order of resistances ; and resistance is also the substance of force." * Taken alone the muscular sensations give us little knowledge. We know from them the location and move- ments of larger or smaller masses of the body: but even this knowledge is very vague, since without touch and sight these movements cannot be coordinated, nor their amounts estimated. Hearing. Sensations of sound have a specific quality which is known through the ear.' The psychological value of these sensations consists in the fact that they occur purely in time and have no spacial quality. A series of sounds is the type of pure temporal succession. Presentative Elements in Sensations of Soiind. The three most presentative classes of sensations, we have said above, are those of sound, sight, and touch. In the case of sounds, we find peculiar properties upon which exact methods of research may be brought to bear. These properties, therefore, are presentative, in that they can be construed by the intelligence. Like other sensations, sounds may be distinguished in intensity in an exact wa}^'' This intensity depends upon the amplitude 1 Ch.VIII, §4. ^ Loc.eit. 2 For the mecbanism of hearing, see Bernstein, Five Senses of Man. «See§5. HEARING. 93 of tlie vibrations of the sonorous body. Further, they are distinguished iu their timbre, which depends upon the addition to the vibrations, which produce the funda- mental tone, of other vibrations twice, three times, . . . as rapid. This difference in timbre gives its charac- teristic sound to different materials, as metallic, vege- table, and thus corresponds to the difference in kind of odors and tastes. But the special peculiarity of sounds in this particular is found in what is called tone as dis- tinguished from noise. This quality of the tone or note is tonality or height, depends upon regular periodical vibrations, and varies with their number. There is nothing corresponding to this iu smell or taste. We cannot make up a scale or gamut of tastes as we can of notes. Upon this peculiarity of sound, having its basis of sensation probably in the fibres of Corti in the coch- lea of the ear, or in the fibres of the basilar membrane to which they are attached, the whole science of music is built up.' There is probably, in the inner ear, a series of vibrating elements which correspond, though more minutely, to the intervals of the musical scale. The perception of distance and direction by the ear is largely acquired by association." Sensations of sound are singularly free from the dis- turbing influence of other sensations, and for this reason they are directly accessible to experimental researches of all kinds. We shall find this the case in speaking of the other characters of sensation. Sight.3 Sight is perhaps the most presentative sense. It gives us direct knowledge of the external ' See Cournot, Du Fondement de nos Connaissances, i. p. 215. * On the function of the semicircular canals as giving balance in space, see Chap. VIII, § 4. * For the mechanism and general facts of sight, see Bernstein, loc. cit., and Le Conte, Sight. 94 SENSATION. world. Its affective qualities consist in tlie pure inten- sity of tlie light sensation — as the light of one candle or two — and in the distinct order of sensations known as color. The sensations of color arise from the rapid- ity of vibration of particles of luminous ether. These different rapidities give an ascending scale through the seven colors of the rainbow, from the red to the violet, similar to the scale in sound sensations, though not as extended or exact. The colors shade off into one another with no regular law of change. Sensations of color have intensity, saturation, and tonality. The in- tensity, says Helmholtz, depends upon the quantity of light. Saturation is the relative j)urity of a color. De- grees of saturation are known as shades, as pink in its relation to scarlet. Tonality is the quality of the color as determined by its position in the scale of the spec- trum, as blue, green, yellow. The spacial form of the objects of sight is one of the most interesting of its presentative properties. This will be discussed in the treatment of s]3ace form.' The fact that there are two eyes contributes to this result, especially in the perception of the third dimension. It is difficult to isolate pure sensations of sight from the muscular and tactual sensations which are always, in actual life, associated with them, and it is probable, as will appear later, that these — especially the muscular sensations — are also concerned in the formation of the notion of space. In regard to the process of the perce^Dtion of color through the eye, two principal theories have been advanced, assuming that the retina is distinctively the locus of this process. We find, in the retina, distinctly differentiated and minute nervous elements called rods and cones which, it is thought, react locally, thus making possible the picture of the object seen. But as to the color sense proper, the case is more uncertain. Accord- ing to the Young-Helmholtz theory, there are three different ' Chap. VIII, § 4. SIGHT. 95 kinds of nerve fibre, each of which reacts to one of the three fundamental colors, red, green, and violet: the other colors are complex and result from their combined action. Tliis theory is very generally accepted. Among other objections to it, it is urged that the microscope reveals no such differen- tiation of fibre, and the smallest sensation which can be per- ceived by the eye is of white light, which involves all these ele- ments.' The other theory is that of E. Hering, who supposes that there are two kinds of elements each capable of two dif- ferent reactions, thus giving four fundamental colors, red, ^reen, blue, and yellow. This theory, however, has also grave difficulties to face." Yellow can be produced by the combi- nation of red, green, and violet. The phenomena of color-blindness support the general view of the differentiation of structure or function in the nerve elements of the retina. This is the inability of about one person in twenty to distinguish certain colors. Blindness for red is most common. It is thought tliat all cases can be reduced to blindness either for red or green ; though there are cases in which only different degrees of gray are distinguished. To the latter, all objects seen are like the photographs of the same objects. Different regions of the retina have differ- ent degrees of sensibility to color; this sensibility growing less as we go outward from the central part. The outer rim of the retina is normally insensitive for red, but reacts for the other colors. This shows that there are special fibres which react only to red.' A further phenomenon, that of after-images, is especially noticeable and important in sight. After-images are the per- sistence of sensations after their peculiar stimuli have ceased to act. Look at a bright window and then close tlie eyes, and the after-image is seen. This is called a positive after-image, and is due to the dying out of the nervous process. If the bright object be colored, its after-image plays between that color and its complementary (the color needed to make white in composition with it). This is due to the exhaustion of the nervous elements involved in the original color, by wliich white light is broken up and only the complementary elements act. This persistence of sensation in the organism is important as explaining compound and intensive forms of excitation. As ' Fick. ^ On these theories see Le Conte, SicjM, and Wundt, PTiys. Psych., 2d ed., I. p. 460; and in criticism of Hering, see Kries, Arch. Anat, andPhys., 1887, p. 113. 2 On color-blindness, see Fick, Zur Theorie der Farbenhlindheit. 96 SENSATION. Fechuer has pointed out, the after-image has onl}^ two dimen- sions and thus differs both from the actual percept and its re- vived image. Touch. Sensations of touch constitute the base of a variety of sensations which we distinguish ordinarily as qualitatively different. We have seen that an element of touch enters in sensations of muscular movement, both from external contact and from the rubbing of the inner parts against one another. Besides, we distinguish sen- sations of the rough, smooth, coarse, polished, damp and sticky ; but physiologists have shown that they are not s]3ecial sensations, as Beid believed, but acquired judgments based upon modifications of touch, combined with the feeling of resistance already spoken of. The importance of touch, as being capable of so man}^ modi- fications, as having its end organs over all parts of the body, and as acting in conjunction with other sensations in their peculiar organs, is seen to be very great. The presentative quality of touch, considered quite alone, is space, as it is built uj) from the recognition of the locality of the parts of our own body.' The nerve elements of touch or pressure are clearly de- fined. They are corpuscles situated in the skin, which com- municate directly with the great sensor nerves by I'amifying fibrils. These corpuscles are distributed in varying number in different parts of the skin. The experiments of E. H. Weber showing this are celebrated. He employed dividers opened at varying degrees, the minimum distance felt between the points being the diameter of the smallest "sensation- circle." The tip of the tongue and the red of the lips have great delicacy of touch ; while the back of the neck is very insensible. The circles, however, are not the smallest units of tactual sensation and must contain many nerve elements; for it has been shown that there are distinct and very minute pressure spots within these circles." The same is seen in the marvellous capacity of this sense to become more delicate with • See Chap. VIII, § 3, n. ^ Goldschneider. TOUCH: TEMPERATURE SENSE. ' 97 exercise. In the hypnotic state, also, delicacy of discrimina- tion by touch is greatly exaggerated/ From the universal presence of touch and its immediate reference to the external world, it is of great importance in cases of appeal from the other senses, and in cases of lialluci- nation. When in doubt about the objects of vision or sound, Ave feel after them with the hand. For this reason, touch is called the '^controlling" sense. Temperature Sense. The last of the senses, in order of mention as in order of discovery, is the temperature sense. Like touch, it is a universal sense and has its end apparatus in the skin. Minute points called " tem- perature spots " which react, some for heat and others for cold, are scattered over the skin in varying degrees of nearness to one another. They have been j^lotted on the backs and palms of the hands and on the arms. Of the ditierent nerve terminations in the skin — elements of Krause, Paccini, and Meissner — it is impossible to tell which belong to touch and which to temperature. The varying number of these spots in different localities and the consequent variations in delicacy of perception of heat and cold, make quantitative measurements for this sense very difficult. These sensations have a \erj slight presentative element in their vague reference to bodily iocalit}'.'' From this general survey of sensation, in respect to quality, the distinction between affective and presenta- tive elements in sensations is more clear. In each sense, when the affective element is strong the presen- tative is faint. When a very bright light strikes the eye, it produces a strong affective sensation, but vision is indistinct. On the contrary, when we read printed words, they represent thought, but are only slightly af- fective. The case is the same with sound and touch. > Binet and Fere, Animal Magnetism, p. 135. '^On the temperature sense, see Donaldson, in Mind, No. XXXIX. 98 SENSATION. § 4. Proof of the Specific Nature of Sensations as RESPECTS Quality.' The sjDecific diflerences in sensations are denied bj a school of psychologists, who hold that the seven orders of facts found here can be reduced to a single principle of sensibility. This tendency to unity is the dominating characteristic of modern science and finds as bold, if not as successful, an application here as in the external sci- ences. Theory of "Unity of Composition " of Mind. In the reduction of mental phenomena to unity, three stages of the process ma}' be distinguished. The first stej) is that of the sensationists, who reduce all mental facts to sen- sations. Ail the facts of consciousness, intellectual, af- fective and volitional, are transformed sensations. The second stage consists in the reduction of ail sensations of a given class, as color, to a single generic sensation of that class, as, for example, a single color, which serves as basis for the derivation of all the colors. And the third stage is reached when all these generic sensations are reduced to a single form for all classes, a truly primitive form of consciousness. This, while having no deter- mined and definable quality of its own, yet produces by composition with itself, first, the generic sensations, then the different species or kinds under these general quali- tative divisions, and then the whole mental life in its liigher forms. First, the mental life is reduced to sen- sation, then to generic sensations, and finally to one ele- mentary sensation. It is the second and third of these steps which concern us here. The arguments in favor of this hypothesis of unity are of three kinds : first, analogies based upon the mate- ' The development of this paragraph follows substantially Rabier, loc. cit. chap. xi. THEORY OF UNITY OF COMPOSITION OF MIND. 99 rial sciences ; second, inductions drawn from tlie analy- sis of psychological phenomena themselves ; and third, the argument from the fact that this hypothesis succeeds in explaining many perplexities in psychology. I. Analogies: a. deduction of the Physical Forces to Unity. Two arguments based upon the ph^-sical sci- ences seem at first sight to render the hypothesis of unity probable. All the physical forces are being resolved into move- ment, although in ajopearauce nothing could be more difterent than sound, light, and heat. In experience we find nothing in common between the sound of a bell and the color of flowers, between the heat of the sun and the fall of a stone. And in the old physics, each of these was looked upon as a different principle. But the great discovery of the transformation of forces has taught us that these different forces are in reality one and the same, and that all their phenomena represent but a sin- gle fact, movement. If this is so, we have by analogy a strong presumption that the corresponding psychological phenomena may be reduced to unity also.' Beply^ The force of this analogy is based upon a misconception of the true meaning of the law of conser- vation of energy, or transformation of force. It is not true that force is transformed at all, it is only true that there are no distinct forces to be transformed, that our old conception of separate forces was mistaken. So there is no reduction of things which are different to unity. It is only shown that one cause, motion, underlies many specifically different manifestations, or takes on many specifically difierent forms or degrees. And as far as this is concerned, we may admit the same of the different sensations, referring them to a general principle of sensi- bility which takes on specifically difierent forms. This is ' See Mantegazza, Transformation desfwces psychiques, Rev. Philoso- pliiquc, !Mar. '78. 100 sensation: wliat is meant when we say that all sensations are affect- ive states ; that in them all, our subjective sensibility is aroused. But this does not in the least degree affect the fact that, as mental states, as data of the inner life, the sensations of the different senses are specifically different. This parallel, tlius understood, is further emphasized by the fact that recent work in neurology shows all nervous en- ergy to be essentially the same, and further to be a form of motion. The nerve courses are functionally indifferent : any nerve stretch might serve for any sense, and the motor nerves substituted for the sensor and vice versa. It is prob- able that the end organs impart to the courses distinct forms of motion, which are due to the form of the stimulus in each case, and that these forms are interpreted in their specific sensations through the reaction of the general sensibility.' h. Chemical composition of simple substances in a compound of unique proj^erties, affords a second anal- ogy. It may be stated in the words of Mr. Spencer. "Multitudinous substances," says he," "that seem to be homogeneous and simple prove to be really het- erogeneous and compound, and many that seem to be unrelated are shown by analysis to be near akin. . . . Moreover, there is reason to suspect that the so-called simple substances are themselves compound, and that there is but one ultimate form of matter out of which the successively more complex forms of matter are built lip. . . . (From this) we conceive the possibility that the multitudinous forms of mind known as different feelings may be composed of simpler units of feeling and even of units fundamentally of one kind." ^ Reply. This analogy is subject to the same criticism as the foregoing. It does not distinguish actual things in nature from our mental pictures of these things. In ' This parallel is used to prove that mental force is also a form of motion, but without sufficient ground. ■■' Princ. of Psychology, vol. i. pp. 155 and 156. ^ See a similar argument in Leibnitz, Nouveaux Essais, vol. ii. eh. i, §15. THEORY OF UNITY OF COMPOSITION OF MIND. 101 order to make the analogy liold, we would have to con- sider presentations as substantial things with properties of their own, capable of uniting and dividing by their own force. They would have to be entities with difler- ent properties, like ox^-gen and hydrogen. But this is not at all the case. Mental facts are simple states and they are nothing independently of the mind whose states they are. They are the expression of the activity of mind which is one and the same in its different opera- tion. So any conception according to which these states unite by their own inherent force and form a complex is definitively ruled out. If there be a complex of these simple forms, as we shall see there is, it must itself be due, as they are, to an activity of mind ; it must be also a function, not a thing or substance, and must owe its properties to the mind and not to simpler mental states. Further than this, it may be said tliat this analogy rests upon a false interpretation of the fact of chemical composi- tion. It is not true in fact that the union of oxygen and hydrogen gives a substance whose properties differ absolutely from those of the constituents. It is an apparent sensible difference, not an absolute one. The difference between the liquid water and the gases which compose it is only a differ- ence in the position of the atoms and in the extent and direc- tion of their movements. In tlie molecule of sulphuric acid, which is composed of one atom of sulphur and three of oxy- gen, there is, to use the figure of Ampere, a small planetary system, in Avhicli these atoms are arranged in a definite order and move with a definite rhythm.' Now in this combination, the atoms have not lost their properties, nor lias the whole taken on any new properties. So the difference between the compound and its constituents is not a real difference in the things as things. But the difference between the sensations as sensations is a real difference. As soon as we attempt to re- ' Wundt says : " There e.xists in the molecule a certain equilibrium of oscillating movements whose interruption at any point destroys the whole until the equilibrium be again established." — Phys. Psychologie, :2d ed., ii. 463. C£. Clerk Maxwell, Rev. Sckntifique, xii. p. 367, - Spencer, ihid. Cf . on Cornposition of Mind, Taine, loc. cit. 102 SENSATION. duce these differences, we go beyond the range of sensation altogether. II. Arguments Draion from Psychological Analysis. The attempt is also made to base the theory of the unity of composition of mind upon psychological analysis. Are there any cases of the transformation of psychic force, or of mental synthesis ? If so, this seems to afford a solid basis for the hypothesis. It is admitted at the outset that observation gives us no facts of this kind \ but it is held that by different physical and physiologi- cal experiments sensations have been decomposed. The results of such exj^eriments have been formulated in two great laws, which, if true, are as important for the science of mind as Kepler's laws for the science of the heavens. 1st. A sensation which is simple and undecomposable in. consciousness may be in reality decomposed into more elementary sensations which may themselves also be composite. Sometimes the composing elements are con- scious : but oftener, although they are real, they escape consciousness absolutely. 2d. Two sensations which ap- pear in consciousness to be quite independent of each other and of absolutely different quality, may differ, really, only in the number, intensity, or order of their composing elements : differences in quantity in the ele- ments may become differences in quality in the con- scious sensations. Spencer and Taine ' may be quoted in support of these laws. From the use of the wheel of Mivart re- volving once in a second and having a thousand teeth which strike successively upon a metallic tongue and give a continuous sound, while a single tooth is not heard unless immediately followed by a second, Taine argues that the sensation of sound lasting a second is made up of a thousand minute sensations. So the sen- ' Spencer, loc. cit.; Taine, Intelligence. THEORY OF UNITY OF COMPOSITION OF MIND. 103 sation of light which lasts a second is composed of a million sensations of the retina. This confirms the first law. It is true and very important, provided we under- stand that the unconscious components are not sensa- tions in any mental sense, and that conscious sensation arises only when the accumulated nerve excitation is sufficiently great to occasion the mental reaction.' In support of the second law, it is said again, that sensations of color may be reduced to three j)rincipal or fundamental colors, and that the timbre of an instru- ment has only recently been resolved into added tones of a lower intensity than the fundamental. From the former fact, says Taine, " nothing hinders our conclud- ing that the elementary colors are themselves composite sensations :" " so the innumerable sensations which we refer to the same sense may arise from a single elemen- tary sensation for each sense." And " from the princi- ples stated, we conclude that the elementary sensations of the five senses may be themselves complexes of the same original elements. ... In this case, we would have only one elementary sensation of different rhythms.'' This primordial sensation Mr. Spencer considers, vaguely enough, a "nervous shock."" Beply. First, as to the analysis of the facts of mind, we may say that no state of consciousness, as such, is composite unless it is perceived to be so. The state of ' See discussion of the unconscious, Chap. IV, § 2. '^ " The subjective effect produced by a crack or noise that has no appreciable duration is little else than a nervous shock. Though vv^e distinguish such a nervous shock as belonging to what we call sounds, yet it does not differ very much from nervous shocks of other kinds. An electric discharge sent through the body causes a feeling akin to that which a sudden loud report causes. A strong unexpected im- pression made upon the eyes, as by a flash of lightning, similarly gives rise to a start or shock. ... It is probable, then, that something of the same kind as that which we call a nervous shock is the ultimate unit of consciousness." {Loc. cit., pp. 150, 151.) " The substance of the soul is resolvable into nervous shocks" (156). 104 SSJVSATION. consciousness depends upon the nature of the excitation, at the centre, whether continuous and single, or discon- tinuous and complex. A musical chord, for example, is composite and is seen to be so. In a sensation of sound from an organ-pipe 32 feet in length, one can dis- tinguish the elementary sounds of which it is composed. But we cannot say that in every sensation of sound last- ing a minute there are a thousand minute sensations, since the thousand external excitations of Mivart's wheel do not reach consciousness as a thousand excitations, but as one. To establish the position, two things would have to be proved : 1st. That the minimum duration of the impression in the end organs does not exceed the duration of the external stimulus. It is quite possible that an external stimulus which lasts a thousandth of a second, corresponds, in the organ, to a movement which occupies a hundredth or a fiftieth of a second. This possibility is maintained as a fact by many physiologists. '2d. It would have to be proved that the minimum dura- tion of the sensation does not exceed that of the organic impression. It is quite possible that in the time which is occupied by a thousand organic impressions there is only time for a hundred or for fifty sensations. Fech- ner's law ' shows a disproportion between the intensity of sensation and its external stimulus ; why should there not also be disproportion in their duration ? The fact of the persistence of images — in sight, at least an eighth of a second — is overlooked. These persistent images tend to form a single continuous excitation, as is seen in the circle of light made by swinging a torch. So of these two presuppositions, we may say that the second is unproved, and the first is false. Further, as to the reduction of the different sensa- tions of a given sense to a single type or to simpler forms, few facts are advanced, and these may be explained ' See below, § 5. TEEORT OF UNITY OF COMPOSITION OF MIND. lOo by a reference again to tlie physical basis of sensation. The fact is cited that the colors of the spectrum united give Avhite,' and that when a toothed wheel is turned rapidly the sound of its impacts is higher than when it turns more slowly: the conclusion being that the sensa- tion white is the synthesis of all the sensations of color, and that of high tones the synthesis of lower. But there is no evidence that in the case of white there is any sen- sation of color at all. On the theory of different ele- ments in the retina which react for the fundamental colors, it is readily seen that the combined reaction of them all will be a form of motion — or chemical product —different from that of any one of them taken sepa- rately. When the colors are seen successively, as in the revolution of a segmented wheel, the persistence of images causes all the elements to be excited simultane- ously. The result is the stimulus for white. There is no stimulus present at all for the colors, and so no sensa- tions of color. The same for the sound of the toothed wheel since, as has been seen, the height of the tone de- pends at once upon the number of vibrations of the sonorous body. In these cases, the fact is a substitution of sensations and not a synthesis. Additional arguments in support of the theory of "^the unity of composition of mind " are drawn by analogy from the general growth of body and mind together and the reduc- tion of body to atoms. It also serves Mr. Spencer in his gen- eral doctrine of evolution, since if mind be developed it must be from a single principle. The evolution of mind is the pro- cess by which "t\\e numerous and different forms of feeling arise from a simple and primitive sensibility." But if evolu- tion is to be used to prove "^ unity of composition," it must first be proved, and this is impossible since mental facts are an important province for the establishing of general evolu- tion. ° If unity of composition fails here, it goes so far to dis- ' See J. S. Mill, Logic, bk. 6, ch. iv, and bk. 3, ch. vi ; also Leib- nitz, Nouv. Essais. bk. 2, ch. ii. '^ M. Rabiersays, Mr. Spencer here attempts to demonstrate obscurum per obscurius. 106 SENSATION. prove general evolution. Prof. Wuudt's effort also to estab- lish " unity of composition " in the mental life, proceeds upon the hypothesis of "unconscious mental elements/' which has already been examined. More recently ' he emphasizes the " unity of apperception/' as if this were sufficient to account for the specific forms of apperceptive activity, perception, con- ception. Judgment. This gives rise to the difficulty already encountered, in accounting for the specific forms of sensation by the general fact of sensibility. § 5. Quantity of Sensation: Psychophtsics. Weber's Law. By quantity is meant intensity or mass. Until quite recently it was considered impossible to measure intensities in sensation, from the fact that they are subjective entirely and we have no abiding in- ternal measure to which to refer them. This difficulty has been overcome by establishing an external unit of measurement, and comparing sensations through it with one another. A relative measurement is in this way attained. This external standard is the quantity of stim- ulus agreed upon as producing a unit of sensation. The external excitation thus becomes the means of approach to the measurement of the internal fact. For example, if the sensation given by the weight of one gram on the back of the hand be taken as the unit of sensation for pressure, other sensations can be compared with it, in relation to their respective excitations. This procedure has actually been carried out in those of the senses most accessible to experiment and the following law formu- lated, known as Weber's laio : In order that any sensation may increase by quantities always equal, the excitation must be increased by a constant fraction of the excitation itself; or, Ihe excitation must groiv in geometrical progressioyi (1, 2, 4, 8), in order that the sensation grow in arithmetical progres- ' See Ribot's exposition, German Psychology^ p. 214 ; also Wundt, Plxys. Psych., 2d cd. THEORY OF UNITY OF COMPOSITION OF MIND. 107 sion (1, 2, 3, 4) ; or yet again, tlie sensation varies as the logarithm of the excitation.' In arriving at this law, it was necessary to show that the smallest perceptible difference between two sensations of the same sense, requires a constant fractional increase of tlie smaller excitation. This has been shown with reasonable exactness for moderate degrees of intensity of sensations of sight (yiTr)? touch {\), and sound {I). In dealing with high intensities, the proper working of the organ is deranged and the results vitiated; as with very bright lights. In the case of taste and smell, the difficulties of isolating the sensation and measuring the amount of the stimulus have been almost insurmountable. Three distinct methods of arriving at the smallest perceptible difference of sensation are em^^loyed, all of which depend upon the subjective estimate of the person experimented with as to the equality of two stimuli, such as weights or lights.^ The scale of sensation values has its zero or vanishing point at the smallest ferceptihle sensation for each of the senses. Hence the necessity of instituting another series of experiments on all the senses to discover this value. The point at which a growing excitation first begins to be felt as a sensation is called the tlireshold value of the excitation and the sensation is said to be at the threshold.^ This point varies very greatly according to the conditions of the senses as to exhaustion, and the state of the mind, as preoccupied or attentive. ^ ' Fechner. 2 See Ladd, loc. cit. p. 364. ^ This expression was introduced into Psychology bj^ Herbart. •* Upon these two classes of data, smallest perceptible difference of sensations and smallest perceptible sensation, the logarithmic law of Fechner is based. Assuming that the diilerences of sensation to be barely perceived are infinitesimal quantities, and that the difference in the excitation is also infinitely small, as compared with the whole stim- ulus, we may, by the calculus, equate differentials and write (making d^ increment of sensation, de increment of excitation, and k the propor- tional constant) , ds = k — , e whence, by integration, 8 = k log e ; or, the sensation varies as the logarithm of the excitation. The thresh- old value then being given, the scale is built up. 108 SENSATIOK Besides its application to the regular sense perceptions, Weber's law applies, with the same limitations, to the estima- tion of linear distance ' and to the judgment of the flight of small portions of time.'' In order that I may judge a line twice as long as another, it must be really more than twice as long; and in estimating five seconds I make the time too short by about one fourth.' The distinction between the affective and presentative elements in sensation is strongly brought out by these re- searches in respect to quantity. From the nature of this dis- tinction, we would expect that exact research could be applied to sensation only in the degree and aspects in which it is pre- sentative, i.e. capable of appreciation in terms of objective reference. The affective element, on the contrary, is a purely subjective quantity and is beyond all scientific approach. This is borne out in fact. The senses which confirm Weber's law are sight, toucli, and hearing, ancl these have been seen to be most presentative. But the law is not proved for taste, smell, organic sensation, which are most aSective. And this relation is further confirmed by the fact that in the presenta- tive sensations the law does not hold for high intensities; since then there is a powerful reaction of the affective element, as pain under bright light, or shock when a loud sound is heard. That is, the law holds of the presentative senses only when they are most presentative. So the criticism that quantitative measurement of sensation is impossible," is true only for sen- sation proper as distinguished from sense perception. The same is true also as regards the duration of sensation.^ The interpretation of Weber's law has occasioned much discussion. How are we to construe the fact that the sensa- tion, which must be considered as effect, does not increase proportionally to the stimulus, Avhicli is cause? Three differ- ent views are held: first, that this relation is an ultimate law of the relation of body and mind; " second, that the dispropor- tion is due to the activity of apperception and is strictly psy- ' Cf. Bully, Sensation and Intuition, pp. 50-60. ^ See Glass, PJtilos. Studien, iv. p. 433; also James, Jour, of Specu- lative Philos., Oct. 1886. ^ This can be readilj' shown by counting seconds with the eyes on the second hand of a watch, and then attempting to repeat it with the eyes closed. Below 1 sec, the time is judged too long. * Kant, Bering, Delbceuf. 5 Cf. § 6, below. * Fechner. EXTENSIVE OR MASSIVE SENSATIONS. 109 chological ; ' and third, that the disproportion is due to the loss of excitation energy in the physiological processes involved, the processes of transmission by the nerves and central stimu- lation. This makes the central process the cause of the sen- sation, instead of the perijaheral process, and the law of causa- tion holds. This is on many accounts the best interpretation.^ Extensive or Massive Sensations. The quantity of sen- sation, considered as intensity or intensive mass, is to be distinguished from its quantity considered as extensify or extensive massiveness. If I paste one postage stamp on mj hand and then another beside it, the sensation is in- creased in the second case in extensive massiveness, but not in intensity. This distinction in quantity is possible for all the senses, but only when there are coexistent sensations of the same sense which do not coalesce to produce a higher intensit3^ It seems to depend upon an extensive organ of stimulation, skin, retina, which is stimulated over a more or less extended area. It is ex- perienced in putting the hand in water, or in hearing, at the same time, a continued musical note and a harsh noise. The difference between the two kinds of increase in sensation is distinct enough to require separate men- tion. § 6. DuKATiox OF Sensation and Thought : PSYCHOMETllY." The measurement of the duration of mental acts was begun by Donders about 1861. Before his time, it was generally admitted that psychic processes must be con- strued in time, and the question of the rapidity of thought ^ Wundt: defended by Grotenfelt, Das Webersche Oesetz. "^ See my five reasons in support of this position in Presbyterian Be- view. July, '87, pp. 437-438 : supported b}' work of F. C. Miiller ; see Amer. Jour, of Psych., vol. i. p. 185 ; cf. also Ward, in Mind, i. p. 452. ^ The substance of the text of this paragraph was written for Dr. McCosh's Psychology (vol. i. pp. 147-8), and is republished with his consent. 110 SENSATION. was discussed from the standi^oiut of general conscious- ness. We are conscious of tliinlcing sometimes faster, sometimes more slowly. But this subjective estimation of time was vague, just as that of quantity was vague, for want of a constant measure in the inner life. Since the discoveries of Helmholtz and others, as to the ve- locity of nerve transmission, it has become possible to arrive at a determinate expression for the time necessarj^ for different sensations and for some of the simpler ap- percejDtive functions. I. Beginning with simple sensation, the case is briefly this : let the skin of a man in normal conditions be pricked and let him sjjeak as soon as the pain is felt, or let a word be spoken and let the subject press a button as soon as he hears it. The period that elapses be- tween the two events, in any such exj)eriment arranged for two senses, is called the simple reaction time and va- ries from -g- to ^ sec.,' according to the individual and according to the conditions of the experiment. Upon consideration, it is readily seen that this period may be divided into three parts : first, sensor nerve trans- mission to the brain centre ; second, the mental process of sensation and volition ; and third, motor transmission to the organ moved. Now since the velocit}- in both the motor and sensor nerves is known, we reach by subtrac- tion the time of the mental act. Instruments are used by means of which differences to the ten-thousandth of a second are noted. By this analysis of the simple reaction time, we arrive at two general princijDles : a. The simplest mental act occupies an appreciable period of time. b. The purely physiological or transmission time is less than half of the entire reaction.'^ Consequently the time ' The result of four buudred experiments upon myself, after consid- erable practice, was .125 (^) sec. - This was conjectured by Darwin from the fact that we wink the PSTCHOMETRY. Ill taken ujo by the sensation and motor impulse varies slightly either way from J^ sec. This cannot be called purely mental time, however, for the central physical change goes on at the same time. II. Passing from sensation to the reproduction of ideas as memory pictures, it is concluded from experi- ments conducted similarly : «. The time occupied in the reproduction of a state of con- sciousness is longer than the time of its production. b. The time of reproduction depends upon the degree of attention given (1) to the original sensation, (2j to the repro- duction.^ III. A third operation on which many experiments have been made is that of distinction or discrimination. To experiment ujdou sight, let two colored lights be shown, the subject understanding that he is to react by speaking or pressing a button only when he sees the color agreed upon beforehand. This involves first a comparison and then a judgment, with volition. By an easy process, the purely physiological time is elimi- nated, and the duration of the mental act is found to be -gig sec. (Kries) to yL sec. (Wundt). The discrimina- tion is easier when the sensation is of high intensity ; and since, in all reactions, the signal must be discrimi- nated from other sensations in consciousness, we have the principle that the duration varies inversely as the strength of the stimulus. IV. Experiment has rendered service, also, in defin- ing and confirming the laws of association. The time of a simple association is found to be f sec. to | sec. KeiDe- tition greatly shortens the time by strengthening the association. V. A fifth class of experiments relates to the logical eyes without having a change of sensation from light to darkness. — Zoonomia, i. p. 24. ' On the general effects of attention, see below. 112 SENSATION. judgment of subordination, i.e. from genus to species. It is found that the time is longest when the subject is abstract and the predicate a more general notion (man is intelligent), shortest when the subject is concrete and the predicate a less general notion (the house is red). The average of a great number of experiments gives the time about 1 sec. This is imjjortant as illustrating the growth of the general and abstract notion from the concrete, and indicates that the order of instruction of children should be the same. It should be said that these results are true only in an average sense and under normal conditions ; and further, that they represent only a single type of our every-day mental pro- cesses, that of more or less concentrated attention. The fact that the subject of the experiment must take part in the ar- rangements and concert hisactionswith those of others, makes it impossible to obtain results without the attention. In life, however, most of our actions are not foreseen, and our attention. is draAvn to sensations by their occurrence, not beforehand. The degree of attention, however, may be somewhat varied and the results noted. The bodily states also greatly influ- ence the duration of mental acts. Fatigue and other unusual physical conditions tend to lengthen the reaction time. The senses with which the most exact results have been obtained are sight, hearing, and touch, the most representative senses : Avith taste and srnell the mechanical difficulties are very great. In dreams, the ascertained durations do not seem to hold, since the flow of presentations then takes on, in many cases, enormous rapidity.' Effect of Attention upon the Duration and Quantity of Sensation. We have already noted the general law that attention increases the intensity of sensations.^ It is at once seen that this principle interferes with the applica- tion of Weber's law, since a given stimulus is felt more strongly if attended to than otherwise : so that in com- ' For attempts to determiue the perception, apperception, and will time separately, see references given by Ladd, Phys. Psych., cli. viii. This chapter of Ladd's, with its references, is the latest and finest English summary in this department. 2 Chap. V, § 2. PSYCHOMETRY. IVS paring sensations by their excitations it is necessary to keep the attention constant in the two cases. The effects of attention uj)on the duration of sensations is even more marked. In general, attention diminishes the time necessary for the reaction. The shortest times are ob- tained by concentrating the attention. To such an extent may this give rise to expectation of the excitation, that it is sometimes anticipated, the reaction of the hand, for example, being given before the signal is made. In the hypnotic state, where the attention is strongly fixed, the time is shortened. Further, if the attention be fixed upon the reacting sense rather than upon the receiving sense, the time is shorter.' This concentration is esj)e- cially necessary at first, before the muscular reaction becomes automatic. The function of attention as a com- paring and relating activity, that is, as apperception, is strongly seen in the experiments to determine the dis- tinction time, where very great variations are due to changes in the energy of attention. The shortening of the reaction time by attention has evident pedagogical applications. Effect of Duration upon the Intensity of Sensation. Within short periods, the intensity of a sensation is di- minished if its stimulus be continued. This arises from the accommodation of the organ to the stimulus. It ap- plies especially to slight pleasurable or painful stimuli. Long-continued stimulation, however, from exhaustion ' This I found in my own experiments before seeing reference to N. Lange, by Cattell, Mind, Jan. '88, or Wundt's 3d ed. It is probably due to the fact that when the attention is directed to the re- ceiving sense, the idea of movement becomes dim and the attention must be recalled to it, that the movement may follow : while, in the other case, the idea of the proper movement is kept in apperception, while the signal, if distinct, carries its own discrimination, by what Mr. ^\i\\j Q?i\\?, preperception {Outlines, p. 227), without the readjustment of attention. Lange 's work is now published in Philos. Studieii, iv. 4 ; see also Amer. Jour, of Psych., May, '88, p. 531. 114 SENSATION. of the organ, becomes increasingly intense and painful ; and sensations at first pleasurable become painful under this condition. § 7. Tone of Sensation. By tone of sensation is meant the feeling of pleasure or pain which accompanies it. It represents somewhat in all sensations, and in the higher senses almost entirely, the aflfective element. Pleasure and pain are onlj^ and wholly afi'ective. Our whole sensational exj)erience is accompanied by pleasure and pain and so has tone.' § 8. Localization of the Sense Functions in THE BkAIN. The question as to v.hether there are local areas in the cortex or gray matter of the brain, which are espe- cially active in the exercise of the sense and motor activi- ties, is of great importance for general psychology. Ex- periments have been very conflicting in their results, but it is now generally admitted that there are a limited number of well-ascertained areas. The motor functions are grouped around the fissure of Rolando, though it is impossible to tell whether the failure in movement which accompanies destruction of this region is due strictly to impairment of motor power," or of tactile and muscular sensibility,' or of both. The speech centre is the third of the frontal gyres of the left lobe. The areas con- cerned in the sense functions are in more doubt. Oil Sensation, consult : in general, Wundt, Pliysiologische Psy- cliologie, ch. vn-x ; McCosh, Cog. Powers, bk. 1, ch. i ; Carpenter, Ilental Physiology, ch. iv ; George, Psychologie, p. 51 ; Porter, Hu- Qnan Intellect, ch. iv ; Ladd, Physiolog. Psydiol. , pp. 303-355 ; ' Pleasure and pain come up for full discussion in the treatment of feeling. The much-discussed question of the "indifference" of some mental states to either pleasure or pain is also deferred. - Ferrier. 3 Munk, Schiff. CEREBRAL LOCALIZATION. 115 Volkmann, Lehrhuch der Psychol., §§ 33-48 ; "Waitz, Lehrhttcli der Psi/ch. , §^ 8-10, and Grundlegung der Psychol. , })}). 1 02-1 1 1 ; Drobisch, Psychologie, §§4-13; Fortlage, System der Psychol., §§ 78-80; Stumpf, Tonpsychologie ; Scrgi, Psychologie Physiologique, I. ch. lii-vi ; Kichet, Recherches snr la SensibiliU ; (Temperature Sense) Donaldson, Mind, x. 399; Bernstein, Five Senses of Man ; Morell, Elements, ch. lil ; Delboeuf, Tlieorie generale de la Sensibilite ; Sully, Psychology, ch. v ; Rabier, Psychologie, bk. 2, ch. ix-xi; Bain, Senses and. Intellect, p. 117. For references on the individual senses, see Dewey, Psychology, pp. 78-80. On Psychometry : Wundt, Phys. Psych., ch. xvi ; Ladd, Phys. Psych., pp. 468-497; Ribot, Germ. Psych., ch. vii ; Sully, Sensation and Intuition, III, A, I ; Sergi, Psych. Phys., bk. 3, ch. iv ; Cattell, Psycho metrische Untersuchungen ; Philosophiscfie Studien (numer- ous articles). On Psyclioph.ysi.es : Wundt, Phys. Psych., ch. viii ; Ladd, Phys. Psych., pp. 356-381 ; Ribot, Germ. Psych., ch. v; Sully, Sens, and Int., Ill, A, II ; Grotenfeldt, Das Webersche Gesetz ,\Tix\\\\evY, Revue Pliilosophique, xxi. 386 and xvii. lo ; Delboeuf, Elements de Psy- chop. and La Loi Psychophysique ; Fechner, In Sachen d. Psychop. and Revision d. Hauptpunkte d. Psychop. ; G. E. Miiller, Grundleg- ung d. Psychop. ; Fechner, Eleynente d. Psychophysik ; F. A. Miiller, Das Axiom d. Psychojyhysik ; Philosophische Studien (numerous articles). On Cerebral Localization : Ladd, Phys. Psych., pp. 239-302 (with references); Calderwood, Mind and Brain, ch. iv; Sergi, Psych. Phys., ch. iii-vi ; Charcot, Legons sur les Localizations ; (Aphasia) Huylings-Jackson, ^rawi, 1.304 and ii. 203 and 323; Luciani, Brain, VII. 145. Further Problems for Sttidy : Methods of psycho-physical study; Experimental approach to the senses of smell and taste; Application of mathematics to psychology ; Education of the senses. CHAPTEE VIII. PERCEPTION. § 1. Definition of Perception. The theory of perception is perhaps the most impor- tant as well as the most difficult problem of psychology. The interpretation of the higher, processes of mind rests upon it and it underlies the bod}^ of our general philosoph3\ The great philosophies of the world take their rise from initial differences in the method of construing perception. Lea\ing the general problems of the theory of knowledge to metaphysics, we have to do only with the process of perception, considered as an operation of mind in at- taining knowledge of the external world. That is, we have to answer the simple question, " How do we arrive at the knowledge of individual objects localized in sj)ace and time ?" In viev,' of the terms of this question and of the analysis which follows, we may define perception in a general way. Perception is the apperceptive or synthetic activity of mind loherehy the data of sensation take on the forms of rep- resentation in space and time : or it is the process of the con- struction of our representation of the external world. Psychologists have generally been accustomed to distinguish between two forms of perception, as simple and acquired: meaning by simple perception, the presentative or knowledge element in sensation, and by acquired perception the derived and synthetic products of tlie apperceptive faculty. This dis- tinction is a true one, since tlie essential fact in both cases is that of presentation. Yet while recognizing this truth, it is difficult to separate simple perception from sensation. Indeed, as has been seen, the former is only the form of some sensa- tions, not an independent thing, and it is more satisfactory to 116 AlfALTSJS OF PERCEPTION. 117 treat it in that connection. Perception, then, is limited in this chapter to the higher or synthetic process as it takes place in apperception.' This has also the further advantage of distinguishing more sharply the two forms of knowledge as to their origin. The presentative element in sensation is as immediate as the affec- tive and the two should be treated in the same category. Knowledge thus finds its bases as original just as sensation does. And synthetic perception only indicates knowledge in •a more advanced stage. § 2. Analysis of PERCEPTioisr. A little reflection leads to the conclusion that our per- 'ceptiou of the external world is a matter of mental con- struction. All advance into the region of mind must be through mental states. The characteristic of mind is con- sciousness, and nothing can enter the domain of mind except through the mediation of consciousness. This is seen in the fact that our images play in consciousness in such a way as sometimes to deceive us in regard to the external world. When the eye is deranged, the mind is deceived in regard to colors and distances. When we have a cold, our taste is impaired. When the hand is amputated, irritation of the nerve ends is still localized in the hand. This amounts to saying that the mental picture which in every case is necessary to the percej)- tion of the object, is impaired or dissipated. The nervous system also intervenes between the mind and the world, and the proper activity of mind in representation depends upon the normal functioning of this system. This fact, that the mind deals with its images primarily and with external realities only through these images, is best seen when w^e consider that all mental states are intensive modifications of a thinking subject, and that the percep- ' Cf . Sully, Outlines of Psychology, cliap. vi. There is undoubtedly need for some word like Prof. Laurie's Attuition to designate the original knowledge element in sensation, in distinction from the active synthesis of Intuition. See Laurie's Metaphysica nova et vetusta, p. 6. 118 PERCEPTION. tion of the external world, liowever real that world be, with its conditions of space and time, is possible only by some power of mind whereby these conditions can be mentally reconstructed and the intensive data of expe- rience cast in the forms of this reconstruction. As a process, perception proceeds upon the presenta- tive element already found in sensation. In connection with each sense this element has been emphasized, and it forms the basis of all our finished perceptions of sense. For example, the representation of extension in the perception of an orange, makes possible the synthesis of affective states, smell, taste, color, which the percept involves. The construction of the representation of the external world involves three subordinate but synchronous and essential operations, which we may call, respectively, Differentiation, LocalizatiGn, and Intuition. And each of these, in the perceptive synthesis, has reference, first, to the perception of our own body, that is, of the intra- organic, and second, to the perception of objects foreign to our own body, that is, of the extra-organic. § 3. Differentiation. The beginning of all life experience is probably, as has been already said, a state of general undifferentiated feeling. The affective consciousness, at this earliest sta,ge, may be called an undifferentiated sensory continuum. This has been described briefly in the section on the groAvth of consciousness. There are, at this beginning of sensation, no distinct forms for the different senses, no feeling of externality, no perception either of one's own body or of things. It is easy to imagine one's self in that condition. All physical feeling is then vague, like the internal sensations which we cannot localize nor trace to their causes. It is probable that the muscular sense, with touch, constitutes almost the whole of this experi- LIFFERENTIATION. 119 ence. Tlie earliest transition from this state of general sensation is also probably due to the muscular sense, through clififerences of intensity in feelings of resistance, and through the sense of locality in the body. The special organs of the other senses are more complex and must be adapted to their function of reporting impressions from without. Yet no step toward a real differentiation of sensations can take place till an active reaction of mind is possible in the shape of attention. As has been seen, definite sensations are unnoticed and not distinguished without attention. At first this attention takes the form of passive apperception. Apperception is itself the differ- entiating and defining activity. By it the unordered and chaotic mass of sensation, which is thrown upon the help- less subject, is divided and distinguished and made dis* posable by the further processes which constitute its completed activity. As this differentiation proceeds, each sense becomes a distinct source of affective experi- ence, somewhat in the following order of development : muscular sense, touch, temperature, light, sound, taste, smell, color. The mere fact of differentiation, however, can give us no feeling of difference between our own body and a foreign bodj'. This distinction can arise only after we begin to localize our states ; and even then all these states are located first in the bodily organ through which they arise in consciousness. It sliould be borne in mind that these stages in the process of perception are distinguished logically and in kind, and not chronologically. In a general way, we may suppose that the simplest facts of mind are earliest in their development, from the fact that the more complex must proceed upon the simple. Yet we find processes of a higher order present and necessary in these early stages. For example, it is difficult to see how this differentiation of presentations can be permanent, as a mental classification of experiences, without memory both in its retaining and its reproducing function.* The divisions neces- 1 See Chap. IX. 120 PERCEPTION. sary to the treatment of the various aspects of mind should not lead us to carry exclusive divisions into the mind itself, § 4. Localization". The second stage in the synthesis which is called perception is localization. By this is meant the mental reference of a sensation to a locality in space. In the finished product of the perceiving faculty we apprehend things as in space. Here is a new idea or form, of which, in the purely intensive character that sensation at first 23resents, we find no intimation. Whence does it arise, and to what factor in the perceiving process is it due ? This is the question of the origin of the idea of space : one of the problems most discussed in general philoso- j)hy, and one to which contemporarj- psj'cliology is fully alive. The origin of the idea of space is more discussed than the •origin of the idea of time, because, in the first place, it is the form of outer as opposed to inner phenomena, and according as its solution is idealistic or emjiirical, our theory of the ex- ternal world finds its essential character. The idea of time, however, is bound up alike with phenomena of both spheres of experience, and whatever its solution, no advantage is given to one sphere over the other. The former question also j^re- sents more richness and complexity of data, and seems to afford more chance for a complete solution, from the very fact that it offers more varied alternatives. Further, two things should be said in referenec to tiie true manner of approaching this question. First, we should bear in mind that it is tlie psychological and not the metaphysical problem with which we have to do. It is our business to ask, whence the idea of space ; not, what is space. The meta- physical problem may remain unanswered after our psycho- logical theory of space is complete, except in so far as the ori- gin of the idea may require a doctrine of external reality. In this latter case, we are Justified in using any data which a rea- soned metaphysic may afford, understanding, however, that these data must conform to the results of our empirical analy- sis. And second, it must be remembered that the question of origin is a question of f/e)iesis, or lieginnings, not a question of Qiahire, or quality. The great difficulty with the older dis- THE PERCEPTION OF SPACE. 121 cussions of this question is, that space in the abstract was brought into court, as a finished world-form of infinite ex- tent: while in reality, psychology has to do merely with con- crete perception and the space-form of that perception. In- stead of starting with a finished space and asking ourselves how it is that we perceive bodies in it, we must begin with our individual perception of body in all its real complexity of matter and space-form, and ask how we can analyze this com- plex fact of experience in such a way as to account for its space-form.' The Perception of Space. It is generally agreed by psychologists that our first experiences of space are con- nected with the muscular and touch sensations of our own body. As has been said, the sensory continuum, before all differentiation, is largely muscular. The "beginnings of difiereutiation seem at once to implicate the extensive or massive quality of sensation. There is a yague feeling of whereness in this early muscular sen- sation, and it becomes more definite as the extensive or spread-out sensations from the skin become broken up in localities. But at this beginning of space-experience the question confronts us : How can excitations of the skin and muscles, which are transmitted in the form of molecular action through a homogeneous nerve substance, and wdiich have thereby lost their local coloring, report their locality to the subject : and further, how% if they preserve this local coloring in such a way as to jDresent specific differences of motion at the central bureau, can these differences be reported to the mind, which is an nnextended thinking principle capable only of intensive states ? There is only one answer which does not either beg the question at issue or overlook some one of its essential conditions : i.e., The mind has a native and original capacity of reacting upon certain physical data in such a ivay that the objects of its activity appear binder the form of space. ' See Croom Robertson, iii Mind, Li. p. 418. 123 PERCEPTION. In the following paragrapli, the relation which this posi- tion bears to other theories will be apparent. Kecent discus- sion ' tends clearly to emphasize the fact that no purely em- pirical explanation is sufficient to account for the extensive form of sensation. Be the data what they may, and be they as important and essentia! as external data always are in per- ception, there will yet remain the barrier between intensive feeling and extensive thing. This barrier can only be broken down by an exercise of some form of activity whereby space is mentally reconstructed ^ upon the basis of the data of sense. It is objected to this view, that it leaves the problem as obscure as at first. What is this mental reconstruction? This is true, but the same may be said of any other process of mind. What is perception in general? Wliat is sensation? A mental reaction upon a nervous stimulus. What is space perception ? The same with the added reaction of space-form. One is as mysterious as the other. But while this is true, this view of the case leaves the question of the data necessary to the perception of space entirely open and thus takes advan- tage of all the results of the empirical treatment of the senses. The mental reconstruction may proceed upon its own data in each of the senses which give us space-form, and it is our part, as Lotze says, to discover these data and to borrow from physiology all that is attainable and useful in the premises. What these data are for the different extensive sensations, we next inquire. This is seen to be a form of nativism, but a nativism purely of process, not of product. The power to perceive space is as native as the power to perceive anything else; but this does not mean that space is native to the mind any more than trees are or music. Objects are given to us in space, and space is given to us with objects; they are inseparable, and both are, in thought, the product of the synthetic activ- ity of apperception. Data for the Perception of Space. In the perception of space relations by the muscular sense, touch, and sight, the three senses through which this form is presented, two classes of data seem to be involved. These data are of a physical kind and serve as basis for the mental ' Lotze, Wundt, James. "^ "Wiedererzeugung der Rilumlichkeit," Wuudt, TJieorie der Sin- neswahrnchmung, p. 51. DATA FOE THE PERCEPTION OF SPACE. 123 reaction just spoken of. Tliey are muscular movements and Jocal signs. I. 3Iuscular Movement. Under the discussion of the muscular sense,' the twofokl nature of the sensations in- volved was spoken of. Sensations of efibrt or motor in- nervation were distinguished from sensations of resist- ance. The former of these was seen to be central and the latter peripheral. The latter has its anatomical seat in sensor fibres in the muscles or skin, thus assimilating this element of the muscular sense to pure sensations of touch. Both of these seem necessary to the finished feeling of movement, though feelings of resistance play a predominating role. We learn from cases already men- tioned, that if the feeling of resistance be destroyed, a limb may be moved voluntarily with no knov/ledge of the actual movement, but, on the other hand, the movement of a limb mechanically is felt as movement when there is no voluntary motor discharge. Hence, though we may hold, with Spencer, that space is a succession of resist- ances or, with Hall, that space is primitive in the mus- cular experience, we still find the element of muscular resistance in our first sensations of localit}'. We see below that movement enters also in the perception of tactual and visual space. Inasmuch as feelings of resist- ance involve touch as well as pure muscular experience, the second of our data, the local sign, is brought into jjia}'. II. Local Sign. By local signs are meant specific local differences in the arrangement (Lotze) or structure (Wundt) of the cuticular substance. By these difteren- ces, localities partake in perception of the position they occupy in space. I refer an excitation to my hand or foot: why do I give it such a specific reference? Why do I locate a pain in my right hand rather than in my left? Simultaneous sensations of a purely intensive na- ture, as tastes, sounds, are fused together ; but simulta- KJbap. VII, § 3. 124 PERCEPTION. neous sensations from neighboring points of the skin and retina preserve their peculiar character and rela- tion to one another. As has been said, the first idea of our own body results from muscular sensations which accompany the feeling of effort, and these sensations are vague and confused ; yet even here the feeling of exten- sion is present, also vague and confused. Whence comes it ? It can only come from initial differences of some kind which are perpetuated through transmission to the sensorium. These differences, probably in the skin or sensor nerves, and probably a matter largely of association, afford a second datum for the localization of sensations in different portions of the body. The theory of local signs was first propounded by Lotze, who, however, varied it in its application to the several exten- sive orders of sensation. For sight, he made the local sign consist in the fixed amount of muscular movement which any retinal point must undergo to be brought into the line of clearest vision. This is a different and definite quantity for every point in the retina. In the skin, the local sign, for Lotze, was the combination of light accessory sensations which are provoked in immediate connection with the point of contact. There would be a varying amount of radiation of stimulus in the skin according to the varying structural con- sistency of the parts over which the skin is stretched, as bone, muscle, ligament. This hypothesis found development in the more natural position,' that the local sign was an implanted peculiarity in the structure of the skin itself. A further the- ory, very widely adopted, and suggested by Czermak, makes the local distinctions in the skin due to the ramifications of the spread-out nerve fibrils, each such nerve end reacting for its own position and being thus a local sign. ^ This position is most probable. It is supported by the fact already cited, that the sensibility of the skin to local differences varies greatly in dif- ferent parts of the body, and may be increased by the fixing of the attention, by exercise, and in the hypnotic state. These latter conditions tend to bring into play finer elements of the ramifying nerve, and thus to diminish the distance be- tween the sensitive points. And the same facts tend to refute ^ Meissner. - See Sully, Outlines, p. 119. DATA FOE THE PERCEPTION OF SPACE. 125 the theory that the units of tactual feeling are found in We- ber's "circles of sensation," ' Besides the general consideration that some such hypothe- sis as that of local signs is necessary to the case, there is di- rect evidence of the existence of these signs. The fact of varying local discrimination in the skin has been mentioned; it is also true of the retina. The relative discrimination of localities grows less delicate as we proceed from the centre to the edge of the retina/ and colors lose their intensity as they are projected more and more upon the side of the retinal sur- face.' The quality of massiveness or extensity of sensations of touch and sight depends upon the simultaneous independent excitation of units of sensation, and can be accounted for only on the assumption of some characteristic by which these units are kept distinct. If the skin of the forehead be bent down upon the nose and grow there, its irritation is felt still at the forehead. The same is seen in the retina in certain patholog- ical affections, in which the retinal elements are displaced: the irritating points of light falling upon these elements are localized Avhere they would be seen by the healthy eye.^ But the fact of local signs is not sufficient to account for the perception of space. Whatever these signs be, the color or local tone they give is a modification in quality alone, an intensive change in the sensation in question, and there still remains the necessity for a mental reaction whereby this in- tensive sensation, modification or sign is construed in exten- sive form. How can we infer differences of position from differences of pure feeling ? Let a sensation of red be modi- fied in any way whatever as to its redness, and we are still absolutely in the dark as to its location on the riglit hand or the left. Admitting the concomitant sensations of Lotze, one of two things must be true: either these concomitant sensa- tions coordinate themselves in space in virtue of their own quality or they do not. If they do thus coordinate them- selves, why could not the original sensations coordinate them- selves ? If they do not thus coordinate themselves, what help are they to us in this coordination ? They must be only data by which the coordinating activity of mind proceeds m the matter of space perception. ^ ' On the geueral theory of Local Signs, see Ribot, German Psychol- cgy, chaps, iii. and iv. ■^ See Sully, Sensation and Intuition, p. 54. 3 Wundt. * Wundt, Phys. Psych., 3d ed., ii. p. 88. * It is not necessary, however, with M. Rabier (p. 63) to deuy the 126 PERCEPTION. Synthesis of Data : I. Tactual Space. The two kinds of data mentioned are found in all spacial localization. From the fact that thej are thus found, that they enter necessarily into the nature and functions of the sense organs by which space is reported, and that the non- extensive sensations are wanting in the physical condi- tions which they represent, we are led to conclude that they are at the basis of the reconstruction of space. Upon this basis the mental reconstruction of spacial position proceeds. Locality being thus given, its defini- tion becomes very exact in experience. Feelings at first vaguely localized are given precise spacial position. This is rendered easy by the exploring power of active touch. If left to passive touch from external objects, it is un- likely that v/e would ever arrive at a clear conception of the extent and form of our own bodies. But hy free movement of the hands, with active touch, the relative parts are explored. This is evident from the fact that localization is most exact in the parts of the body most open to active touch and freest in movement, as the hand, arm, tongue, as contrasted with the back and cheeks. This process is also aided by our larger movements and their reversal, and takes place with rapid advance in early childhood. It should be noted that the idea of our own body is not complete until we already have an idea of foreign body. Such a complete idea involves the action of one part of the body upon another, as the feeling of one hand by the other, to which it is really foreign. It is probable also that sight, as of the hand considered as a foreign body, makes the idea of our own body more distinct. This is seen in the very vague and indistinct ideas of size and distance on the part of those who are born blind. utility of local signs, as giving us only another series of sensations to explain ; for, liowever obscure their rule may be, they do enter into our perception of space, as is seen in the fact that sensations for which there are no such signs have no space-form. VISUAL PERCEPTION OF SPACE. 127 II. Visual Perception of Space. As lias been already intimated, the same data enter into the visual perception of space, muscular movement and local sign. The evi- dence of the presence of local signs in the retina has also been adduced. Ever since the time of Berkeley,' it has been generally admitted that the original perception of the eye is of a colored surface onl}^ : that is, that the eye has no immediate perception of depth or distance. This is shown most decisively by cases in which sight has been restored to those who were born blind. About a dozen cases of the removal of congenital cataract from the eyes of persons of some age are on record,'' the oldest and most famous being the Cheselden case.' In each of these cases the eiddence is very clear. When sight is restored the patient sees everything in the same plane : there is no distance, no relief, nothing but a colored sur- face, and this surface seems to be near the globe of the eye. The blind man on whom Cheselden operated said that objects touched his eye. Home's patient said the same of the sun and of the head of the physician. The patients of Nunnely and Franz had the same expe- rience. The muscular movements of the eye are of extreme delicacy and variety. There is for everj' point of the retina a fixed coefficient of movement necessary to bring that point in the centre of clearest vision ; and when such a point, right, left, above, below, is excited there is at once a tendency to revolve the ball of the eye in such a way as to bring the line of vision tlirough this point. This represents a given degree of central innervation or muscular strain. Since ocular movement jjrecedes vision, there are no means whereby such movement can ' Berkeley, Theory of Vision. ' See Naville, Revue Scientifique, 1887, p. 943. " See details of Clieseldeu and other cases in ]^TcCosli's Psychology, vol. I. p. 45. 128 PERCEPTION. be eliminated from the data of synthetic activity of mind whereby we see things extended ; and further, the influ- ence it exerts in localization is seen in the fact that if one of the muscles of the eye be destroyed, so that no move- ment follows its stimulation, objects are localized as if this movement had taken place.' The necessity for such a synthetic activity is the same as in the case of touch. Sensations from the extended surface of the retina and from its movements over the visual field can be only in- tensive modifications of consciousness, which are appre- hended under space-form by the mind's own reconstruc- tion. The process in this case is the same as in touch and the muscular sense, though we are no longer con- cerned with the origin of the notion of space. Spacial perception by touch and the muscular sense j)recedes spacial perception by sight. The idea, as a mental ac- quisition, is probably gained roughly before we see at all. But this does not impair the fact of spacial per- ception by sight. Having the idea of space, why do we clothe the data of sight with this form, and why do we not thus clothe the sensations that do not have it in our finished intuition ? Evidently because sight offers also the data which we found previously necessary for the mental reconstruction of space. TJie fact that tactual precedes visual space renders it ex- ceedingly difficult to determine what is peculiar to vision. We can reach tactual perception alone by observing the blind, hut there are no cases of patients having sight but wanting in skin and muscles. For this reason, those who find in sight ' See references given by Wundt, Phys. PsycJi., 2d ed., ii. p. 91, and I. p. 375: "For instance, one suffering from paresis of the right external muscle of the eye, where the muscle is able by the lUmost effort to effect a lateral movement of 20°, locates an object, which in reality is only 20° distant from the median plane, at a point as far out- ward as corresponds to the utmost outward movement of the normal eye, and when asked to touch the object places his finger far beyond it to the right. " PRESENTATION OF FOREIGN BODY. 129 an immediate perception of the third dimensiou have no data of a positive kind to prove their point.' Presentation of Foreign Body. The distinction be- tween our own and a foreign body arises very early in child life and is not subsequent to the completed idea of our own body, As we have seen, the perception of our own body as extended involves both distance or move- ment, and resistance. In the primary feeling of resist- ance, we have the beginning of the perception of foreign body. The amount of movement or distance, measured in feelings of innervation, indicates roughly, at first, but with great precision later, the localities of objects around us in reference to our ov.-n body. This is greatlj- aided by active touch. We feel round a body and give it the third dimension, which we have already found to be an attribute of our own bod}^ The distinction between our own members and other objects is further assisted by the phenomenon of double touch ; ^ that is, the two sensations of touching and being touched, when we come in contact with our own skin. In paralysis our own limbs are to us as foreign bodies, inasmuch as the sensation of active touch alone is present. The general law which regulates the localization of sensa- tion is this, that sensations localize themselves by association with their cause or condition in the organism. Consequently, tactual and visual sensations are at first associated with their- respective organs. But, on the otlier hand, tactual and, as shall appear later, visual sensations often involve movement of the hands to seize or feel, and of the eyes and head to per- ceive distinctly. This involves distance and adjustment to that distance. So anothei- set of associations comes into play, and the sensations are referred secondarily to objects away from the organism. This secondary association becomes the controlling one from the fact that, as our experience extends, ' James, Perception of Space, 3 articles, Mind, '87 ; also Hering and Janet. 2 So Condillac. 130 PERCEPTION. the reports of the different senses gather around these points of external reference and make them permanent. Visual Perception of Distance. The yisual percep- tion of distance or depth 23roceeds upon the tactual and muscular perception of distance. It consists in the ac- quired interpretation of light and color diiierences in terms of distance already given by the skin and muscles. The original colored surface presented in vision is pro- jected more or less distantly, according as its lights and shades are associated with a greater or less muscular or tactual coefUcient, This is seen in the fact that the original errors of sight, in respect to distance, are rec- tified by touch and muscular movement. In the Trin- chinetti case, the patient at first " attempted to grasp an orange with her haiid very near the eye, then, perceiving lier error, stretched out her forefinger and pushed it in a straight line slowly until she reached her object." Other patients have done the same, when first restored to sight.' This interpretation in terms of muscular and tactual feeling becomes, in later experience, a matter of the sensitiveness of the eye itself. Its own mechanism of movement and retinal reaction gives data by associa- tion for the perception of depth. A number of factors enter in the mechanical adjustment of the eye to sight at different distances. Among them we may mention: a. A muscular strain when the object is near, due to the slight contraction of the pupil and the swelling of the anterior surface of the crystalline lens. This is called the sensation of accommodation, h. Difference in an object when seen near or far with both eyes. The difference in the angle of vision of the two eyes, enables us to see parts of the sides and thickness of the object gazed at, and this datum of depth varies with the distance, c. Strain arising from the varying angle made by the lines of vision of tlie two eyes. When the object is near, the eyes turn toward each other; this is known as the sensation of convergence, d. Dimness of out- ' See McCosh, Cognitive Powers, p. 49. LOCALIZATION OF SOUNDS IN SPACE. 131 line of a distant object, tlie retinal elements being bnt feebly excited, e. Diminished size, fcAver of the elements being ex- cited. /. In addition, there are more general considerations which aid our estimation of distance, such as the number of intervening objects, the known size of tl;ie object, and others. But these, with the tv/o preceding, partake more of the na- ture of a conscious judgment. That the muscular movement of the eye is concerned in the estimation of depth, is proved by the fact that when any one of the muscles is destroyed, the localization of objects away from us is mistaken. This is ex- plained by the consideration that the locality which is asso- ciated with a given feeling of movement, is fixed upon whenever that feeling is experienced, uven though the actual movement do not take place. The finer estimation of distance is a matter of cultivation and practice. Indications entirely lost to the ordinary ob- server are unconsciously taken into account by the sailor and artist: such as the length of shadows, the air perspective, and delicate discrimination of colors. All this is clearly a matter of acquired judgment, which may be improved to an endless degree, almost, by the exercise of trained attention and study. In pictorial art, the process is reversed, the ob- ject being to interpret back upon a plane surface those data of the perception of depth which have been before uncon- sciously recognized. So fixed do the associations of distance become that, while our own sense experiences were sufficient to convert our primitive sensations of color into a complex of objects about us, we need a teacher of tlie elements of per- spective to enable us to revert again to the conditions of our original perception. Localization of Sounds in Space. The position of sounding objects in space is roughly indicated by the ear, but this rough localization proceeds upon the pre- vious intuition of objects by touch and sight. It is only after the surrounding world is tolerably familiar and its sounds alread}^ associated with known objects, that the sensations of hearing are definitely placed. This locali- zation by the ear involves distance and direction. The distance of sounding bodies is judged from the intensity of the sound, especially when its normal sound is well known! When the hearing is impaired, sounds are lo- cated farther away. The sense of direction seems to 132 PERCEPTION. arise from several causes, tlie principal of wliicli is the relative strength of the sound in the two ears. The sounding body is located on the side of the ear which re- ceives more sound waves. If a sound be made on the median vertical line through the head — say above — it is not localized, but a slight variation on either side the line is at once detected. Consequently, we locate sounds as right and left, before and behind, much better than up and down. Again, there is a tendency to locate loud sounds in front, from the fact that more sound waves from that direction are collected by the external ear. Delicate sensations of touch and muscular move- ment, also, in the ear, aid us in localizing sounds, though to a much less degree than in the hearing of some ani- mals w^hose ear muscles are largely developed. Feeling of Equilibrium from the Ear.' Recent inves- tigations have shown that the feeling of- equilibrium of the body in space is due to combined muscular and auricular sensations." The feeling of erectness arises from muscular strain in the limbs and trunk. The feel- ing of direction involves also the muscles of the e3'e. Feelings of the rotation and general position of the head in respect to the body, are given by the semicircular canals of the ear. These canals are projected in the three dimensions of space to which they seem to have, respectively', a determinate relation.^ ^ Sec Ferrier's account in Functions of the Brain, 2d ed., cli. iv. i. ^ Delage, Archives de Zool. exper., No. 4, '86, pp. 535-624 (see Amer. Jour, of Psych., No. 1, p. 179). ^ Cf. Elie de Cyou, Comptes Rendus, 1877, and Mind, vol. in, by whom the semicircular canals are considered to be immediate sense- organs for the perception of space. He finds in the eighth pair of cere- bral nerves two distinct sensor courses, the auditor}' nerve and the space nerve. He also shows that there is a connection between the canals and the motor functions of the eye muscles, thus brinsriug into the problem the phenomena of ocular movement, which Delage thinks suf- IDEAL PRODUCT OF LOCALIZATION. 133 Ideal Product of Localization: Idea of Space. The appreliensiou of space as thus treated, is acquired in concrete perception. Space, heretofore, has meant ex- tension, considered as an attribute of objects extended. The finished idea of space, as a void continuum, is derived only by a process of abstraction to be consid- ered later. From the perception of a body extended we pass to the conception of an extension or sj)ace which ihis body fills : we abstract the body and leave the space. The infinite aspect under which both this idea and that of time take form, also comes up for further exposition. § 5. Theories of Space Perception. Two general theories of space perception are held by psychologists, and under them may be classified the various attempts made to explain the origin of this idea. These are the nativist and the empirical theories. Em- piricists hold that presentations of extension (and time) are derived through experience from elements which have not the spacial (and temporal) form. On the other hand, nativists maintain that space and time presenta- tions cannot take their origin in data of consciousness which are simply intensive ; consequently that these presentations are primitive data of knowledge, native, innate. In other words, the empiricist asserts the re- ficient to account for certain rotatory movements of the body without the canals. Cyon advances the theory that the canals have the general function of presiding over the discharge and innervation of the motor ■centres for all the muscles; and of giving us at once an idea of space in three dimensions. " This central organ of the .sense of space presides in the distribution and graduation of the force of innervation commu- nicated to the muscles for all the movements of the globe of the eye, of the head, and of the rest of the body." — Comptes Rendus, 1877, p. 1285. As a philosophical theory of the origin of the perception of space, this view of a special space sense is open to the objections already urged to all strictly empirical theories. See, also, experiments of Brewer, Amer. Jour, of Psych., vol. ii. p. 333. 134 PERCEPTION. ducibilitj of presentations of space and time, and the nativist asserts their irreducibilitv. Further, nativism may be considered as a nativism of process, or a nativism of product. The former is the theory already advocated and has been sufficiently ex- plained: it is held with some differences of detail by Wundt and Lotze. I. Nativism of Product: Kant. According to the latter, the idea of space and time are the necessary products of the mind's activity in sense perception, and the universal forms which it contributes to the intuition of things. Space, therefore, is an ideal innate construction of the mind imposed upon an unknown external content, rather than a synthetic reconstruction by the mind by which objects which exist, become objects perceived, known. In objection to the theory from a psychological stand- point it may be said: a. It does not account for the dif- ference between the extensive and the non-extensive sen- sations. If space is a form of mind in its sense function,, why do not all sensations show this form ? h. The per- ception of sj)ace cannot be placed on the same footing with that of time, since time is the form of all sensation , and higher activity.' c. Again, the idea of space is not given to us as a finished product, but is built up from tentative experiences of objects. It is a combination of empirically derived localities, which owe their position to signs in the objects themselves. It is only as essential data to the notion of space that differentiating local col- oring can be effective. How could objects having no ' The distiaction of Kant, that space is the form of external sense (sight, touch) and time the form of internal sense (consciousness) is not exact. For color, feelings of touch, etc., are just as much internal as any other facts of consciousness. The phrase "external sense" can designate nothing more than the ensemble of the senses by which we perceive the external, and to say that space is the form of the senses by which we perceive space is tautoloicy- THEORIES OF SPACE PERCEPTION. 135 local significance take place in a liomogeneous ideal space ? d. The different behavior of young animals and young children shows their percejjtion of space to be different. Young chickens stand erect, run in a straight line, and thrust their bills skilfully in the direction of their food. Young animals turn at once to the teats of the mother. But the young child goes through a long and painful experience in learning the first conditions of spacial movement and action. II Empiricism. The advocates of the empirical deri- vation of the idea of space rely upon one of two means of accomplishing it: deduction and association.^ 1. Deduction. It is said that the form of space (and time) is deduced consciously or unconsciously from data which have not this form. But this seems, if it be truly deduction, to be impossible on its face. A true deduc- tion of space must necessarily proceed upon data, prem- ises, of space ; but to allow it in the premises is not to deduce it. For example, Herbart deduces space from a series of sen- sations whose order may be reversed. Let a picture be the ex- tended object perceived, having the points a, h, c, d, which are successively taken in by the eye. Now, in the mental construc- tion of the image of this object, those sensations longest in consciousness are least intense ; so in order of intensive repro- duction, the points are presented d, c, h, a. Thus is reached an intensive reversal of an extensive order. All this is true; but the question remains, why is this reversed order projected in space ? A scries of musical notes are reversed in intensity the same way, but they do not assume extensive form. There must be some local coloring in a, b, c, d, in addition to their time order; but to admit this is to assume the thing deduced. In the same way. Mill overlooks the specific character of the notion of extension in reducing it to a feeling of simple suc- cession. ''The idea of space," says he, "is at bottom an idea of time: the notion of extension or distance is that of a series of muscular sensations continued for a longer or shorter time." ' Cf. Rabier, loc. cit. p. 132. 136 PERCEPTION. 2. Association. Tiie case is uo better with association, ias a means of deriving space from unspacial data. Can spacial presentations be constructed from an association of elements foreign to space perception? Not at all; for association lias no transforming power, wliereby a prod- uct is arrived at specifically different from the elements associated. Association can unite what was separated and dissociate what -sras united; but from the nature of mental states, as states and not things, the laws of their .association give no clue to their transformation in terms of extension. Consequently, as says M. Eabier, psychol- ogists who have recourse to association to explain pres- entations of extension, fall into one of two fallacies : either they introduce extension covertly into the associ- ated data, or, preserving the premises free from exten- sion, they bring forth a product which is not extension at all. Either a petit io principii or an ignored io elencM is the result. Bain's view seems to illustrate the first of these fallacies. He derives the notion of space from the association of muscu- lar sensations among themselves and with tactual sensations. '''The prolongation of the muscular contraction," says he, ''indicates the course of the organ through space." Now if the idea of space enters through the intensive feeling of muscular contraction, there is more in our conclusion than in our premises and we have an ignoratio ; if, on the other hand, the sensation is one of movement proper, extension has already entered and we need no association; i\\\&\?, a petitin. This criticism applies to the theory of Bain in all its details, .as to the origin of vague representations of extension, the measure of extension, and direction, all of which he aims to -derive from conscious musculnr sensations and their differ- ences in point of intensity, succession, and rapidity. In all this there is not, in our view, the first beginning of an expla- nation of the origin of the notion of space. We are obliged to fall back upon a power of mind wliereby the data, given in •sensation as affective and intensive, become extended in per- ception. The question has often been asked of empiricists, why it is that the muscular sense alone, and not other senses, as hear- THEORIES OF SPACE PERCEPTION. 137 ing, gives us this idea,. In sounds there are differences of intensity, duration, and rapidity. Feelings of continued or successive resistances are feelings just as feelings of continued and successive sounds are, and, before the association claimed, they are equally wanting in the form of extension. Why then are the muscular sensations alone convertible into extension ? Bain and Spencer cannot answer, as we do, that it is by rea- son of certain characteristics of these sensations upon which the mind's peculiar space perception proceeds. They would then be nativists. They are bound to explain why it is that notes do not form lines nor chords surfaces, while muscular sensations, which are equally intensive affections, do form lines and surfaces. The second of these fallacies is exemplified by the theory of Mr. Mill already spoken of. He starts with succession a matter of time, ends with succession a matter of time, and does not reach space at all. Under the term "synthesis," some empirical thinkers at- tempt to hide the weakness of the case for association. They distinguish a simple mixture from a synthetic combination. Space, say they, is the result of such a synthetic combination of elements to which it is in the first place foreign. But if it be a true synthesis, by its very nature it conceals the proper- ties of the elements combined, and it is impossible to say what mental data are involved. How do we knov/ that the states of consciousness indicated as elements of the presentation of extension, are not simple occasions, antecedent conditions, which in themselves do not suffice for its production, however they may be necessary to it? Any such empirical synthesis is open to the demand that the account of its elements be ex- haustive: to admit any unknown element is to give up the empirical position, for this element may be native. From this point of view, the advocates of synthesis grant to the "nativists of process" all that they ask. They grant that presentations of extension appear suddenly in consciousness, they do not know how; and that these presentations cannot be derived logically from any other states of consciousness. This opens the door for the claim of the nativist, that while these elements are truly concerned in the mental synthesis of space, and while the empiricist's appeal to an unknown combi- nation is justified by our ignorance; yet we may go farther and say that no such intensive elements and no such combinations can be, in themselves, sufficient, without a native reaction of mind by which space is reconstructed. 188 PERCEPTION. § 6. Intuition. The third and last stage in the mental synthesis of the finished perception of the external world may be called Intuition. In the first of the three stages under which we found this process naturally taking place, i.e. Differentiation, we saw the breaking up of the general and vague sensory continuum of the earliest child expe- rience into the difi'erentiated and recognized sensations of the different senses ; in the second, i.e. Localization^ these sensations have taken position in space ; in the third, i.e. Intuition, sensations are gathered together in the permanent units or wholes which we call things in our developed perception. As illustrating the incompleteness of the perceptive process at the stage to which we have now advanced, we may imagine the subject with a given number of well difi'erentiated and localized sensations ; say, a taste, a smell, a touch, and a color. These have no connection among themselves at their first experience, although given the same local and temporal position. There is no reason that they should be thought of together, or that one should suggest the other. That is, there is no reason that the intuition apple should emerge. There is a further process by which this important lack is supplied, and sensations, until now isolated and disconnected, are thrown into permanent comj)lexes or groups. In this, further advance, several necessary steps are apparent. I. Attention. However sensations may be grouped in the passing panorama of diffused consciousness, they have no connection unless their coexistence is attended to. And not only so, but it is doubtful whether simple passive attention would be suflicient for the grouping of sensations in a complex whole. It may at least be safely said, that the arranging and coordinating power of act- ive attention c;reatlv facilitates the earliest intuition of INTUITION. 130 things. It is here that the rehiting or apperceptive func- tion of active attention is most apparent. It will be seen in treating of memory, that the degree and intensity of the power of retaining and reproducing presentations depends upon the degree of attention given to the origi- nal experience. This is especially true of the relations in which these original presentations stand to one an- other. The touch, taste, color, smell, or any two or three of the qualities of the a23ple are experienced, for the first time, in immediate conjunction and, while merely a colligation of sensations, are attended to as such, and their coexistence apprehended. At first the muscular and touch sensations, as localized, precede, and with these the sensations of other senses are observed to be simultaneous. Thus begins the further fact : II. Association: a principle by which presentations once experienced together, tend to come up in memory in the same order of contiguity. By this principle, the renewed experience of one of the former sensations tends to arouse the others with which it was before experi- enced. In the further extension of our experience, ad- ditional sensations are added to the associated complex, as when we learn that an apple before known as spheri- cal and red, is also sweet and fragrant. Like associa- tions in general, this grouping of sensations becomes fixed only by extensive repetition and movement,' and as this repetition and movement conform to or modify the complex, the intuition is confirmed or new products distinguished. Thus the object in perception becomes clearly defined and distinguished from others, and the external world takes on its permanent form, as a whole of various things existing in space relations. An additional fact, important to tlie permanent fixing and discrimination of percepts, is this, that we learn very early ' On the function of movement in defining and differencing things, see Waitz, Lehvbuch d. PsycJiologie, § 48. 140 PERCEPTION. to name objects as we perceive tliem. This is the result of a mental power considered later, and need be noticed here only as a great auxiliary to tlie lasting quality of our sense intuitions. In the ordinary education of children, when their knowledge of language goes ahead of their experience of things, the names are ready beforehand and are aj)plied, under instruction, to objects present, with a number of qualities clearly pointed out. Thus the process of growth in the com- bination of qualities is greatly abbreviated. Teaching by object lessons is therefore justified psychologically as a method, in that it leads the child to attach the right name to the right object, in the first place, and thus to avoid all tentative and mistaken efforts at discrimination. Motor Intuition.' The organized data of muscular movement become for the motor consciousness what the organized sensations of the special senses become for the affective consciousness. Individual motor feelings are integrated in intuitions of external worth. These motor intuitions take the form of ideal coordinations of movement, and become more and more sure and auto- matic as the muscles are exercised in grouj^s after re- j^eated effort. In as far as they are constituted from simple sensations of movement, they are the earliest data for sense intuition in general. But in as far as feelings of effort are also bound up with feelings of movement, the former constitute a new and active meas- ure of our perceptive construction of the external world. The early random movements of the child are thus worked up into the systematic coordinated muscular groups of the adult life, by adaptation to the environ- ment. Ideal Product of Intuition. In the process of combin- ing different sensations into a percept whose meaning for the mind is that of a single thing, a new idea or notion takes its rise. This is the idea of synthetic unity. By syn- thetic unity is meant the unity that stands for itself alone ' Beicegxingsanschauung . Compare Maudsley's discussion, Physiology and Pathology of the Mind, American edition, chap. viii. SENSE PERCEPTION AND THE UNCONSCTO US. 141 and cannot be divided ; yet tlie imitv that lias parts, and results from tlieir synthesis — as the idea of an organ- ism, made up of its various organs. The percept is such a product. The fact of many presentations be- comes the fact of the presentation of the man}*. In the words of Kant : " The conception of combination involves, in addition to the notion of multitudinous elements and their s^-ntheses, the motion of their unity. . . . Combi- nation may be abstractly defined as the idea of the syn- thetic unity of the manifold." ' This is to be distinguished from the idea of general or numerical unity wliich probably rises in consciousness earlier. It is difficult to see liow all feeling of unity and plurality can be absent in the beginning of the differentiation of sensations. It is more difficult as soon as sensations begin to be localized, as are sounds in time and things in space succession. The very discrimination of mental states seems to involve numeri- cal difference. This must precede the idea of synthetic unity, therefore, since the notion of combination includes that of the different units which enter into it. Sense Perception and the Unconscious. In discussing tlie unconscious,^ we have already spoken of the theorists who claim that the fact of a process in perception, of which we are not immediatel}^ aware, is evidence of un- conscious mental activity. If this threefold process takes place, we are told, and we are not aware of it, it must be unconscious. Yet upon looking closely at the process as we have understood it above, this necessity is removed. "We must consider that the growth of percep- tion is coincident with the growth of consciousness itself. However true it is that we know no such process in per- ception now, it is also true that we did know it, in part, when our consciousness was first taking form. The dif- ferentiation of sensations and their recognition as quali- tatively distinct, were perfectly conscious. The young ' Quoted by Morris, Kant, pp. 106-7. ' Chap. IV, § 2. 142 PERCEPTION. child is conscious of tlie sounds and siglits around it, even before it discriminates tliem. In the process of localization in space, the case is different, and upon this great stress is laid.' But here, if we accept the exj^lanation given above, we are not called upon to recognize mental elements at all among the unconscious data of this form. Muscular movement and local signs are physical data, and the synthesis whereby they indicate space position is an immediate act of mind. It might with equal reason be claimed that because the will proceeds upon nervous discharge at the motor centre, a volition to move the arm is a derived and secondary mental fact and rests upon unconscious processes. The fact that the synthesis of these data is mysterious and its exact nature quite unknown, is suffi- cient to forbid a conclusion that it rests upon uncon- scious mental elements. As for localization in time,^ the case is clearer still. Here we have no reason to suppose the unconscious. The two classes of data involved are both j^erfectly con- scious, i.e. intensity of sensation and movements of at- tention. In the final stage, also, intuition, we deal with the earliest forms of child- consciousness, as in diiferentia- tion. Consciousness is itself developing. It is probable that the grouping of sensations and their association in permanent form rests upon conscious experience. This process leaves no trace upon adult consciousness, after the analogy of all such early experience. And after the reasoning power is called into activity, the intuitive syn- thesis is no longer necessary, since by that wonderful capacity of mind to abridge its efforts and conserve its l^roducts, old products are held by a name, and the idea of synthetic unity is ready formed for any combination of external qualities we may meet in nature. 'By Wundt. ' See Chap. X. SELF-CONSCIOUSNESS: IDEA OF SELF. 143 Deceptions of Sense Perception. Errors arise in the process of synthetic perception from the fact that we are no longer conscious of the steps in the process. We fail in our estimate of distance by the eye, of direction by the ear, of time, past and future. We are subject to certain permanent optical illusions. These and all other mistakes of the senses are explained as being fallacious inferences from data at one time conscious and truthful. These errors cannot be shown to extend to sensation it- self. A sensation must, by definition, be what it is felt to be. For the same reason, error cannot attach to the presentative element in our first experiences. This will be further treated in the chapter on Illusions.' § 7. EeFLECTIOX or SeLF-CON"SCIOUS]S'ESS.' The highest form of consciousness has been seen to 1)6 se?/*-consciousness. In self-consciousness there is a turning in of the experience upon the self. This involves the establishment of the relation of subject and object which is the fundamental fact in perception, and the re- turn of the mind to itself as its own object. By the result of reflection is meant, therefore, the knowledge which the mind has of its own operations, recognized as its own. It is an advance on the simple awareness of consciousness, in which there is no reference to self as different from its object. In reflection, this reference has distinct place, and the self is discovered through the act of attentive in- spection, as having and exercising the characteristics of mind. The notion of self, lilie other notions, is a grad- ual growth. The vague feeling of the ego which the first affective experiences afford, is defined and enriched by added marks, such as efiiciency, identit}-, and perma- nence. Especially as cause is the self realized early, in connection with muscular feeling and will. ' Chap. XIII. « Cf. Chap. I, § 2. 144 PERCEPTION. Ideal Product of Eeflection : Idea of Self. Tliro ugli re- flection, therefore, the idea of self is attained and as- sumes its im23ortant place in the mental -svorld. Round the self as a centre the intellectual life plajs. To it all possible forms of experience are referred. It brings co- herence into the circuit of consciousness, by giving it a centre of reference and a circumference of limitation to the individual. On perception., consult: in general, McCosh, Cog. Poivers, bk. 1, eh. I; Wundt, Phys. Psych., ch. xi-xiv; Carpenter, Ment. Phys., ch. v; George, Psycliologie, p. 77 ; Porter, Hum. Intel., pp. 158-221; Ladd, Phys. Psych., pp. 382-467 ; Wundt, llieorie d. Sinneswahrnehmung , pp. 376-445 ; Waitz, Lehrhuch, §§ 20-27, and Grundlegung der Psychol., pp. 92-100; Fortlage, System der Psychologie, § 31 ; Lau- rie, Metaphysica, pt. 1; Spencer, Psychol., n. pp. 131-256 ; Sergi, Teoria fisiologica del percezione ; Loewy, Die Vorstellung des Binges; Binet, La Perception exterieure; Uphues, Wahrnehmung und Empflndung ; Ueberweg, Logic, pt. 1; (History of) Bailey, Letters on Philos. of Hum. Mind, 13-20; Sergi, Psychologie Physiologique, bk. 2, ch. iv-vi ; Ward. Encyc. Britann., art. Psychology; Hamilton, Metaphysics, Lect. XXI-XXVI. Besides, general treatment is to be found in all the works upon psychology, as Sully, Outlines; Rabier, Psychologie ; Spencer, in loc. On space-perception : Fortlage, Beitrdge ztir Psychologie, pp. 342-281 ; Volkmann, Lehrhuch d. Psychol., § 18 ; Ribot, German Psychol., ch. iv; Herbart, Lehrhuch der Psychol., §§ 167-178; Stumpf, Psychologischer JJrsprung der RaumvorsteUnng ; Spencer, Psychol- ogy, n. pp. 178-216 ; Montgomery, Mind, x. pp. 227, 377, and 512 ; Hall, Mind, in. p. 433 ; Sully, Mind, ni. pp. 1 and 167; Sergi, Psychologie Physiologique, bk. 2, ch. vii and x ; (History) Porter, Hum. Intellect, ch. ix ; Binet, Revue Philosophique, xxi. p. 113 ; Berkeley, Theory of Vision; James, Mind, 1888; Ward, loc. cit.; Lipps, Grundthatsachen des Seelenlehens, ch. xxi-xxv, and Psycholo- gische Studien, i; Lotze, Metaphysic, bk. 2, ch. i, and bk. 3, ch. iv. Further Problems for Study : Subject and object in perception ; Validity of the perception of the external world ; Philosophical bearings of the doctrine of perception ; History of theories of perception. REPRESENTATION. MEMORY. CHAPTER IX. IlETE:N^TIO:fT AKD EEPRODUCTIOIN". The data of knowledge, as they are afforded by the acquisitive function of mind, have been thus far enu- merated and distinguished. This expression, data of knowledge, implies that these acquisitions remain at the disposal of other mental functions longer than the mere instant of their first experience ; otherwise, they would not be the materials of knowledge. Our states of consciousness, as a general fact, may be spontaneously revived. The original states of consciousness are desig- nated Presentations, or primary states ; and the corre- sponding revived states, to which they give rise, Repre- sentations, or secondary states. § 1. General Nature of Memory. The capacity to be revived on suitable conditions ex- tends to all states of consciousness. This revival is most vivid and facile for sensations of sight, touch, and sound ; from the fact already noticed that these sensa- tions are most presentative, having the forms of sj^ace and time. Objects seen are readily pictured when the eyes are closed, and sounds of tunes, and more espe- cially of words, are reproduced with great ease. In read- ing a page, we recall the sounds of the spoken words in- voluntarily ; and, if it be a page of poetry, the rhythm and rhyme are caught by the quick revival of the words 145 146 BETENTION AND REPRODUCTION. and measures in succession. Other sensations, as tastes and odors, are also cajoable of reproduction. The fact that we distinguish and classify them is sufficient proof of this. Their reproduction is more obscure from the fact that, being more affective, they cannot be pictured under the presentative forms of time and space. But that these forms, and consequently memory pictures in general, are not essential to memory, is seen in the fact that pains and pleasures, and the emotions, which are purely affective states, are remembered with great dis- tinctness ; these states afford no data for our picturing faculty. According to Epicurus, the memory of past jjleasure and the imagination of future pleasure are the 23rincipal source of our happiness. Sympathy depends upon the revival of our own j^ains and pleasures ; for we cannot sympathize strongly in cases which our own ex- 2)erience does not cover. And finally, the acts of will are present in memory, giving, according to their nature, moral satisfaction or regret. Strictly speaking, a distinction is to bo drawn between states which are revived after having once disappeared from consciousness, and those which per.'^ist in consciousness a short period after the external stimulus has ceased to act. The latter is a mental after-image, somewhat like the physi- cal after-image on the retina, already mentioned. Every per- cept clearly distinguished leaves its outline in consciousness for a very small period, and then fades rapidly away. In the case of a rapid succession of presentations, each percept occu- pies less time than the unit of duration,' so there is a coexist- ence of presentations and not a revival. This is the case, prob- ably, with written and spoken words, tunes, rapid rhythm. Nature of Bevived States. As to the nature of the states brought up in memory, two general theories are held. On the one hand, it is maintained that there is a specific difference between presentations and theii; revived images ; a difference of nature. Secondary ' See p. 185. PEESEXTATION AND REPRESENTATION. 147 states resemble the primary, it is said, as a portrait re- sembles the original ; but there is an absolute distinction in their nature.' In opposition to this view, others hold that between primary and secondary states, there is only a difference of degree. They are truly Presentation and i^epresentation ; their nature is the same.' Proof that Presentation and Representation differ only in Degree or Intensity. Several kinds of evidence may be adduced in support of the second of these theories. I. From Consciousness. We are aware in conscious- ness of no peculiar marks of revived states by which to distinguish them from percepts, except that they are prevailingly of less intensity. In the conscious repro- duction, the conditions of the presentation are vaguely reproduced. The representation of a name, sound, the tic-tac of the pendulum, is referred to the ear. The im- age of an extended object is formed as extended in the field of vision. If we try to recall the taste of an orange, we seem to have a kind of after-taste on the tongue. In recalling emotions, the general conditions of our first ex- perience of it are found with it in memory by the law of association. In the case of voluntary reproduction, it is true, there is the addition of an exercise of will," which is of great importance in affording us a means of distin- guishing between the percept and its image ; but this is not necessary to the reproduction more than to the orig- inal perception, since most of our memory pictures arise involuntarily. II. Presentations and Representations have the same Physical Antecedents and Effects. The physical antece- dents of both primary and secondary mental states are ' So Reid and Caidaillac. ^ So Hume, most of the English school, and the physiological psy- chologists. Cf. Kabier, loe. cit. pp. 152-157. 2 Fichte makes the feeling of freedom essential to all reproduction. 148 RETENTION AND EEPBODUCTION, spoken of later under tlie physical conditions of memory. It is sufficient to say, liere, tliat tlie immediate physical antecedents, the brain processes, are the same in both cases. The remote antecedents of the percept — presence of an object, and stimulus of the sense — are wanting in the case of the revived image ; but it is the immediate antecedent upon which the representation depends. The physical consequences or elfects are also the same. Miiller says, that the simple idea of a nauseous taste is sometimes sufficient to produce sickness, the natural effect of the real sensation. The visual picture of a person who has once provoked our anger serves to produce it again with the same physical expression. Intense mental picturing of a primary color may so ex- haust the retinal elements, that the complementary color is seen when the eyes are opened." It is hard to think upon an energetic action without imitating it, just as in the original attention to the performance of it by others, we had such a bodily tendency ; and to have a word in mind is usually to form it "svith the organs of speech. Further than this, the ps3'chological antecedents and con- sequents are ahnost identical in the two cases. There is this difference between the train of presentations and that of rep- resentations, that the latter is accompanied by a feeling of familiarity and anticipation. But it is doubtful whether this feeling is present at the first reproduction, since it involves a measure of previous knowledge which can only be representa- tive. This feeling is present in the perception, also, when by repetition an element of representation is involved in it. The voluntary character of certain reproductions, which seems to make them peculiar as to their antecedents, has its counterpart in certain voluntary efforts of perception ; as when we explore an unknown scene with the eye or feel over an unknown sur- face. Further, as to the consequents — the simple thought of great cold makes one shiver. The thought of the drawing of a sharp knife over glass sets one's teeth on edge, as Darwin says. Any one who has attended a clinical operation knows how acute the sensations of cutting and drawing are at first. ' Lewes, Problems, 3d series, p. 448. PRESENTATION AND BEPRESENTATION 149 The effects of attention, also, are the same upon the image as upon the first sensation. III. Freqiient Confusion hetween Presentation and Bep- resentation. The strongest, indeed the decisive, proof that psychologically these two classes of states are really one is this : we frequently mistake one for the other. " The proof," said Keid, " that there is an essential differ- ence of nature between these states is that we never confound a sensation, however feeble, with an image, or the contrary." This is simply an error of observation. We do often confound them, and several different cases of this confusion may be j)ointed out. 1. Wlien the intensity of the image is very great. This is the case in hallucinations and insanity. " Patients continually hear voices speaking to them, or about them, rephing to their most secret thoughts, suggesting to them profane and obscene ideas, and advising and threat- ening them."' In these cases, abnormal brain action gives the image the verisimilitude of a sensation and the distinction is completely lost. The same result may arise in normal life from simple force of imagination. Newton could bring before him, when in the dark, an image of the sun, with all the characteristics of reality, and Goethe could evoke an image and cause it to pass through a series of transformations." Further, there are cases of regular mistake in our perceptions, in which an image passes for the real object. In reading rapidly we do not see all the letters individ- uall}^, but pass over them with a supply of appropriate images. It is probable that we see the first letters of the words and the last, slurring over the middle charac- ters and suppljang them from our knowledge and from the connection. Yet we think that each letter has been seen in order. The blind spot in the field of vision is ' Maudsley, loc. cit. ^ Cf. T