HatE GJnUcgc of Agttculturc At QJocnell UniueraitH atljata, N. 1- Cornell University Library BF 131.T61 A text-book of psychology. 3 1924 014 474 328 The original of tliis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924014474328 A T1XT-B©®K ©F PSYCHOLOGY THE MACMILLAN COMPANY- - NEW YORK • BOSTON - CHICAGO ATLANTA • SAN FKANCISCO MACMILLAN & CO , Limited LONDON • BOMBAY • CALCUTTA ' MELBOURNE THE MACMILLAN CO. OF CANADA, Ltd. TORONTO A TEXT-BOOK OF PSYCHOLOGY BY EDWARD BRADFORD TITCHENER PART II WeiD gorft THE MACMILLAN COMPANY 1910 All rights reserved Copyright, 1896, 1897, 1899, By the MACMILLAN COMPANY. Set up and elcctrotyped. Published July, i8g6. Reprinted March, November, 1897; September, i8g8. Revised and enlarged edition printed October, 1899; October, igoo; October, igoi; January, 1905; March, 1906; April, October, 1907; March, 1908, Russian translation, 1898. Italian translation, 1902. Revised edition under new title Copyright, 1909, 1910, By the MACMILLAN COMPANY. Set up and electrotyped. Published June, igog. Reprinted October, 1909. Enlarged edition printed September, igio. German translation, igio. J. S. Gushing Co. — Berwick & Smith Co. Norwood, Mass., U.S.A. CONTENTS PERCEPTION Spatial Perceptions PAGE § 85. The Sensory Attribute of Extent 303 § 86. The Third Dimension _ ,06 §87. The Stereoscope 3,6 '§88. The Perception of Space : Locality 321 § 89. The Perception of Space': Magnitude 326 § 90. Secondary Spatial Perceptions 330 § gi. Illusory Spatial Perceptions 332 § 92. Theories of Space Perception . 33c References for Further Reading 338 Temporal Perceptions § 93. The Sensory Attribute of Duration ...... 340 § 94. The Perception of Rhythm 344 §95. Theories of Time Perception ....... 346 References for Further Reading 347 Qualitative Perceptions § 96. Qualitative Perceptions 349 § 97. Tonal Fusion 351 § 98. Theories of Qualitative Perception 352 References for Further Reading 355 Composite Perceptions § 99. Simple and Composite Perceptions ...... 357 \ 100. The Perception of Movement 357 } 101. The Perception of Melody 360 References for Further Reading 363 VI Contents The Psychology of Peeception PAGE § 102. Pure and Mixed Perceptions 365 § 103. Meaning 367 § 104. The Form of Combination ........ 371 References for Further Reading 373 ASSOCIATION § 105. The Doctrine of Association 374 § 106. The Idea 376 § 107. The Law of Association ........ 378 § 108. The Experimental Study of Association ..... 380 § 109. Results : The Conditions of Impression ..... 382 § 1 10. Results : The Conditions of Associative Tendency . . . 384" § III. The Associative Consciousness ....... 389 References for Further Reading 395 MEMORY AND IMAGINATION § 112. Retention: The Course of the Image §113. Retention; The Process of Dissociation § 114. Retention: Individual Differences § 115. The Recognitive Consciousness . §116. Recognition and Direct Apprehension § 117. The Memory Consciousness § 118. The Memory Image and the Image of Imagination § 119. The Imaginative Consciousness . § 120. Illusions of Recognition and Memory. References for Further Reading . 396 401 403 407 410 413 416 421 424 426 ACTION § 121. The Reaction Experiment 428 §122. The Analysis of the Simple Reaction 432 § 123. Compound Reactions ..y, 447 § 124. Action § 125. The Genesis of Action .^n §126, The Classification of Action ^cg Contents vii PAGE § 127. Will 466 References for Further Reading • 469 EMOTION § 128. The Nature of Emotion 471 § 129. The ' James-Lange Theory ' of Emotion ..... 474 §130. The ' James-Lange Theory ' • Criticism and Modification . . 476 § 131. The Organic Reaction as Constitutive of Emotion . . . 481 § 132. The Organic Reaction as Expressive of Emotion . . . 484 § 133. The Forms of Emotion 489 § 134. Emotive Memory ......... 493 § 135. Mood, Passion and Temperament ...... 497 § 136. The Nature of Sentiment 498 § 137. The P'orms of Sentiment ........ 500 References for Further Reading 503 THOUGHT §138. The Nature of Conscious Attitude 505 §139. The Alleged Elementary Process of Thought .... 508 §140. The Alleged Elementary Process of Relation . . . .512 § 141. The Analysis of Conscious Attitude . . . . . • 5'S § 142. Language 521 § 143. The Abstract Idea 525 § 144. Generalisation and Abstraction ....... 529 § 145. Comparison and Discrimination 532 § 146. Expectation, Practice, Habitualtion, Fatigue .... 537 § 147. Judgment 540 § 148. The Self 544 References for Further Reading 547 CONCLUSION § 149. The Status of Psychology ........ 550 References for Further Reading 552 Index of Names ........... 553 Index of Subjects ........... 555 INDEX OF FIGURES FIGURE PAGE 45. Model of the Horopter 310 46. Stereoscopic Slide . . . . . . . . . .311 47. Stereoscopic Slide . . . . . . . . . .312 48. Wheatst one's Stereoscope 317 49. Plan of Wheatstone's Stereoscope . . . . . . • 3'7 50. Plan of Brewster's Stereoscope 318 51. Demonstrational Stereoscope ..... -3^9 52. Stereoscopic Slide . 321 53. Plan of Binocular Colour Mixer (Hering) ..... 321 54. Diagram Illustrating Visual Acuity (Hering) 324 55. Blind Spot 328 56. The Muller-Lyer Illusion: Ebbinghaus' Swallow Figure . . . 333 57. Mach's Book Figure ......... 334 58. Illusion of Movement (Bourdon) ....... 359 59. Artificial Waterfall (James) ........ 359 60. Memory Apparatus (Ranschburg) 381 61. Field of Telescope 429 62. Hipp's Chronoscope ......... 430 63. Wundt's Sound Hammer . . . . . . . -431 64. Telegraph Reaction Key 431 65. Figures for Abstraction of the Like (Griinbaum) .... 531 PERCEPTION SPATIAL PERCEPTIONS § 85. The Sensory Attribute of Extent. — We said in § 12 that visual and cutaneous sensations are spread out, areally, into length and breadth; they appear as spatial extents. This elementary character of outspread or expanse is the foundation upon which all the forms of spatial conscious- ness, delicate and refined as they are, have been built up. To realise it, we must go behind our adult modes of space- perception. The words ' area ' and ' extent ' naturally sug- gest to us some well-known surface, field or walVor table ; and the surface has a definite form, a definite size, a definite distance, a definite position within the spatial field ; its per- ception implies a whole space-psychology. We are now dealing, however, with extent of a more primitive kind : an extent that is merely expanse, without particular form, without recognised magnitude, without relation to other extents, neither near nor far, — an extent that is present as extended, and that is all. We can, perhaps, get the best idea of it by closing the eyes and observing the dark field : here is an outspread of black, or of dark red, but it is an outspread with no definite size or shape, and it lies neither on the eyeballs nor out in space. We get an ap- proximation to it when we open the eyes in a completely dark room, or face a bank of thick fog, or gaze through half-shut lids at the blue sky, though in these cases the effort to abstract from what we know of space is greater and oftentimes less successful. 303 304 spatial Perceptions We may imagine, then, that the untrained eye sees the landscape as we ourselves see the field of the closed eyes. But the landscape is not uniform : there is usually a marked difference between what is above and what is below the horizon ; and the lower portion is variegated, made up of patches of colour which, at least in many cases, contrast with one another. The landscape is also, to a certain de- gree, in movement : clouds travel across the sky, and living creatures move about beneath the sky. Visual expanse, as the world of spatial stimuli is constituted, thus contains within itself the cues to localisation ; colours are not only spread out, but they are also spread out here and there, spread out now here and now there. The perceptions of form and magnitude, and the perception of place or posi- tion, have their root in one and the same datum of extent. Psychology has, unfortunately, been occupied rather with theo- ries of the origin and growth of space-perception than with the introspective study of psychological space itself. And we find, accordingly, the most radical disagreement among authorities. At the one extreme stand the statements that a certain roominess or volume " is discernible in each and every sensation, though more developed in some than in others,'" and that " the accompaniment of a local sign or local characteristic is common to all sensa- tions " ; ^ at the other, the statement that spatiality cannot be " an original attribute of the elements themselves, in any such way as intensity and quality of sensations are original attributes " ; space implies the " arrangement of sensations," so that a sensa- tion with a spatial attribute is " psychologically impossible." ^ The position taken in the text lies between these extremes. It grants ' W. James, Principles of Psychology, ii., iSgo, 135. We recur to the question of the third dimension in § 86 ; cf. supra, pp. 51, 94 f. 2 M. von Frey, Die Gefuhle und ihr Verh'dltnis zu den Empfindungen, 1894, 12. ^ W. Wundt, Outlines 0/ Psychology, 1907, 114. § 85. The Sensory Attribute of Extent 305 to some sensations an original character of spatial outspread, and it makes localisation of these sensations a necessary consequence of qualitative differences within the total bidimensional field. What sensations, then, have the attribute of extent ? From his own introspection, the author would reply, with- out hesitation, that visual sensations and sensations off cutaneous pressure are spatial, and that sensations of hear- ing and of smell are spaceless. He inclines to believe, further, that the other cutaneous sensations (warmth, cold, pain), the organic pressures and pains, and all the sen- sations of the kinaesthetic senses are endowed with the spatial attribute, although they play parts of very varying importance in space-perception. Experiments on this mat- ter are sorely needed; in particular, it seems impossible to say, from unaided observation, whether the taste-quali- ties are extended or whether their spatial appearance is due to concomitant pressure. A psychological iield of space, a varied mental expanse that compels localisation, is furnished primarily by eye and skin (§§ 39, 50), the two organs whose physical extent lies open to the simultaneous operation of a number of spatial stimuli. How it comes about that the sensations from these sensitive surfaces are ordered and arranged in cor- respondence with their external stimuli, we do not know. The suggestion has been made that the arrangement is, in the last resort, a matter of habit: like impressions usually come together and are thus approximated in per- ception; unlike impressions usually come at a distance from one another and are thus separated in perception. Not only, that is, do qualitative differences within the total field give the general cue to localisation, but the run- ning together of like qualities and the holding apart of 3o6 Spatial Perceptions diverse qualities is also, in itself, localisation of a primitive and undeveloped sort. However this may be, the original psychological fields are those of sight and pressure. The visual field is the more homogeneous ; indeed, it has been doubted whether the skin ever supplies a single field, — whether it does not rather give a number of heterogeneous, partial, though partially overlapping fields. Yet if you ob- serve yourself, not too analytically, as you lie comfortably in bed, breathing easily and free from organic disturbance, you may get the impression of a flattened, bidimensional field of pressure, astonishingly indefinite in form and size, but still unitary and single.-' § %6. The Third Dimension. — How, now, do we acquire the perception of depth, of distance away from us, of a third spatial dimension } This question must be asked and answered separately for the two great groups of spatial sensations, the cutaneous and the visual. (i) Tactual Space. — -In its first form, then, our question runs : Could an organism, of like origin and descent with man, but lacking eyes, perceive all three of the dimensions of space } And the answer seems to be that it could : primarily, because the skin can move, in all three objective dimensions, both upon external objects and upon itself. The blind organism of which we are speaking is, by ^ Stumpf raises the question ( Ueber den psychologischen Ursprung der Raumvorstellung, 1873, 283) whether an observer who is entirely naive in matters of space-perception — as he puts it, a new-born baby — would per- ceive the pressure of a finger run round his body as a straight line or as a ring. Stumpf thinks that he would perceive it as a ring of pressure in three dimen- sions ; Ebbinghaus ( Grundzuge der Psychologie, i., 1905, 453) that he would get a large ring in two dimensions. The author, in the light of his own ex- periences of an unitary field of pressure, is disposed to believe that the per- ception would be that of two closely apposed lines (possibly fusing at their extremities), or perhaps of a single broad line, traversed in opposite directions. § 86. The Third Dimension 307 hypothesis, a moving organism. Hence the bidimensional field of pressure, which forms its stationary equipment of spatial consciousness, will be transformed into a bidimen- sional field of active touch ; some preferred part of the skin — hand, finger-tips — will be used for the exploration of external objects ; and as, in all such movement, the cutaneous impression is connected with complexes of artic- ular sensations, the right-left and up-down dimensions will be reduced in conciousness to a common spatial denomina- tor, and will be represented in terms of the sensations aroused by movement. But the organism has freedom of movement in the third or back-forth dimension as well ; so that it gains a third set of experiences, of the same general kind as the other two, and yet distinguishable from them ; it learns to perceive depth or distance away. The shift of spatial emphasis from skin to joint, from cutaneous to articular pressure, would hardly be possible unless, as we suppose, the articular sensations are them- selves spatial in character. The general transition, from bidimensional to tridimensional space, must be favoured by the organism's ability to move and fold the skin upon itself : arms and legs may be crossed ; the hand may be passed around as well as across the head or leg or arm ; or the one hand may explore, in any direction, an object held by the other hand against the T5ody. Moreover, the total movements of the organism, movements of locomotion, involve the third dimension of objective space ; and their conscious representation may be derived, not only from the skin and the complex of joint, tendon, and muscle, but also from the kinaesthetic organs of the inner ear. We have spoken as if the three dimensions of space were, in the world of stimuli, sharply distinct. In reality, they are conventional. 3o8 Spatial Perceptions It is possible to draw, through a given point, only three straight lines that lie at right angles to one another ; and it has proved convenient to work out the science of geometry on the basis of this threefold system of coordinates. In the same way, it is con- venient, when we are dealing with space-perception, to think of the organism as set in a space of three dimensions ; and it is natural to consider two of these dimensions, the vertical and the horizontal ■(up-down and right-left), as lying in a frontal plane, and the third, the dimension of distance (back- forth), as lying in a sagittal plane. But the organism itself need know nothing of geometry ; in per- ceiving the third dimension, it simply perceives objects as near or remote. And it must be remembered that the dimensions change, psychologically, with every change of front executed by the organ- ism : turn to your left, and what was length becomes distance ; lie on your back, and what was height becomes distance. This constant interchange of objective dimensions has undoubtedly helped towards the perception of tridimensional space. I At any rate, our view is that this perception of a third dimension [is due to analogy. The two original dimensions of cutaneous I space are translated into characteristic complexes of articular sen- sations ; and a third characteristic complex of articular sensations gives rise — by help of the skin's movement upon itself — to a third perceived dimension. It is in some such way that the con- genitally blind achieve their direct perception of a tridimen- sional space (§ 90). They are, however, at a disadvantage as compared with our imaginary organism ; for the central nervous mechanism which in man subserves space-perception is essentially a visual mechanism ; sight-space dominates touch-space ; and the human being who is deprived of sight is therefore deprived of much more than his eyes ; he loses also no small portion of his brain. (2) Visual Space. — If you fix your eyes steadily upon some object in the field of vision, — a tree, let tis say, seen through the open door, — the surrounding objects appear in their proper shapes and places ; the space-values of the field are entirely normal. But if, now, you hold up a pen- § 86. The Third Dimension 309 cil, at arm's length, between the eyes and the point of fixa- tion, you find that it doubles, that you see two pencils. And if, after this experience, you consider the field of vision somewhat more carefully, you will find that it shows a good deal of doubling : the tip of the cigar in your mouth splits into two, the edge of the open door wavers into two, the ropes of the swing, the telegraph pole, the stem of an- other, nearer tree, are all doubled. So long, that is, as the eyes are at rest, only certain objects in the field are seen single ; the rest are seen double.^ The images of the former fall upon what are called corresponding retinal points ; those of the latter upon non-corresponding or dis- parate points. Think of the two retinas as slipped, the one over the other, and as held together by a pin driven through the superimposed foveas (p. 88). The two pin-holes then represent corresponding points, the retinal points stimulated by the point in objective space which the eyes, at any given moment, are fixating. Let other pins be driven, vertically, through the two retinas, at any points round about the fovea : in the rough, every pair of pinholes will repre- sent a pair of corresponding points. Now it is clear, if you work the matter out by help of diagrams, that, when the eyes are in a certain fixed position, only a certain number of the points in objective space can be imaged upon corresponding retinal points. The sum-total of these, singly seen and correspond- ingly imaged, objective points is called the horopter. If, for instance, the eyes are directed straight forward to the horizon, the 1 Our habitual disregard of double images is one of the curiosities of binocu- lar vision. It is due in part to the fact that the eyes are in constant movement, so that the various objects in the field are successively fixated ; in part to the indefiniteness of indirect vision (p. 83) ; in part to the suppression of the one or the other image by retinal rivalry (p. 320). Apart, however, from these peripheral factors, it is due, perhaps mainly, to cortical set or adjustment ; we mean, expect, are disposed to see singly things that are objectively single. Cf. pp. 274 f., 464. 3IO Spatial Perceptions horopter may be a plane surface which is practically identical with the surface of the ground upon which the observer stands ; if they are directed upon a point at finite distance in the median plane, it may consist, in theoretical construction, of a horizontal circle which passes through the two eyes, and of a vertical straight line which lies in the median plane and passes through the fixation- point. Suppose, now, that the images of some object in external space fall upon retinal points that are al- most, but not quite, in cor- respondence. The object is seen as single; for the corresponding points are not points in the mathe- matical sense ; a point on the one retina corresponds to a small area on the other. Suppose, again, that the images fall on retinal points that are just a little further removed from correspon- dence. The object is still seen as single ; but it is now seen as extending in the third dimension. That is to say, tridimensional vision, the vision of the object as solid, is a sort of halfway house between single and double vision ; to see a thino- solid is a compromise between seeing it as spatialljr one and seeing it as spatially two. But why should this combination of disparate retinal images take place at all.' Why should not disparity of Fig. 45. Horopter Model, showing the horopter as a horizontal circle and a vertical through the fixation-point. § 86. The Third Dimension 311 images mean, at once and always, that we see the object double ? These are difficult questions ; and we can no more answer them, in any ultimate sense, than we can say, for instance, why light of a certain wave-length is seen as red and not as blue. But we can at all events give a prox- imate answer; we can show under what conditions the combination of the disparate images is effected. Human vision is binocular vision ; the two eyes work together as a single organ. Now the two eyes are like two separate observers, who view the objects in the spatial field from somewhat different standpoints ; so that, within certain limits of distance, the one eye sees a given object some- what differently from the other eye (binocular parallax). There can be no cooperation between them unless their separate views are reconciled and combined; and recon- ciliation is, consists in, tridimensional vision. Draw upon a piece of transparent celluloid the two pairs of vertical lines shown in Fig. 46. Let the distance between the left-hand members of the pairs be 64 mm. ; this is the average interocular distance, or distance from centre to centre of the pupils when the eyes are directed straight forward to the horizon.^ Look steadily at some distant point, and bring up the transparent slide before the eyes, in such a way that the mid- dle points of the left-hand lines fall upon the foveas. These two lines are then imaged upon corresponding points, and are seen as one line. The right- hand lines are imaged upon disparate points ; they are, however, 1 It would, perhaps, be better to say the ' conventional ' than the ' aver- age ' interocular distance, since a distance of 64 mm., though commonly given as the average, is probably somewhat too high (Nagel's Handbuch d. Physiol,, iii., 1905, 292). It is best of all to make the measurement afresh in every in- dividual case (Titchener, Exper, Psychol., I., ii., 1901, 245), 312 spatial Perceptions seen as a single line, standing nearer to you than the other. The combination of disparate images gives the perception of depth. — Now, if you hold up two pencils before the eyes, that in the left hand at arm's length, that in the right a little to the right of the other, and a little nearer ; and if you observe the pair of pencils first with the left and then with the right eye alone, you will find that the left-eye view is represented by the left-hand pair of lines in the figure and the right-eye view by the right-hand pair (binoc- ular parallax) . Draw upon another slide the pair of lines shown in Fig. 47. Look at a distant point, and bring up the slide in such a way that the middle points of the two lines are imaged on the foveas. You see a single line, the lower half of which stretches away, while the upper half inclines towards you. Set up a pencil in this position, and note the images formed in the two eyes. Disparity of retinal images thus accounts for the fact that an object in external space is seen as solid. But the object is also seen as distant from oneself, as lying so many metres away : the point fixated is localised in the third Fig. 47. dimension, just as definitely as the points imaged on disparate retinal areas. How do we localise the fixation-point ? It is possible, of course, that we localise it, too, in terms of retinal disparity. What is now the point of fixation, imaged on corresponding retinal points, has been in the past, and will be in the future, a point that is imaged on disparate retinal points : that is to say, it has been and will be localised, by retinal disparity, in relation to other fixation- points. In time, then, every point in objective space will acquire what we may call a relative position in visual space ; and it is a well-known law of psychology that the frequent occurrence of a relative character tends to transform it, for § 86. The Third Dimension 313 perception, into an absolute character; we speak in absolute terms of a heavy child, a light travelling bag, a strong voice, a good light, without any conscious reference or comparison. The transformation might be greatly assisted, in the case of visual space-perception, by associations derived from tactual space : what we can easily reach would be seen as absolutely near, and so on. Or again, it is possible that we localise the fixation-point by the help of secondary criteria. On the whole, however, it seems probable that absolute localisation is effected by way of muscular sensa- tions, the sensations aroused by movements of accommoda- tion and convergence. The indirect or secondary aids to localisation in depth may be summed up as follows : linear perspective, the course of contour lines in the field of vision ; aerial perspectivej relative clearness of outline and distinctness of hue ; the distribution of light and shade ; interposition, the partial covering of far by nearer objects ; apparent magnitude, — a criterion that is especially valuable in the case of familiar objects ; movement of objects in the field of vision ; and movement of our own head or body : if we fixate a near object, and move the head to one side, distant objects show a movement in the same direction ; if we fixate a far object, and move the head as before, nearer objects show a movement in the opposite direction. No doubt all of these aids have had their share in the formation of our visual space-perceptions ; but it is questionable whether any^ one of them is essential. A like question may be raised with regard to eye-movement : it is, in fact, a matter of keen controversy whether the movements of accommodation and convergence are constitutive factors in space-perception, or whether they are, like the movements of head and body, of merely secondary importance, — e.g., as aids to fixation. On the physiological side we have the fact that the two eyes form a single motor organ ; they move together, automatically, under all the conditions of a possible fixation. If the fixation-point is very 314 spatial Perceptions remote, and lies in the median plane, the lines of regard are parallel ; and they remain thus parallel for remote fixation at any part of the field. If the fixation-point lies nearer, in the median plane, the lines of regard become symmetrically convergent : the eyes, which before were directed straight forward at the horizon, turn inward through equal angles. If the new fixation-point does not lie in the median plane, the lines of regard become asymmetrically convergent; in this case, either the two eyes turn inward, through unequal angles, or the one eye turns in while the other, through a smaller angle, turns out. These two types of convergence are maintained, again, for the fixation of points at any part — up, down, right, left — of the field of vision. In short, wherever the eyes can act together, for purposes of binocular vision, they do act together ; and the one thing that they cannot do is to act separately against binocular vision ; it is impossible, with normal eyes, for the lines of regard to diverge. On the psychological side we have a long series of experimental studies, whose results are not easily harmonised. Psychological opinion is, in the main, unfavourable to the connection of the depth- perception with sensations of eye-movement ; and it must be granted that our discrimination of distance is far more delicate than we should expect it to be, were it mediated solely by muscular sensa- tions. Nevertheless, it seems certain that these sensations can furnish the data for localisation. Recent experiments, carried out with all precautions, lead to the conclusion that in monocular vision the sensations of accommodation, and in binocular vision the sensations of convergence, give fairly accurate cues to the position of objects in external space. The sensations are not always discoverable by introspection ; the perception of distance may come to conscious- ness directly. This, however, is not surprising ; space is so familiar to us, and the cortical set or adjustment for the perception of space must be so entirely habitual, that the immediacy of the spatial attitude is only natural; the surprising thing is, rather, that the sensations in many cases are discoverable, that the peripheral cues do persist in consciousness. At the same time it must be re- membered that sensations of movement, in vision as in touch, are only secondarily, by analogy, the source of our perception of the § 86. The Third Dimension 315 third dimension ; they are, as we have put it, cues to this perception. They may get their spatial significance either from the relative depth-perception due to disparity of retinal images (if that is re- garded as primary), or by a more direct association with the tridi- mensional space of touch. There is, as we have intimated above, a monocular perception of depth. One-eyed persons have no difficulty in finding their way about ; and we ourselves, if we close one eye, suffer from no illusion as to the soHdity of the objects around us. In all such cases, the observer can change his position with regard to sur- rounding objects ; the objects themselves may change their positions, with regard to him and to one another; and various other secondary criteria of distance are still available. As direct cues to the perception of depth there are, first, the sensations of accommodation already mentioned ; and secondly, within certain Umits, — though this factor has been disputed, — the parallax of indirect vision : the relative position of the retinal images of objects seen by the same eye in indirect vision changes, if ac- commodation is changed, or if the eye or the object moves ; and it is supposed that this shift of position may play a part, in monocular vision, similar to that played in binocular vision by the disparity of retinal images. But, whatever its resources may be, monocular localisation is normally very far from accurate. If a curtain ring is suspended in the median plane of the observer's body, and he is given a pencil and required, with one eye closed, to thrust the pencil through the ring, the pencil will pass at surprising distances before or behind it.^ All the direct criteria of depth-perception have a limited range of effectiveness. Accommodation can hardly come into account for objects more than 2 m. away, and the parallax of indirect vision is of appreciable importance only for objects that lie at arm's ' You may often see connoisseurs looking at a picture monocularly, through the curved hand. The hand serves as a tube, whose walls shut out dis- tracting impressions. The main advantage of monocular vision is that the plane of the picture is less evident to it than to binocular vision, so that the secondary indications of distance, upon which the artist must rely for his depth- values, have a better chance to produce their effect. 3i6 Spatial Perceptions length in the lower portion of the field of vision. Convergence, if experiments are to be trusted, becomes useless at a distance of 15 to 20 m. Retinal disparity may work, in theory, up to a dis- tance of some 2700 m. (p. 325) : but in practice it is replaced, long before this point is reached, by the indirect or secondary criteria of the depth perception. § 87. The Stereoscope. — If the visual perception of depth is due to disparity of the retinal images formed by a single object, then the conditions of tridimensional vision can be synthetised, artificially reproduced, without our having recourse to more than two dimensions of objective space. For the two slightly different pictures taken by the two retinas are plane pictures, and not themselves solid facsimiles of the object. Suppose, then, that we make on paper two drawings of one and the same thing, — a figure of the thing as it looks to the right eye, and a figure of it as it looks to the left, — and that we present each drawing to its appropriate eye. The two drawings, reversals of the two retinal images of a single object seen in perspective, must combine to form the representation of such an object; that is, they must give us the illusion, or rather the synthesis, of the third dimension. They do, in fact, combine in this manner; they show what is called stereoscopic relief. The experiment may be performed in a great variety of ways : there are, however, two instru- ments that have an especial importance, — Wheatstone's reflecting stereoscope and Brewster's refracting stereo- scope. An early form of Wheatstone's stereoscope is shown in Fig. 48. Two plane mirrors, into which the two eyes look, are so adjusted that their backs form an angle of 90''. The diagrams slip into grooves in two vertical panels, which move in and out on slides § 87- The Stereoscope 317 along two flat wooden arms. The arms themselves turn about a common centre, which lies in the projection of the line of junction of the mirrors. The rays reflected from the mirrors fall upon the eyes as if they came from a single solid object immediately in Fig. 48. Wheatstone's Reflecting Stereoscope. — C. Wheatsone, Phil. Trans, of the Royal Soc. of London, 1852, pt. i., 3. front ; or, in other words, the eyes see the combined (virtual) image of the two figures as if through and behind the mirrors. The manipulation of the instrument is simple. The diagrams to be combined are slipped into the grooves. The arms are set in the same straight line, and theslides are pushed well out upon them, at equal distances from the mirrors. The panels are placed at an angle of 45" to the mir- rors. The observer sits, ;\ l\ i\ looking into the mirrors, \ ''' \/ ; and slowly moves the ends ; ,'\ /\ ' ofthe arms outwards, away ; ' j\ \ ', from him, until the images combine. Seen for the 6 o Fig. 49. Plan of Wheatstone's Stereoscope. first time, the stereoscopic effect is surprising in its tridimensional reality.' Brewster's refracting stereoscope, although scientifically a less valu- able instrument, has by its cheapness and compactness driven the reflecting stereoscope out of general use. In its modern form, the stereoscope is furnished with a light wooden hood, fitting ^ It must be remembered that the use of mirrors involves a left-right con- version of the stereograms. 318 Spatial Perceptions closely over forehead and nose, which serves to exclude lateral light.^ The eyes look at the stereograms through lenticular prisms (double convex semi-lenses) : the prisms bring it about that, despite the convergence of the lines of regard, the stereograms are imaged on the retinas approximately as if the lines of regard were parallel; the rounding of the prism-surfaces renders the binocular image both larger and more distinct than it would otherwise be. The long bar, upon which the stereographic card slides, allows of the adjustment of the carrier for eyes of different focal lengths. The stereograms usually supplied with the instrument are paired photographs, taken by cameras whose lenses are — or should be — separated by the average interocular distance. If the cameras are set still farther apart, the binocular (enlarged, virtual) image shows an exaggeration of perspective, and the land- scape or building seen in relief has the appearance of a model. It might be supposed, at first thought, that the stereoscope would settle the con- troversy regarding eye-movement (p. 313). There are, however, various reasons why it cannot. For one thing, it does not permit of a rigorous control of the conditions of observation ; the secondary criteria of dis- tance can never be entirely ruled out. Thus it is possible, in the Wheatstone stereoscope, to vary the degree of convergence while the magnitude of the retinal images remains unchanged (this by pushing the arms still farther out, after perspective vision has been attained, and then by bringing them back again into the same straight line), and to vary the size of the images while convergence remains unchanged (this by moving the slides in and out, nearer to and farther from the mirrors) ; but the chief result — in the first case, change of apparent magnitude of 1 The hood-stereoscope was devised by O. W. Holmes in l86i. Fig. 50. Plan of Brew- ster's Refracting Stereo- scope, old model. — D. Brewster, The Stereo- scope, its History, Theory and Construction, 1856. § 8/. The Stereoscope 319 the binocular image ; and in the second, change of its apparent distance — proves very clearly that the perception is largely de- termined by cortical set ; the observer is influenced by his knowledge of tridimensional space. For another thing, though we may exclude eye-movement proper, we can never exclude the motor disposi- tions of the eye ; and these, on the eye-movement theory, may take the place of movements actually performed. Figure 5 1 shows a simple instrument which embodies the princi- ple of three more special apparatus. It consists, besides rods and Fig, 51. Demonstrational Stereoscope, Telestereoscope and Pseudoscope. clamps, of the hood of a refracting stereoscope (with the prisms removed), two hand-mirrors, and two pocket-mirrors. If stereo- grams are placed in clips at the back of the hand-mirrors, we have a Wheatstone stereoscope. If the instrument is set on a window- sill, with the hand-mirrors parallel to the pocket-mirrors and facing the landscape, we have Helmholtz' telestereoscope : the interocular distance is, to all intents, increased to the distance between the large mirrors, and the perception of depth is enhanced. Finally, if the left-hand small mirror and the right-hand large mirror are thrown down, and the remaining mirrors set, facing each other, at an angle of 45° to the median plane of the observer, we 320 spatial Perceptions have Stratton's form of Mach's mirror pseudoscope : the left eye looks directly at its object, while the right eye sees the same ob- ject twice reflected ; hence the right eye is, so to say, displaced to the left of the left eye, and the distance-relations of the object are inverted ; near becomes far, and far, near. Retinal Rivalry and Binocular Colour-mixture. — So far, we have used the stereoscope for the combination of disparate images of a single object. We may also employ it for the imaging of different objects upon corresponding retinal areas. What happens, if we present to the two eyes pictures of identical shape, size, and position, but of varied content ? By far the most frequent result is the phenomenon known as retinal rivalry. Cut a card to the size of a stereoscopic slide (refracting stereoscope), and paste on it, at the right distance apart, two i-cm. squares of red and green paper, the one crossed by vertical and the other by horizontal black lines. Try to com- bine the two, images in the stereoscope. You will find that they oscillate : now the red and now the green will appear ; now the one colour will seem to hang, like a translucent veil, before the other ; now a patch of the one will give way to the other, which spreads gradually over the whole square. A steady binocular image is not obtained. Whether the one or the other image can be held by the attention (which, in this case, means the cortical set underlying the observer's intention to see red or to see green, and the eye-movements aroused in the effort to hold, follow, or find a disappearing image) is a matter of dispute. It seems, however, that long practice may overcome the rivalry ; for ex- pert raicroscopists rarely close the unoccupied eye while they are observing. Under certain conditions, the phenomenon of retinal rivalry is replaced by that of binocular lustre. Suppose that you are looking at a dead-finished surface, which is smooth over its whole extent, but is not quite even : then the one eye may be in the direction of the reflected light, so that to it the surface looks bright, while the other may not be in this direction, so that to it the surface looks dull, or shows the reflection of some coloured object. Such a surface, seen inordinary binocular vision, appears lustrous. If, § 88. The Perception of Space : Locality 321 Fig. s2. then, we place in the stereoscope two pictures of the same object, the one white and the other coloured, — still better, if the one is white and the other black, — we shall get the perception of sheen or lustre. The binocular image of Fig. 52 does, in fact, show a graphite-like polish, although, for most observers, traces of rivalry also persist. Lastly, the phe- nomenon of rivalry may be replaced by that of a binocular colour-mixture. The existence of this mixture has, again, been keenly disputed, but there can be no question of its occurrence. In the author's experience, the best way to secure it by aid of the stereoscope is to combine two small fields of dull and unsaturated colour. The paper squares must be pasted with extreme accuracy upon the cardboard slide ; and the observation should be made with the images a little out of focus, so that the contours of the fields are blurred. Some observers, however, succeed most easily with identical contours of considerable complexity : trials may be made with differently coloured postage stamps. Where the mixture is attained, the re- sultant colour is the same as in ordinary colour- mixture, but its brightness is the mean of those of the combined colours. § 88. The Perception of Space : Locality. — Our visual perception of place or position is very highly- organised ; stimuli that are dis- tinguished as spatially different, in daylight vision, are also definitely Fig. S3. Hering's Binocular Colour Mixer. L, R, the two eyes ; b, dark box ; gg' , coloured glasses (red and blue) ; pp, supporting plate of clear glass ; sss, squares of white paper. — Her- mann's Hdbch. d. Physiol., iii., I, 1879, S93. 322 Spatial Perceptions placed in relation to one another.^ With the skin it is other- wise ; the cutaneous perception of locality is less developed ; and we are able, in the course of a single experiment, to bring out various modes and degrees'of localisation. Suppose, for instance, that a pair of compasses, having delicately rounded points of hard rubber, is set down upon the skin of the fore- arm, with the points i mm. apart. We perceive, with eyes closed, a single, sharp pressure upon the forearm. Locali- sation may be effected in several ways : we may feel an im- pulse to move the hand of the opposite side towards the part touched, or we may have a visual picture of the arm and of the point resting upon it, or the pressure may touch off at once some form of words (" Halfway up the arm, in the middle"). The visual picture and the words are, of course, secondary criteria of cutaneous position, and the feel of the localising movement, though much more nearly primitive, is also, if we may trust the conclusions of § 85, in the last resort of secondary character. Here, then, is what we may call the absolute perception of cutaneous locality, the perception of the position of a single pressure. Now let us consider the relative perception : let the compass points be gradually separated, by small steps, and let us note the results. We get, first of all, a larger, blunt point ; this gradually passes into a small surface of oval form : then comes a thickish line; then the perception of two sharp points, with a faint linear connection between them ; 1 This statement is true as a first approximation to the facts. We ought, by rights, to take account of indirect as well as of direct vision, of vision of luminous points in the darlc as well as of vision in the daylight, of pathologi- cal states of the retina, of the a is always, context ; one mental process is the meaning of another mental process if it is that other's context. And context, in this sense, is simply thenientaL process which- accrues to the given process through the situation in which the organism finds itself. Originally, the situation is physical, external; and, origi- nally, meaning is kinaesthesis ; the organism faces the situation by some bodily attitude, and the characteristic sensations which the attitude arouses give meaning to the process which stands at the conscious focus, are psycho- logically the meaning of that process. For ourselves, the situation may be either external or internal, either physical or mental, either a group of adequate stimuli or a constel- lation of ideas ; image has now supervened upon sensation, and meaning can be carried in imaginal terms. For us, A popular account of the Herbartian psychology is given by J. Adams, The Herbartian Psychology applied to Education, 1898, eh. iii. 368 The Psychology of Perception therefore, meaning may be mainly a matter of sensations of the special senses, or of images, or of kinaesthetic or other organic sensations, as the nature of the situation demands. Of all its possible forms, however, two appear to be of especial importance : kinaesthesis and verbal images. We are locomotor organisms, and change of bodily attitude is of constant occurrence in our experience ; so that typical kinaesthetic patterns become, so to say, ingrained in our consciousness. And words themselves, let us remember, were at first bodily attitudes, gestures, kinaesthetic con- texts : complicated, of course, by sound, but still essentially akin to the gross bodily attitudes of which we have been speaking. The fact that words are thus originally con- textual, and the fact that they nevertheless as sound, and later as sight, possess and acquire a content-character, — these facts render language preeminently available as the vehicle of meaning. The words that we read are both perception and context of perception; the auditory- kinaesthetic idea is the meaning of the visual symbols. And it is obvious that all sorts of sensory and imaginal complexes receive their meaning from some mode of verbal representation : we understand a thing, place a thing, as soon as we have named it. Hence, in minds of a certain constitution, it may well be that all conscious meaning is carried by total kinaesthetic attitude or by words. As a matter of fact, however, men- tal constitution is widely varied, and meaning is carried by all sorts of sensory and imaginal processes. The gist of this account is that it takes at least two sensations to make a meaning. If an animal has a sensation of light, and nothing more, there is no meaning in consciousness. If the sen- sation of light is accompanied by a strain, it becomes forthwith a § I03. Meaning 369 perception of light, with meaning ; it is now ' that bright some- thing ' ; and it owes the ' that something ' to its strain-context. Simple enough ! — only be clear that the account is not genetic, but analytic. We have no .reason to believe that mind began with meaningless sensations, and progressed to meaningful perceptions. On the contrary, we must suppose that mind was meaningful from the very outset. We find, by our ana,lysis (§ 96), that sensation does not mean ; and we find, in synthesis, that the context which accrues from the situation, however simple or however complex the context may be, makes it mean, is its meaning. What, then, precisely, is a situation ? The physical or external situation is the whole external world as an organism, at any given moment, takes it ; it consists of those stimuli to which the organ- ism, by virtue of its inherited organisation and its present disposition, is responsive, — which it selects, unifies, focaUses, supplements, and, if need be, acts upon. The mental or internal situation is, in like manner, some imaginative or memorial com- plex which is fitted, under the conditions obtaining in the nervous system, to dominate consciousness, to maintain itself in the focus of attention, to serve as the starting-point for further ideas or for action. To put the definition in a word, a situation is the mean- ingful experience of a conscious present. ^ But is meaning always conscious meaning .' Surely not : meaning may be carried in purely physiological terms. In rapid reading, the skimming of pages in quick succession ; in the rendering of a musical composition, without hesita- tion or reflection, in a particular key ; in shifting from one language to another as you turn to your right- or left-hand neighbour at a dinner-table : in these and similar cases meaning has, time and time again, no discoverable repre- sentation in consciousness. The course and connection of ideas may be determined beforehand and from without ; a word, an expression of face, an inflection of the voice, a bodily attitude, presses the nervous button, and conscious- 370 The Psychology of Perception ness is switched, automatically, into new channels. We find here an illustration of an universal law of mind, of which we shall have more to say when we come to deal with Action : the law that all conscious formations, as the life of the organism proceeds, show like phenomena of rise and fall, increase and decrease in complexity, expansion and reduction ; so that, in the extreme case, what was originally a focal experience may presently lapse altogether. We learned our French and German with pains and labour ; the conscious context that gave meaning to words and sentences was elaborate ; but now all this context has dis- appeared, and a certain set of the nervous system, itself not accompanied by consciousness, gives the sounds that fall upon our ears a French-meaning, or changes us into German-speakers. This predetermination of consciousness by influences that, during the course of consciousness, are not themselves conscious, is a fact of extreme psychological importance, and the reader should verify it from his own experience. It has a threefold bearing upon the psychological system. First, it reminds us that consciousness is a temporal affair, to be studied in longitudinal as well as in transverse section. It is part of the direct business of psychology to trace the fate of meaning from its full and complete conscious represen- tation, through all the stages of its degeneration, to its final disap- pearance. Secondly, our psychology is to be explanatory, and our explanations are to be physiological (§ 9). To explain the way in which consciousness runs, the definite line that it takes, we must have recourse to physiological organisation ; and the tracing of the stages of mental decay helps us to follow and understand the or- ganising process. Thirdly, if we lose sight of nervous predisposi- tion, we shall make grave mistakes in our psychological analysis ; we shall read into mental processes characters that, in fact, they do not possess. Turn back to the simple instance given on pp. 274 f. Here we must either say that the meaning of the experi- § 104. The Form of Combination 371 ment, after the week's work, is carried for the observer in purely physiological, non-conscious terms ; or we must say that his obser- vation is untrustworthy, that there is a mental context which he has overlooked. But if we take this latter alternative, we shall be constructing mind as the naturalist in the story constructed the camel ; we shall be inventing, not describing. § 104. The Form of Combination. — Our account of the psychology of perception is now, in the author's view, complete. It has embraced four principal points. First, under the general laws of attention and the special laws of sensory connection, sensations are welded together, con- solidated, incorporated into a group. Secondly, this group of sensations is supplemented by images. Thirdly, the supplemented group has a fringe, a background, a con- text; and this context is the psychological equivalent of its logical meaning. Fourthly, meaning may lapse from consciousness, and conscious context may be replaced by a non-conscious nervous set. If we translate this account into genetic terms, we have, as the earliest form of percep- tion, some sensory complex in a kinaesthetic setting. Then comes the invasion of consciousness by images, which mod- ify both complex and setting, and may, in course of time, largely replace the sensory elements of the one and actu- ally displace the other. The images themselves are very far from stable ; they shrink and decay ; they tend, more especially, to reduce to a common denominator, to verbal ideas ; a sort of symbolic shorthand supersedes the earlier picture-writing of mind. Finally, the central complex may appear as a mere skeleton of its former self, a mere indica- tion of its primal complexity, and the setting may not appear at all ; meaning may be carried in terms of physio- logical organisation. 372 The Psychology of Perception There are, however, some psychologists who would not regard the account as complete. A square, they say, is more than four linear extensions, sensibly of the same length, and occupying certain relative positions in the vis- ual field ; a square is square ; and squareness is a new character, common to all squares, but not to be explained by attention, or by the laws of sensory connection, or by those of imaginal supplementing. A melody, again, is more than rhythm and consonance and scale ; a melody is melodic ; we recognise its melodic nature as such ; the melodic character is something new and unique, common to all melodies, but not found elsewhere. Hence they find it necessary to postulate " a form of combination as a dis- tinct mental element." "The presentation of a form of synthesis," they argue, " is as distinct from the presenta- tion of the elements combined, considered apart from their union, as the presentation of red is distinct from the pres- entation of green." ^ In the author's judgment, this attitude betrays a confu- sion of the analytic and the genetic points of view. We cannot generate the square from lines, or the melody from rhythm and scale ; but neither is that what we try to do. The square and the melody are given, as perceptions. Our psychological task is to analyse these given perceptions, to discover their elements, and to formulate the laws under which the elementary processes combine. That done, we can write, for ' square ' and ' melody,' 'these and these ele- ments connected in these and these uniform ways,' and we can go on to search for physiological conditions (§ 9). We have solved our problem in analytical terms ; we have not first defined the terms, and then put them together to ' G. F. stout, Analytic Psychology, ii., 1909, 48. Cf. i., 1896, ch. iii. References for Further Reading 373 produce something that was not contained in the definition. — The author cannot, in his own introspection, identify the form of combination as a distinct mental element. It is, however, only right to say that the belief in a new mental content, or new mental character, peculiar to perception, is shared by many psychologists of standing. References for Further Reading §§ 102-104. On the general topic, see W. James, Principles of Psychology, i., 1890, ch. xiii. ; ii., chs. xvii., xix. ; H. Ebbinghaus, Psy- chologie, ii., 1908, § 70. On the psychology of meaning, see the author's Lectures on the Experimental Psychology of the Thought-processes, 1909, Lect. V. On the form of combination, see I. M. Bentley, The Psy- chology of Mental Arrangement, in American Journal of Psychology, xiii., 1902, 269 ff. ASSOCIATION § 105. The Doctrine of Association. — It often happens that we wish to recall something that we are sure we know, but that at the moment escapes us. Aristotle, in his tract On Memory and Reminiscence, suggests a mode of proce- dure for such cases : we should start out from something that is similar to the idea we want, or that is its opposite, or that has been contiguous with it in space or time.^ Aristotle writes as if these ways of arousing memory were entirely familiar to his readers ; and so, no doubt, they were ; popular psychology is full of just such maxims (p. 286). Nevertheless, the Aristotelian rules proved to be immensely important for the future history of psychology. They were gradually transformed into laws of the associ- ation of ideas ; and the association of ideas itself came to be the guiding principle of the British school of empirical psychology. So well did it work, as an in- strument of psychological analysis and interpretation, that Hume compared it to the law of gravitation in physics : "here," he said, "is a kind of attraction which in the mental world will be found to have as extraordinary effects as in the natural, and to show itself in as many and as various forms. ' ' ^ All the great names in British psychology, from Hobbes down to Bain, are connected with this doctrine of the association of ideas.^ 1 W. A. Hammond, AristotUs Psychology, 1902, 205. ^ D. Hume, A Treatise of Human Nature, [1739] bk. i., pt. i., § 4. ' Let the roll be called ! Thomas Hobbes, John Locke (who introduced the phrase ' association of ideas' ), George Berkeley, David Hume, David Hartley (the founder of modern associationism), Thomas Brown, James Mill § 105- The Doctrine of Association 375 There are, then, four traditional laws of association. An idea calls up or suggests another idea by similarity, by contrast, by temporal or spatial contiguity. " A picture naturally leads our thoughts to the original " (Hume) : here is association by similar- ity. " The palace and the cottage, the cradle and the grave, the extremes of indigence and of luxurious splendour, arise, in ready succession, to the observer of either " (Brown) : here is association by contrast. " From St. Andrew the mind runneth to St. Peter, because their names are read together ; from St. Peter to a stone, for the same cause ; from stone to foundation, because we see them together" (Hobbes) : here is association by spatial and temporal coexistence. " A musician used to any tune will find that, let it but once begin in his head, the ideas of the several notes of it will follow one anotherorderly in his understanding" (Locke) : here is association by temporal succession. The tendency has been, however, to reduce these four laws to two, or even to one. The law of contrast, especially, has been merged in that of similarity ; if things contrast, it is argued, they must be similar, at least to the extent that they belong to the same general class ; black calls up white and not sour ; sour calls up sweet and not black ; so that association by contrast is really associ- ation by similarity. To this reduction there are two objections. First, the argument is logical and not psychological ; the interven- tion of the class-idea is not attested by introspection. And, secondly, the contrast referred to in the one law is not on a par with the similarity referred to in the other ; the contrast is, as we have already seen (pp. 232 f.), an affective opposition, whereas the similarity is ideational. Nevertheless, we can do away with the law of contrast. The cases that fall under it are simply cases in which the extremes of our experience meet, cases of contiguity. Such cases are very common : letters are printed black on white, (the typical representative of the school), John Stuart Mill, Alexander Bain, Herbert Spencer (these three no longer pure associationists) . References will be found in the arts. Association {of ideas') and Associationism, in the Dictionary of Philosophy and Psychology, i., igor, 78, 80. All these men are worthy of study; only let the student beware of the fatal error that, because they read easily, they are easy reading. 376 Association the most brilliant lights give the deepest shadows, we are hungry and we eat, we feel cold and we make haste to get warm, we come to the palace through streets of mean houses, and so on. There is no need of a special law of contrast. Again, coexistence in space means coexistence in time. Hence there is no need, either, of a special law of association by spatial contiguity ; temporal contiguity, simultaneous or successive, covers all the cases. The four laws thus become two, those of similarity and of temporal contiguity. Efforts have been made to carry the reduction still further ; we return to the point in § 107. § 106. The Idea. — According to the teaching of this book, an idea differs from a perception only by the fact that it is made up wholly of images (p. 48). Look across the room, and you perceive the table ; shut your eyes, and you ideate the table. The psychology of ideas is, therefore, so far as this difference allows, the counterpart of the psychology of perceptions. Ideas are simple or composite ; they are subject to the law of growth and decay ; they get their meaning from their context, and the context may consist of other ideas, or may be carried in physiological terms. Now it needs but little reflection to see that these ideas are not at all the same thing as the ideas of the preceding Section. The ideas which we ourselves are defining are fluid, changeable processes, which derive their meaning from conscious context or from cortical set. The ideas which are associated, in the traditional doctrine of the association of ideas, are already meanings : the idea of the painting's original is the idea which means that original, the idea of St. Peter is the idea that means St. Peter : or rather, if one may put it clumsily for the sake of clearness, the former idea is just the man-fainied-meaning, and the latter idea is the St-Peeer-mea.mng. Meaning here is not § io6. The Idea 377 the context of the idea, nor is it an external predetermina- tion of the consciousness in which the idea occurs ; mean- ing is idea, idea is meaning. And since meaning is stable and permanent, since the man-painted is always the same man, and St. Peter is always that identical St. Peter, the psychologists of association naturally treated the ideas also as stable and permanent; the ideas were bits of meaning, separate and impenetrable as physical atoms. It is hardly a caricature if we say that ideas were Uke beads, strung on the thread of association, or like steel blocks, held in certain arrangements by the magnetic force of association. There are, in fact, two uses of the term ' association,' which are both confused and confusing in the writers of the associationist school. On the one hand, association is the gentle force of attraction inherent in an idea, the affinity of idea for idea, the tendency of one idea to suggest another; the steel blocks are magnetised from the outset. On the other hand, association is the principle of connection among ideas, is that which ties, binds, conjoins, links, couples idea with idea ; and this something may be found-either in the nature of the mind (the magnet) or in the nature of the brain (the string for the beads). The last concep- tion comes very near our own ; ^ but mark the difference ! Per- ception is, for us, primarily, a group of sensations, — or, better, perception is such and so-many sensations found uniformly to- gether in such-and-such ways. Association, then, will also be, for us, a group of ideas, — or, better, association will be such and so- many ideas found uniformly together in such-and-such ways. The explanation of association, like that of perception, must be ^ It is because many of the conceptions of associationism are very like those of modern psychology, because the terminology is largely the same, because the writers' attitude is oftentimes, as if in despite of their associa- tionism, the attitude of modern psycholbgy itself, and because, nevertheless, the taint of logical construction pervades the whole of their work, — it is for these reasons that the student must read warily, with all his psychological wits about him. 378 Association sought in the nervous system. But the underlying nervous processes do not cement or string the ideas together ; the ideas are found together, and the conditions under which they are found together are nervous. This is the difference. We shall have much to say, in what follows, of the na- ture and behaviour of the idea. It is sufficient, just now, to have indicated its general character as a mental process, and to have shown how it differs from the idea of asso- ciationism. § 107. The law of Association. — The traditional laws of the association of ideas are, after all, not. descriptive formulas, as scientific laws must always be (p. s), but attempts at explanation. If we say that the idea of Julius Caesar calls up the idea of [Alexander the Great by simi- larity, we are offering the similarity of the ideas as an explanation of their concurrence in consciousness ; and that road leads nowhere (p. 39). Let us try, hovvever, to get a descriptive formula for the facts which the doctrine of association aims to explain. We then find this : that, w henever a sensory or imaginal pro cess occurs in con- sciousness, there are nkely to appear with it (of co urse, in imaginal terms) all those sensory jj id imaginal pro cesses wh^ch occurred together wit h it in any earlier co nscious p resen t. This we may term the law of association. That is the text : now follows the commentary. Note, first, that we have confined the sphere of the law to sensory and imaginal processes, to perceptions and ideas. Some psychologists believe that it should be extended to include the affective processes. There is, truly, no question that feelings (in the widest sense, p. 228) play a large part in the associative consciousness; only, in the author's opinion, they play this part by virtue of their sensory and imaginal components, and not in their affective character. How- § lo/. The Law of Association 379 ever, so little is known about the psychology of feeling that the reader will do best to suspend judgment. Secondly, the law has said nothing about attention. In the author's opinion, association always implies a high degree of clear- ness ; the processes that were together in the conscious present must have been attentively together, if the law is to hold. But, again, the point is disputed, and the experimental evidence is not conclusive. Thirdly, the law must be amplified in the following way. It is not necessary, for the reinstatement of a previous consciousness, that one of its terms should literally be repeated, in the sense of p. 19 ; it is enough that a process appear which is like one or other of its terms. If I meet my friend to-day, I am at once reminded of the conversation that we had at our last meeting, a month ago. But if some one shows me to-day a recent portrait of my friend, the same thing happens : ' A good picture,' I say; ' I saw him a month ago, and we had a very interesting talk.' This extension of the law of association, from psychological identity to psychological similarity, is clearly seen in young children, who call all the men of their acquaintance ' papa,' and call every animal — live animal, toy, or picture — by the first animal-name that they have learned. It must be accounted for on the hypothesis that the nervous conditions of similar ideas are in part the same, and that, the more alike the ideas, the more nearly identical are their conditions. This mention of similarity brings us back to the discussion of § 105. Efforts have been made, we said, to reduce the two laws of contiguity and similarity to one. Now the law of contiguity can, with a little forcing, be translated into our own general law of association. Let the translation be made, and the law stands. What, then, of the law of similarity? This, be it remembered, is very different from our own amplified or "extended law of associa- tion. We say that ideas may be started on the same track from similar beginnings ; the old law of similarity says that the course of ideas ends with similars, that mental like attracts like. No doubt this statements holds, in the rough, of a great many instances of association : the idea of Julius Caesar does bring in its train the idea of Alexander the Great ; and we have noted congruity with 380 Association the present contents of consciousness as one of the determinants of attention (p. 270). Nevertheless, all cases of similarity prove, on examination, to involve contiguity. Caesar suggests Alexander, not — it is true — by way of the class-idea ' great commander,' but simply because some component of the idea of Caesar has previously been together, in a conscious present, with that of Alex- ander. We may, then, if we like, say that all associations reduce to associations by contiguity, • — ■ being careful, in our own thought, to translate this law into psychological terms. On the whole, how- ever, it is advisable to drop the traditional laws, and to retain only the formula of the text; there is a risk in pouring the new wine into the old bottle. § 108. The Experimental Study of Association. — The ideas of associationism are meanings ; and meanings, from our point of view, are conscious contexts or nervous deter- minations of consciousness. Whichever they are, they sadly complicate enquiry into the conditions of association. We have a general law ; but we want to know how it comes about, in the particular case, that this and not that idea arises on the recurrence of the other, that Caesar suggests now Alexander and now Napoleon. We want to get to the bare essentials of the association. Some twenty-five years ago, Ebbinghaus solved this prob- lem by the introduction of nonsense syllables. He made up over 2000 meaningless ' words,' all consisting of a vowel or diphthongbetween two consonants ; the German language uses these combinations far less than the English. Here, then, were pure perceptions, sights and sounds that had no meaning and no associates ; here was material so varied and yet so simple, so rich and yet so uniform, that experiments could be made under laboratory conditions, and the results of one experiment could be compared, directly, with the results of another. It is not too much to say that the re- § io8. The Experimental Study of Association 381 course to nonsense syllables, as means to the study of asso- ciation, marks the most considerable advance, in this chapter of psychology, since the time of Aristotle. It must not be supposed that the nonsense syllables work auto- matically. We are inveterately given to meaning; and the ob- server who sits down to learn a series for the first time shows a terrible ingenuity in reading sense into what by hypothesis is non- FlG. 60. Apparatus for the Serial Exposure of Nonsense Syllables. The syllables are printed upon the periphery of a cardboard disc, which is placed in the box to the right, and are viewed through the radial slit in the lid. The movement of the disc is governed by the metronome ; as the pendulum swings, and electrical contact is made between the platinum strips and the mercury pools at the base of the instrument, the disc turns, with a jerk, just so far as to expose a new syllable. At the end of the series, the mechanism may be arrested by opening the Icey to the left. The two wires at the bottom of the figure are led to a battery. — P. Ransch- burg, Monatsschr. f. Psychiatr. u. Neurol., x., 1901, 321. sense. A recent writer quotes, as a typical set of English nonsense syllables, the series : leb, rit, mon, yup, kig, des, wer, zam. But rit suggests writ, mon is Scotch for man, yup suggests yap or yelp, kig — if you have a cold — is king, wer is obviously were. And if you know anything of German, leb, des, wer, zam are directly suggestive of meaning. The series is, very certainly, not the kind of series for the beginner, who is constantly hunting about for meaningftil connections. Ebbinghaus reports that the syllables dosch pam feur lot were connected by the meaning das Brot 382 Association [Fr. pain !] Feuer loscht, the bread puts out fire. Indeed, here, as in most psychological experiments, the novice is likely to do anything rather than what is required of him ; he will search for meanings, stress the position of syllables, mark the rhythm, shift his imagery (§ 114). There are great individual differences; but, in general, it is only after a good deal of practice that the observer be- comes the sheer mechanical associator ; and it is therefore neces- sary to make a careful choice of material even within the sphere of the directly meaningless. However, the observer may be trained. And methods have been worked out, for the study of association by means of nonsense syllables, that are as rigorous as those em- ployed for the study of the intensity or quality of sensation. Nevertheless, we cannot stop short with these nonsense syllables. The results derived from meaningless material, while they are essential to our analysis of the more com- plicated results from words, pictures, etc., must themselves be scrutinised in the light of the ordinary meaningful as- sociations of everyday life ; ^ they are fundamental, but they are also artificial; until further test, they hold only for the restricted conditions under which they are obtained. However, this work of comparison, of mutual control, offers no special difficulties ; indeed, the rules discovered in the laboratory have already been applied, with success, to cer- tain practical problems. § 109. Eesults : the Conditions of Impression. — Suppose that you read through a list of nonsense syllables, again and again, until you can recite it without error. The read- ing will have established a number of associative connections between the terms of the series. But it has also, plainly, established the terms themselves. These terms have, as stimuli, impressed the nervous system, imprinted themselves on it, stamped it in a determinate way. iWe return to this part of the subject in § 123 below. § 1 09. Results: The Conditions of Impression 383 The correct recitation depends, then, not only upon as- sociative connections, but also upon impression. A term may be but weakly associated to its preceding term, and yet, if it has made a strong impression, — if, as we may say figuratively, its idea is almost ready to appear of itself, — may be brought to consciousness by the weak associative tendency ; and, conversely, a term may be but weakly im- pressed upon the nervous system, and yet may be brought to consciousness by a strong associative tendency. It is impossible, in experiments of the sort under discussion, to separate the two factors in the result; the conditions of | impression are also the conditions of association. We may say, however, that impression depends up on the lengt h of the series, the position nf thp tprms vyjt hin 'it, the rat e of su ccession of the terms, their grouping into compl ex units, the num ber an d distribu tion of the readings, the active p articipation of the observer^ and th p; rP"'^'' (t^t^l "r partial) of repetition . Attention, we may remind the reader, is presupposed. Impres- sion then depends, first, on the length of the series. While 6 or 7 syllables can be recited correctly after a single reading, a larger number throws the observer into confusion. The first and last terms of the series have the advantage over the others ; they may, indeed, be the only terms that can be recited after a single read- ing of a i2-syllable series. The impression is deepest if the syl- lables are first presented at a moderate rate (perhaps 2 in the i sec), and if this rate is slowly increased as the readings proceed. It is of assistance to introduce a subjective rhythm. Impression deepens, fiirther, with repetition. The first reading is more im- portant than any single later reading; after that, there is for a while little if any improvement ; then the results take a sudden step up ; and thenceforward progress is fairly steady until the limit of the experiment is reached. The distribution of the read- 384 Association ings in time is also of great importance : thus, it is better to dis- tribute 24 readings in pairs to 12 days than to take them in fours on 6 days ; and it is, again, better to do this than to take them in eights on 3 days. The same rules hold, wit. . the necessary changes, for meaning- ful material. While 8 or 9 one-syllable words, and 10 or 12 figures, can be recited correctly after a single reading, a larger number brings confusion. We return to this point later (p. 387). The rate of presentation may be much quicker : in the reading of poetry, e.g., 140 to 150 iambic measures in the i min. (4 or 5 syllables in the I sec). The grouping of the material is given, not only by rhythm, but by the meaning of the successive passages. There remain the two factors which we have called the active participation of the observer and the mode of repetition. It is found that a recitation is far more effective for impression than a reading. The reason may be, in part, that attention is greater ; in part, that the auditory and kinaesthetic stimuli reinforce the visual. It seems to the author, however, that the chief effect of the reci- tation is to equalise the attentions ; every term in the series must be brought out sharply and clearly ; the observer discovers his weaknesses, and has the opportunity to overcome them. Finally, it is found that connected, meaningful material is most impressive if it is read as a whole, from end to end, in the successive repeti- tions, while nonsense syllables and disconnected meaningful ma- terial (dates of events, words of foreign languages) are best taken discretely, read over and over a little at a time. — The nervous modification which we have here named ' impres- sion ' is, clearly, the first term in the series of nervous changes which condition the process of learning. If we read the list of syllables again and again until we can recite it correctly, we have learned it. Learning, however, is a very complex affair, depending upon im- pression, upon associative tendency, upon the retentiveness of nerve-substance, and upon cortical set. Hence we have avoided the use of the word in the present Section. §110. Results: the Conditions of Associative Tendency. — Anything that makes for the impression of two stimuli, § no. Results: Conditions of Associative Tendency 385 during the conscious present, will also serve to establish an associative tendency between them ; so that the recur- rence of the one, whether as perception or idea, will be likely to arouse the idea of the other. The impressing of our series of syllables has, accordingly, established certain associative tendencies. The strongest of these, as might be supposed, is that which leads from term to term in the order of presentation ; but there is good reason to believe that every term is, in some measure, connected with every other term of the series. We find in the experimental results cases of association, not only of immediately successive ideas f di rect associat ionl. but also of ideas separated, within the conscious present, by other ideas (re mote associatio n'^ ; this latter is relatively weak, but it is still definitely discoverable. To put the matter in terms of the alpha- bet, we find associations, not only of a and b, of b and c, ol y and z, but also of a and d, of v and z. And, what is more important, we find that the associative tendencies may work retroactively ; there are associations of 2 with y, of 2 with x, and so forth. The series of syllables has therefore been impressed, not as an interrupted series, but as a very complicated meshwork, functionally inter- connected through all its parts. There is yet a further complication. The series is impressed upon a brain which is already the seat of a vast concourse of as- sociative tendencies ; and the incoming stimuli may thus excite to full or partial activity some preexisting tendency whose arousal was neither expected nor intended. The observers not infrequently re- port, e.g., asso ciations of positio n, of the place of a syllable in the series; the cue may be given, according to the circumstances of the experiment, by a verbal idea of number, by the spatial arrange- ment of the syllables, by inflection of the voice. Under certain conditions, the subarousal of such a tendency determines an as- sociation, while the place-idea does not itself appear in conscious- ness. Suppose that a is associated to b, a to j8, and that both pairs of letters have been associated to the place-ideas first, second. 386 Association Then, in the given case, the sight of a may suggest the idea of j8, although the observer has not thought of 'first.' Mediate Associa tion. — Some psychologists believe that an asso- ciation may be set up, originated, by unconsc ious (purely physio- logical) intermediaries. I examine a picture, we will say, which the artist has signed ; my eyes travel over the signature, but I fail entirely to remark it. At some later time I am examining another picture, signed in the same way by the same artist ; again my eyes travel over the signature, but again I fail to remark it. Neverthe- less, the second picture suggests the first ; the signature has im- pressed my brain, although it has not aroused a perception ; the ideas of the two pictures are connected by this unconscious link. Here is a case of mediate association. The question has been put to the trial of experiment, and the results are mainly negative ; it is, however, so difficult to meet the conditions of a crucial test, that difference of opinion is natural and justifiable. In the author's judgment, association requires attention (p. 379) ; mediate association, of the kind described, does not occur. The alleged instances may be interpreted as associations whose c onscious me diation (odour, organic sensation) has been overlooked, or as remote ass ociation s, or as associations due, in the way just described, to the gnbarnnsal nf associative tendencies already establishe d. A fourth possibility will be dis- cussed later (p. 400). If, now, a series of nonsense syllables establishes this complicated network of associative tendencies, a stanza of poetry or a paragraph of prose must set up excitations of far greater complexity. And the pattern of the excitations will vary, according as the meaningful material is familiar, and therefore throws into play a total cortical disposition, or is unfamiliar, and therefore starts up only partial and fragmentary associations. We cannot trace these effects in detail ; but we have evidence both of the mutual rein- forcement and of the mutual interference of associative tendencies. § no. Restdts : Conditions of Associative Tendency 387 We have had an instance of interference in the confusion that fol- lows the first reading of a long series of words or syllables (pp. 383f.). So long as we are within the range of attention (§ 80), there is no difficulty. But when we pass beyond it, the law of retroactive inhibition comes into effect. The associative tendencies need a certain time to establish themselves, to settle down ; and if this time is not allowed, but stimulus treads on the heels of stimulus, there is no impression of a pattern, and no associations are formed. A recently acquired association may even be abolished — as most of us know to our cost — by intensive occupation with an entirely different topic. You have just got to your point, to the phrasing, the- insight, the argument, that will clinch things ; you are dis- tracted by some irrelevant business ; and when you come back to your work, the point has gone. So nicely balanced and so easily disturbed are the associative tendencies, that you may never re- cover it ; try as you will to reinstate the conditions, you cannot get the exact pattern back again. The compensation is that the tendencies, left to themselves, fall into their own patterns. School- boys, with a keen sense for economy of effort, learn their lessons only partly overnight, and trust to a hasty review in the morning ; the associative tendencies work while their owners sleep. Here, too, is the secret of the practised speech-maker. Knowing that he has to talk on a certain subject at a certain date, he runs over his present ideas in ten minutes of concentrated attention, and drops them ; then, on the appointed day, he finds that the associa- tive tendencies have prepared his address. With meaningful material, interference may arise in other ways. Take the alphabet, again : a is connected with b through the fre- quent repetition of abc, but is also connected with z by the phrase • a to 2.' Let a appear in consciousness ; what happens ? It may be promptly followed by b or z ; the one of these ideas may, as we have expressed it, be more nearly ' ready ' than the other. If the terms of the two associations are complex, the incoming idea may derive from both of them : a may, so to say, call up an idea that is partly b and partly 2. But, if the a- tendency and the 2-tendency are of approximately equal strength, they will cancel each other, and there will be no association. A question often 388 Association leaves you dumb, not because you have no answer, but because you have so many answers that no one of them can force through to expression. This sort of interference is known as terminal inhibition, in con- tradistinction to another kind, which is called initial inhibition. If a is already connected with b, then it is difficult to connect it with k ; b gets in the way. You have some particular fault of style, or you have fallen into the habit of spelling wrongly some particu- lar word ; you want to correct the fault, to spell aright. But every time that you are off guard, the mistake recurs ; the existing asso- ciation a-b heads off the desired association a-k. This law, then,- cuts across the law of remote association. The first impression of the alphabet sets up, it is true, not only the direct association a-b, but also the remote association a-k. As, however, the alpha- bet is more and more often repeated, the direct association more and more strongly inhibits the remote, so that it presently requires more readings to establish the connection a-k than were needed for the original connection a—b. On the other hand, the associative tendencies may reinforce one another. Association may be convergent ; a whole constellation or complex of tendencies may work together in the interests of a single idea, and this complex, as we have repeatedly seen {e.g., p. 274), need not by any means appear as a whole in consciousness. Chil- dren who are brought up to speak two languages rarely mix their words ; as they have begun, so do they continue, a sentence ; the first utterance has behind it the directive pressure of a multitude of cooperating tendencies. More than this, association may be at first divergent, and then convergent. A perception may stir into activity -a number of tendencies, or a number of constellations ; and these may, in their turn, all converge upon a single idea. Here we get a glimpse into the physiological basis of conscious context, of psychological meaning (§ 103). The words of a sen- tence, the sentences of a paragraph, the paragraphs of a chapter, the chapters of a book, arouse innumerable tendencies in the nervous system of the reader. Sometimes a special constellation gains the upper hand, and the reader is sidetracked by his own ideas ; in general, the writer has his way, and the divergent ten- § III. The Associative Consciousness 389 dencies are continually recombined. However, this is not the whole story of meaning; the reader's total attitude is also of great importance (§ 141). III. The Associative Consciousness. — There are as many modes or forms of association as there are ways of being together within a conscious present. What these ways are, we already know ; they have been outlined in our discussion of perception. We may say, then, that there are as many forms of association as there are forms of perception and idea ; the pattern of the associative conscioussness may be spatial, temporal, qualitative, or mixed. The pure percep- tion is itself an association of sensations, and the idea is an association of images. But is there no psychological difference between percep- tion and idea, on the one side, and the association on the other.? Not, certainly, in composition: the elementary processes that analysis reveals are the same in both, — sensations and images. Not, necessarily, in complexity : many of the instances of association given in the text-books are simpler, contain fewer elementary processes, than the more complicated perceptions. Not, again, in mode of connection of the elements : the laws governing connec- tion are the same throughout. And not, necessarily, in closeness of this connection : the names of familiar things are as closely bound up with their perceptions as the sensory elements in the perceptions are bound together. The differ- ence is, in fact, rather a psychologist's than a psychological difference. We must build up a psychology by stages, in orderly fashion ; and it is convenient to distinguish, first, the bare elements, sensations and images ; next the con- nection of the bare elements, perceptions and ideas ; and then, later, the connections of elements that have already 390 Association been connected, the associations of ideas. If we may use a figure, which roughly expresses the truth, we can say that the elements of the perception have never been together before, while the elements of the association have manifold habits of connection already upon them. The doctrine of association has, however, played so im- portant a part in the history of psychology, and the influence of tradition is so strong, that many psychologists tend, as if instinctively, to differentiate the idea from the association of ideas. The tendency shows itself in two ways : first, in the overemphasis of successive, as compared with simultaneous association ; and secondly, in the attempt to classify and tabulate the various forms of association. Most students of psychology, if they hear the phrase ' association of ideas,' think at once of the successive association ; and this, by its very nature as a train or succession, is more complex and more variable in its course than is the idea. Yet it is certain that the simultaneous association is the typical association, and that the successive association, as illustrated in the books, is of rare occur- rence, a limiting case of association at large. " In a discourse of our present civil war," wrote Hobbes in 165 1, "what could seem more impertinent than to ask, as one did, what was the value of a Roman penny? Yet the coherence to me was manifest enough. For the thought of the war introduced the thought of delivering up the king to his enemies ; the thought of that brought in the thought of the delivering up of Christ ; and that, again, the thought of the thirty pence, which was the price of that treason. And thence easily followed that malicious question." Here, no doubt, Hobbes has his finger on the coherence, the context. But there is just as little doubt that the psychology of the situation was widely different from his conception of it ; there was no simple sequence of thought upon thought, idea upon idea. Let the reader observe for him- self! We shall not here enter upon the question of classification. The § III. The Associative Consciousness 391 various authors who have drawn up tables of associations have based their arrangement, almost without exception, upon logical principles, upon the meaning of the associated ideas ; they have referred the associations to certain logical categories, such as subordination, coordination, cause and eifect, means and end. The results may be of value for a psychology of individual differences ; they have no place in a general, descriptive psychology. Moreover, associa- tions vary with circumstances. It has been found, under experi- mental conditions, where a stimulus- word is given and the observer has to reply at once by naming the first word which occurs to him, that substantives are associated to substantives, adjectives to adjectives, numbers to numbers ; and that the association is nearly always formed within a single sense-department, so that red calls up green, and hard, soft. But if the conditions are changed, and a little more time is allowed the observer, the character of the asso- ciated ideas is also radically changed. Fatigue, again, may bring out purely mechanical associations (snow — ball, fish — dish) which are ordinarily foreign to the observer's consciousness. Introspective Analysis. — If a familiar visual stimulus (word, simple picture) is presented to • the observer, with the instruction that he shall receive it passively and report the consequent course of his mental processes, the following results appear. First, there is a simultaneous association of stimulus and internal speech ; the word or the pictured object is named. Thereupon follows an associative complex, which may assume any one of three principal forms. ( i) The stimulus arouses, either at once or very shortly after the named perception has become clear in consciousness, and either as a whole or by way of some part or aspect, an affective process, a feeling in the widest sense (p. 228). The feeling, in turn, calls forth an associated idea, which may subsist for a time alongside of the original perception, but soon replaces it. Thus, a word printed in very small letters upon a large ground aroused the feeling of loneliness ; a word printed in red, the feeling of ex- citement ; the word ' blinding,' the feeling of a blinding light; and then the feeling itself (or, in the author's view, the kinaesthetic and other organic components of the feeling) brought up an idea which supplanted the meaning of the stimulus-word. (2) In other cases 392 Association the named perception is either supplemented or replaced by the idea of some object or picture previously seen. Thus, an outline drawing of a face may suggest the idea of a friend, whose features are then, so to speak, read into the drawing ; the perception is lost or merged in a simultaneous association. Or the word ' Tell,' printed on a blue ground, calls up a familiar picture of William Tell springing from a boat to the rocks ; the blue of the background becomes the blue sky of the painting. There are many intermediate forms between these extremes, as there are also between this group of associations and the next. (3) Here the stimulus arouses an idea which, at first thought, appears to be separate and detached ; we have the traditional pattern of the successive association. And, occasionally, we cannot go behind that pattern ; the named per- ception and the idea seem to be mechanically linked ; we are in presence of the limiting case. Usually, however, introspection takes us farther. Thus, the outline drawing of a tent called forth the idea of a certain city market ; and for a moment the observer could simply report the bare succession of the experiences. But then he found the cue : he had ridden through the market, on his bicycle, in much the same attitude in which he now sat ; a massive complex of organic sensations was common to the two situations. — Observations of this sort make it quite clear that the type of associa- tion is the simultaneous association, and that successive asso- ciations — to put the matter a little paradoxically — are simply simultaneous associations drawn out in time. If we keep strictly to the observed facts, we can find no psychological difference between the idea and the association of ideas. Still, the practical difference remains that our ideas come ready-made, whereas we can establish new associations. May not introspection show the con- scious mechanism of this novel grouping .■■ and may we not thus get fresh light on the nature of the mixed per- ception, and of the idea itself .' Wundt has answered these questions in the affirmative. He believes that associations are always established in the §111. The Associative Consciousness 393 same way, and that the machinery can be laid bare by experiment. All association, he says, is connection of elementary processes ; the phrase ' association of ideas,' if it means that the ideas connect as such, is a misnomer. And the connection of elements is itself a twofold process. When a perception or idea is effective for association, its elements first arouse images that are like themselves ; there is a fusion of like with like. But the terms of this fusion have been together, in former conscious presents, with other, unlike elements ; the fusion is, therefore, at once supplemented ; the homogeneous nucleus is surrounded by all sorts of connected processes. If the association is simultaneous, this is a full account of the matter. If it is successive, then some element in the cluster of associates about the original nucleus arouses its like; a new fusion is formed ; and so the process is repeated. Wundt's first proposition, that only the elementary components of perception and idea can enter into associative connection, is based partly upon the nature of the idea, and partly upon facts of observation. The idea is fluid, variable, instable ; it does not stand still to be connected ; it has no solidity, so to say, that should allow it to be coupled with another, equally solid idea. And if we observe associations under experimental conditions, we find that they hinge, in reality, not upon the ideas as wholes, but upon some simple constituent of the ideas. This point established, we may go on to the mode of elementary connection. The first stage, the fusion of like with like, be- comes clear if we translate it into physiological terms. When a complex stimulus is presented to the organism, it arouses a com- plex excitation in the brain. But some at least of the component stimuli have impressed the brain in the past. These stimuli, then, running into the paths of previous impression, reexcite a previous brain-activity; the other, new stimuli have to make their im- pression for themselves. Now, if we retranslate, we have the 394 Association conscious fact of fusion. The incoming sensation or image, if it has been in consciousness before, — and otherwise it could not be effective for association, — blends with its own image, with its rearoused self. Since the terms of this fusion are qualitatively alike, the conscious resultant is merely the element itself, given at increased intensity and with a high degree of clearness; we know, Wundt says, that the familiar elements in a complex situation stand out strongly and clearly, while the unfamiliar elements are weaker and more obscure ; here, then, is evidence of the nuclear fusion. * The second stage presents no difficulty. The reinforced central element, just because it has been in con- sciousness before, and is therefore fitted to arouse the nuclear fusion, must also stand in connection with many other elementary processes ; and it is merely a matter of circumstances which of these shall actually be evoked. What is to be said of this analysis? First, that it is by no means to be confused with the traditional doctrine of association. Wundt's fusion of like with like is not association by similarity ; and his cluster of associates is not association by contiguity. Every case of associates, whether ' by similarity ' or ' by conti- guity,' involves, according to Wundt, both of the elementary con- nections : the rearousal of the like and its supplementing by the unlike. Secondly, that the analysis is, as it professes to be, an analysis of observed occurrence ; it differs from the older ' laws of association,' not only in form and content, but also in derivation ; it is not a product of logic, of reflection. The author offers only two criticisms. The one is, that Wundt has placed the whole mechanism of association in the realm of consciousness, whereas there seems to be no question that, in many instances, the mech- anism or a good part of it is purely physiological, and finds no conscious representation at all. And the other is, that the fusion of the incoming process with its imaginal twin, while as an hypoth- esis it is adequate to the facts, is nevertheless not directly attested by introspection. We might, perhaps, speak of a reinstatement of the like, rather than of a fusion of like with like ; the concur- rence of the present excitation with the preexisting impressional tendency would then be a physiological process, to which the References for Further Reading 395 emergence of the single element, strong and clear, would directly correspond ; there would be no rearousal of the mental double. The law of association (§ 107) will now operate as follows. Two nonsense syllables, let us say, are given within the same con- scious present. Later, the one of them is presented alone. The single syllable, or that aspect of it (visual, auditory, kinaesthetic) which was prominent in consciousness at the time of its earlier presentation, reinstates itself; the previous impression of the nervous system makes the path of excitation easy, and the per- ception is clear and intensive. Along with reinstatement comes associative supplementing : the other syllable appears in imaginal form. So we have what appears to be a typical case of ' associa- tion by contiguity ' ; but we also see the danger (p. 380) of identi- fying the traditional law of contiguity with our own general law of association. A final word of caution ! We have spoken of impression, and of associative tendency, as if these things were real physiological characters. So, in one sense, they are : the nervous system behaves in certain definite ways which we are in duty bound to rec- ognise and to name. But it must be remembered that our know- ledge is altogether indirect, drawn from the results of psychological experiments. What the impression and what the associative ten- dency are, in themselves, — what goes on in the nervous system when a stimulus is impressed and an associative tendency estab- lished, — of all this we know nothing. The physiological explana- tion of association is, therefore, a problem for the future. References for Further Reading §§ 105-111. H. Ebbinghaus, Ueber das Gedachtnis, 1885; Psychol- ogies i., 1905, 633 ff. ; E. Claparfede, L'association des idies, 1903 ; W. Wundt, Physiol. Psychol., iii., 1903, 518 if. For experimental methods, C. S. Myers, A Text-book of Experimental Psychology, 1909, 144 fF. Discussions of association which have permanent value, but which the authors would probably modify if they were writing to-day, will be found in W. James, Principles of Psychol., i., i8go, 550 fF. ; O. Kiilpe, Outlines of Psychol., [1893] 1909, 169 fF. MEMORY AND IMAGINATION § 112. Retention: the Course of the Image. — An impres- sion made upon a plastic substance persists, for some length of time, after the removal of the impressing object; the substance retains the impression. Suppose, then, that a stimulus has impressed the brain : the nervous substance will retain this impression after the stimulus has ceased to act. The sensation or perception will be followed by an image or idea which — if nothing interferes with it — will remain in consciousness so long as Jheimpression retains a.c ertain dep th. What happens to it in the meanwhile, during the gradual obliteration of the impression ? The question is not easy to answer. We saw in § 60 that every stimulus of moderate intensity arouses a wide- spread reaction; and it is equally true that every image, auditory or visual or what not, appears in a complex mental setti ng. When we are dealing with sensation, our organic attitude is determined and maintained by the stim- ulus, which further serves to guide and correct our asso- ciations ; consciousness is in relatively stable equilibrium. But, when we are dealing with image, the organic attitude is likely to vary, and the associations, being of the same mental stuff as the image, are likely to influence it in vari- ous ways. Besides, the course of an image can hardly be followed, even under the most favourable experimental conditions, for any length of time. Some new impression is sure to stamp out the old, or some new stimulus to re- arouse the preexisting tendencies of the part of the brain im- pressed, and the image is thus cut across and interfered with. 396 § 112. Retention: The Course of the Image 397 However, if we put together the results of investigations so far made, we may say that an image or image-complex is subject to three distinguishable modes of change : it may die awa y, i t may app ro ach a ty pe, or it mav be incor po- rated, wh ol e or p ar t, in new imag i nal formati ons. We often read of the fading and decaying of images, though we do not so often find a description of the process. If we consider the attributes of the image, it seems that those which suffer directly by lapse of time are intensity and dur ation ; loud images become faint, bright images (p. 204) become dull, and all images flit through consciousness the more hurriedly, the farther back the original experiences lie. These are intrinsic changes, due to the weakening\of the nervous impression. Other factors, however, are at work. Thus the quality of the visual image is definitely affected by the nature of the objective illumination to which the retina is subjected : images of colours and greys tend to lighten in the light and to darken in the dark. Tonal images tend to flat, possibly because the accompanying kin- aesthetic image of laryngeal adjustment tends to weaken. More important is the gradual shift from individual quality to regional or type quality. We saw in § 107 that an association may be aroused, not only by the recurrence of a familiar idea, but also by the occurrence of a novel but similar idea ; the nervous conditions of like ideas are partially the same. It appears, now, that the nervous conditions of neighbouring sensory qualities are in part the same, or at least that the impression of any one subarouses the impressions of the others. For, if a particular colour or tone is impressed, the observer soon grows doubtful of its identity ; when he seeks to call it up, he may image a quality that lies at some little distance from it on the scale of colours or tones ; when a slightly different colour or tone is presented, he may be misled by his image into pronouncing it the same. The image is, of course, always an individual quality, but its quality is no longer strictly correlated with that of the primary sensation. The same result may be brought about, indirectly, by verbal 398 Memory and Imagination association. We may remember a colour as red, a light as dark grey, a tone as high. If we then try, at some later time, to image the colour or the light or the tone, we may image that special quality which, under the conditions of the moment, is the nearest representative of the class red, dark grey, high ; that is, the qual- ity whose image is ' readiest,' most easily evoked by the associa- tive tendencies of the verbal idea. In such cases we may travel very far from the proper image of the primary sensation. Or, again, we may remember the original quality by absolute impres- sion (p. 313). As our experience grows, we form in all depart- ments ideas like the composite and standardised idea of space to which we referred in § 89 ; and these ideas may, like that, lapse into unconsciousness and be replaced by a cortical set, or may show only as total conscious attitudes, or may be represented on the particular occasion in some partial and fragmentary way. On its spatial side, e.g., the image is mainly determined by absolute impression, so that small extensions become still smaller, and large still larger, in the corresponding images. The same influence may be traced in the case of intensity ^ and duration. So with quality : if the colour strikes us as a beautiful red, the light as an unusually dark grey, the tone as excruciatingly high, we shall be likely, later on, to confuse the imaged qualities with those of other, similarly impressive stimuli. ^ The attribute of intensity has often been denied to the image. "The idea of the brightest radiance does not shine, that of the intensest noise does not sound" (H. Lotze, Outlines of Psychology, tr. 1886, 28); "the ideas of the slightest rustling and of the loudest thunder exhibit no difference in intensity whatever" (T. Ziehen, Inirod. to Physiol. Psychol.,\x. 1895, 154). The author believes that such statements betray a form of the stimulus-error (p. 218). At all events, there is no doubt — since the experimental evidence is positive ■ — that images have intensity. If now the image of the thunder is of long standing, and the image of rustling is recent; and if the underlying nervous impressions are allovi'ed to fade out undisturbed; then there may come a time when the intensities are equally weak. Only under these exceptional condi- tions, however, can Ziehen's remark be true. And, as a rule, the image of thunder will always, whatever its age, be stronger than the image of rustling, because thunder makes on us the absolute impression of a typically loud sound, and rustling that of a typically faint, stealthy sound. § 112. Retention : 'The Course of the Image 399 We have spoken of ' remembering ' the original colour or tone by means of the class-name and the absolute impression. A dis- cussion of the memory consciousness is not yet in place. Notice, however, that in this process of remembering the image may have disappeared altogether; it is only by accident that it can recur; in the great majority of cases it has been ousted by another image. Most images, indeed, are not allowed to live out their lives ; the incoming stimuli and the preexisting tendencies of the nervous system are too much for them. Instructive observations on the career of imaginal complexes may be made as follows. The observer draws on paper, from a copy or an object, some fairly simple figure : a fleur-de-lys, an heraldic animal. A week later, he is asked to repeat his drawing from the image of the previous drawing ; a week later the same request is made, and so on. It is found that certain features of the image may disappear entirely, and that oftentimes the re- peated figure tends to approach a schematic type; these results are already familiar to us. It is also found, however, that the fig- ure may be transformed : certain principal lines of the original drop out, while certain secondary lines form associations of their own, and become dominant ; so that, in course of time, the fleur- de-lys has changed, e.g., into a Greek cross. The method does not permit of detailed interpretation, but it shows that an image may persist, unsuspected, in consciousness, through incorporation in a number of successive ideas. The Memory After-image. — Most observers find no difficulty in passing directly — that is, after a very brief interval (p. 298) — from sensation to image ; even in the case of vision, conditions may be arranged which prevent interference by after-images (pp. 68, 72). Sometimes, however, the sensatio n is followed bv a process, lasting perhaps from 5 to 10 sec, which F echner fRilpH tVip mpmnry after-image. This is not an after-image proper : for it depends, as the image does but the after-image does not, upon the clearness of the primary sensa tion ; it appears only if, like an image, it is sought for, j^a lled u p ; it is stronger and clearer after a brief observation, while the after-image is better when stim ulation is pro- longed ; and it_repp.its the li ghts and colours of the ori ginal at a 400 Memory and Imagination time when the after-image, were it present, would be complement- [ ary. The memory after-image is, in fact, a sort of instantaneous photograph of the sensation or perception. It is reported by observers who have a very poor general furniture of visual imagery, and doubtless plays a larger part in the imageless than in the imaginal mind (§ 141) ; but many minds of the latter type possess it. We shall attempt an explanation later (§ 118). The Perseverative Tendency, — Tma ges themselves seem, a t times, to crop_up_ofiheiL03En>accord ; we are haunted by tunes, by tags of verse, by a picture, by the face of a drowned man ; and ideas occur to us in the most incongruous way. Experiments on verbal association (pp. 274 f.) show the same phenomenon; the ob- server will repeat a word again and again, in his series of responses, without realising that he is obsessed by this particular associate. Grouping all these facts together, certain psychologists have con- cluded that the brain is the seat of what they term perseverative tendencies. The impression does not fade out steadily, but re- covers itself, so to speak, from time to time and under favourable conditions, so that the idea may surge back spontaneously into consciousness. If this hypothesis is correct, we have to distinguish three sets of nervous tendencies. First, we have t he impressiona l— tendency, which represents the ' readiness ' of an idea to emerge, the dis- tance below the conscious limeh at which its excitatory process is now going on. Secondly, we havp t-Vif; ai;<;nHat-ivp.±&»dpnry, which represents the strength of the connection between one impression and another, or the degree of excitation that will accrue to the one when the other is reexcited. Thirdly, we have the perse verative tendency, which is a sort of rhythm imposed on the impressional tendency, such that the idea does, now and again, emerge with- out the aid of the associative tendencies. Why, then, should we separate impressional and perseverative tendency? Why should we not say, at once, that the impressional tendency varies, oscillates, fluctuates? Because the status of the impressional tendency, as we have defined it, is fairly well assured, where as the status of the perseventive tendencg -is doubtful. All these hauntings and recurrences may, in fact, be accounted for in § 113. Retention: The Process of Dissociation 401 one or other of the three ways outlined on p. 386, and accounted for more satisfactorily than on the assumption of perseverative ten- dency. Perseveration is strongest under two, somewhat contradic- tory conditions : i mmedi ately aft er the original perceptio n, and during the onset of fatigue . In the former event, both the im- pressional and associative tendencies will be strong, so that there is little to choose between the alternative explanations. But in the second case, of fatigue, it is not easy to see how the perseverative tendency should be set in operation, whereas it is natural that the more ingrained, more permanent associative tendencies should alone remain active, and that the range of consciousness should thus be restricted. There is, then, no harm in keeping the terms ' perseveration ' and ' perseverative tendency' to designate a certain mode of behaviour of images and a certain part-problem of nervous retention. But there is, in the author's opinion, no positive evidence that the behaviour is unique, or the problem insoluble by appeal to impres- sional and associative tendencies. § 113. Retention: The Process of Dissociation. — The as- sociation, like the image, is retained for a time ; the associ- ative tendencies persist along with the impressions. But an association, if left to itself, soon begins to break up ; the associative tendencies weaken, at first quickly, then more and more slowly, until finally they cease, so far as conscious- ness is concerned, to act at all. It is possible, by means of nonsense syllables, to trace out this process of dissociation, and it is also possible to determine, by variation of the experimental conditions, what are the principal influences that make for permanent retention. The use of nonsense syllables permits us to follow the associa- tive tendencies from their first establishment to their final decay ; there is practically no danger of reinforcement or of inhibition in the intervals of the experiment. It seems certain that these limited and clean-cut tendencies do, in time, disappear ; they die 402 Memory and Imagination of old age. The much more complicated tendencies established by meaningful material seem, on the other hand, to persist, below the limen of consciousness, for very long periods, possibly throughout the individual life. We learn poems, in childhood, which we may never think of again until we find our own chil- dren learning them twenty or thirty years later. We try our memory, and discover that, except for a tag here and a tag there, we have forgotten everything. Nevertheless, if we sit down to memorise one of these old poems and another, new poem of the same length, the same metrical form, and the same level of imagination, we regain the old with considerably fewer readings than must be given to the new ; the associative tendencies were there, in subliminal degree, although the associations had long since vanished. Childhood, of course, is a plastic period ; the original impressions were deep, and the original associations were little interfered with. But even if the experiment is transferred to adult life, the associative tendencies show an extraordinary per- sistence. Ebbinghaus learned some stanzas of Byron's " Don Juan " in his thirty-sixth year, and did not look at them again for twenty-two years. He had completely forgotten them, but he found evidence that the associative tendencies had not died out. It has been shown, by the experiments with nonsense syllables, that, if two associative tendencies are of the same strength but of different ages, a repetition of the association has the greater value for the older-established tendencies. Hence the advantage of distributing in time the readings of the material to be memorised (§ 109) ; the associations that are strengthened by the successive readings are older than they would be were the readings massed together. The explanation appears to be as follows. Remote and retroactive associations disappear more quickly than direct associations. The successive readings will therefore sustain and reinforce the direct associations, while they may have actually to reestablish the others ; the benefit of the readings will fall mainly to the direct associations. Distribution in time thus plays directly into the hands of the law of initial inhibition. Contrariwise, the massing of the readings will keep the secondary associations alive, and in so far will delay the action of the law. § 114- Retention: Individual Differences 403 § 114. Retention: Individual Differences. — The image is a later development than the sensation, and we may ex- pect, accordingly, that it will show a greater individual variation. The psychology of sensation is concerned primarily with uniformities ; all those who possess normal sense-organs have the same general endowment of sensa- tions ; and we refer striking peculiarities like colour-blind- ness, tone deafness, insensitivity to pitch differences, — we refer these peculiarities, when they appear, to some abnor- mality of the organ. The psychology of the image, on the other hand, is essentially an individual psychology. The normal brain is a much more variable thing than the normal sense-organ, and the ideas of different minds are constituted in very different ways. Attempts have been made to reduce these differences to order, and to classify observers in terms of their imagi- nal type. Four principal modes of ideation have thus been distinguished : the visua l, the__auditoryJiinaesthetic, the kinaesthetiCj_and t he mixed . The visually minded ob- server, for instance, retains his experiences in terms of vis- ual imagery ; his perceptions, of whatever kind, are trans- It ^ted into visu_a LJdeas. An observer of the mixed type repeats i n image what he has received in sensat ion, though Vip_wi11 prnbaVily Jhave a Certain leaning towa rds-a particu- 1ar_Ha«g__of imagpg. It seems that there is no pure audi- tory type, and no visual-kin aesthetic type ; at any rate, these cases are exceptional. Words are retained in simi- larly characteristic forms : as visual, and as auditory-kinaes- thetic images. It is probable, again, that the auditory- kinaesthetic elements do not occur separately, although the emphasis may be preponderantly upon the one or the other. 404 Memory and Imagination While, however, these gross differences undoubtedly ex- ist, generalisation must not be pushed too far. Thus, we cannot argue from verbal to total type ; a man may image words as auditory-kinaesthetic, and yet be, on the whole, visually minded. Indeed, it may be questioned whether, apart from the mixed mode of imagery, a total type can be said to exist at all ; the imagery of a given observer will vary both with the manner of presentation of the original material, and with the purpose or intention with which the material is approached. We might, perhaps, sum up the situation by saying that individuals are predisposed for different kinds of imagery ; that, as a rule, the predispo- sition represents a line of naturally least resistance, but does not prevent the opening of other lines (by the nature of the stimulus, by special cortical set) ; and that, in certain cases, the predisposition is exclusive and supreme. We made a brief reference to imaginal type on p. 199. The subject is, evidently, of great importance for education as well as for psychology ; it has therefore received much attention, and many methods for the determination of type have been devised and applied. The principal result of the investigations is the proof that type is far more variable and more complex than had at first been supposed. Two points, in particular, may here be mentioned. The first is that the presence of imagery does not necessarily imply the use of imagery ; my mind may be full, e.g., of visual images, and yet I may habitually mean and under- stand, think and remember, in other than visual terms. And the second is that a man's talent, or his choice of a profession, is no indication of his imaginal type. " I should have thought," re- marks Gallon, " that the faculty [of visualisation] would be com- mon among geometricians, but many of the highest seem able somehow to get on without much of it." " I am myself a good draughtsman," says James, " and have a very lively interest in pictures; statues, architecture, and decoration. But I am an ex- § 114- Retention: Individual Differences 405 tremely poor visualiser " ; and Galton tells us that " men who de- clare themselves entirely deficient in the power of seeing mental pictures can become painters " of acknowledged rank. The author knows a musician who has no tonal images whatever ; ask him to go to the piano and play a certain composition, and he will do so ; ask him if he can imagine what he is going to play, and he will reply, ' No ! but I am going to play it.' On the other hand, the author himself, who is no musician, is rarely if ever free from musical imagery. While these cautions are in place, it should be added that the trend of imaginal type shows itself in various, fairly obvious ways. The attitude of attention is different, according as one is visual or auditory-kinaesthetic ; and the mode of recitation differs, being slow and systematic in the former case, quick and impulsive in the latter, while the mistakes made are in both instances characteristic. A preponderant type may be traced in an author's style ; and it has been suggested that the cardinal doctrines of the traditional British psychology (§ 105) are to be explained by the fact, evident from their books, that the writers were predominantly visual- minded. There are also marked individual differences of associa- tion. Observers in the psychological laboratory fall, as do children in the schoolroom, into two great groups : the quick learners and the slow learners. Popular psychology has been all on the side of the slow pupil ; if he is slow, he is also sure ; his knowledge is solidly established ; while his more active-minded companion is pronounced shallow ; his knowledge goes as easily as it comes. Retention, we have no need to insist, is a very complicated matter, and there may very well be conditions under which popular psychol- ogy is right. Experiments seem to show, however, that at least under certain circumstances it is definitely wrong. The quick learner appears to retain as well as the slow ; he has the advantage at the start, and he loses nothing by lapse of time. 4o6 Memory and Imagination The results of these experiments throw some light on the nature of cramming, which has for the most part been roundly condemned by educators. Against cramming it may be urged that the hasty impression of a mass of heterogeneous material cannot be lasting ; the law of retroactive inhibition will come into play, to weaken the associative tendencies. The student who crams trusts to recency of experience to carry him through ; he hopes that a certain amount of his reading will cling to him just for the day or two that he needs it. " Speedy oblivion," says James, " is the almost inevitable fate of all that is committed to rhemory in this simple way." Even so, one might rejoin that speedy oblivion is not in itself a disadvantage ; a good deal that we are obliged to learn at school is better forgotten. But, that aside, the argument against cram- ming misses the point that there are two kinds of cramming, a good as well as a bad. If we wish to remember, we must submit to the laws of memory ; and bad cramming simply ignores those laws. Good cramming, on the other hand, is a very valuable asset of the quick learner. It is " the rapid acquisition of a series of facts, the vigorous getting up of a case, in order to exhibit well- trained powers of comprehension" ;^ it is precisely the thing that the lawyer, the lecturer, the teacher, the politician, the adminis- trator find necessary to success. Moreover, good cramming is itself of two kinds : we may cram with intent to remember, and we may cram with intent to forget. Both forms are useful, e.g., to the teacher : the one provides him with the expert's knowledge of the details of his subject ; the other prevents his teaching from becoming cut and dried. As with cramming, so with skimming : it is generally repro- bated. Yet it is surprising how accurate a knowledge may be acquired by hurried, selective reading, if only one has had sufficient practice. The predisposition to quick learning must, of course, be present. What that is, in physiological terms, we do not know ; but it is, at any rate, a gift, like mathematical ability or a singing voice, and should be utilised rather than disparaged. 1 W. S. Jevons, Cram, in Mind, O. S. ii., 1877, '93 ^- § 115. The Recognitive Consciousness 407 § 115. The Recognitive Consciousness. — Suppose that you are entering a street-car. As you enter, you run your eyes over the line of faces before you. The first half dozen of your fellow-passengers are strangers ; their faces arouse no interest, do not arrest your gaze. At the end of the car, however, you see someone whom you know ; you recognise him. A sudden change occurs in consciousness : you call him by name, take a seat at his side; and begin to converse with him. What was it, now, that happened in consciousness at the moment of recognition 1 What are the conscious pro- cesses involved in recognising 1 To answer these questions we must recur to facts that we already know. The first is the fact that every sensory stim ulus of moderate intensity arouses a widespread organic reaction (§ 60); an illustration is given on p. 194. The se cond is the fact that the organism not onlv sens es, but also feels ; sensory stimuli do more than arouse the sensation and the associative and organic reaction ; they set up feel-< ings as well (§ 68). These secondary effects of stimulation give us the key to the psychology of recognition. The re- peated stimulus is felt otherwise than the novel stimulus, and the feeling of familiarity, as we may call it, is the essen- tial factor in recognising ; whenever it appears, we recog- nise ; where it does not appear, we fail to recognise. The se nsatl oas and ideas of th e associative a nd organie-peac- tion then serve to make the recognition definite ; the per- ception comes to us, not merely as familiar, but with the es- pecial familiarity of a named, placed, and dated experience. The reaction set up by a stimulus consists in part of associated ideas, in part of kinaesthetic and Other organic complexes. It is tempting to suppose that the associated ideas help to constitute recognition. They may, indeed, as we shall see in a moment, be 408 Memory and Imagination the means to recognition ; and some of them — more particularly the direct verbal associate, the name — seem oftentimes to be bound up with the actual process of recognising. Nevertheless, the experimental evidence is against them. Recognition is possible jn the absence of any associated idea whatsoever ; and a perception may call up objectively correct associates and still not be recognised. In the case of the organic complexes, decision is more difficult. We have introspective warrant for believing that they enable us to recognise the perception as that special perception. Whether they enter into the process of recognising is difficult to say, be- cause they blend with the organic complexes comprised in the feeling of familiarity. So far as it goes, the evidence is also against them ; recognition, as such, seems to be wholly a matter of the feeling. What, then, is this feeling ? In experiments upon recognition it is variously reported as a glow of warmth, a sense of ownership, a feeling of intimacy, a sense of being at home, a feeling of ease, a comfortable feeling. It is a feeling in the narrower sense (p. 228), pleasurable in its affective quality, diffusively organic in its sensory character. That is all that analysis can tell us at at it. If we allow ourselves to speculate, we may go furtl r, and find a genetic sanction for its peculiar warmth and diffusion; we may suppose that it is a weakened survival of the emotion of relief, of fear unfulfilled. To an animal so defenceless as was primitive man, the strange must always have been cause for anxiety ; ' fear ' is, by its etymology, the emotion of the ' farer,' of the traveller away from home. The bodily attitude which ex- presses recognition is, on this view, still the attitude of rehef from tension, of ease and confidence.' 1 Speculations of this sort are permissible in psychology, but must be ad- mitted only very cautiously into one's psychological thinking ; their value de- pends partly upon their explanatory power, partly upon their agreement with what we know, or on other grounds can infer, of the nature of primitive mind; they are always speculations. It is clear that they involve the great question of biological heredity, into which it is here impossible to enter. The author can do no more than point out that they do not necessarily involve the direct transmission of mind, or of mental traits, from generation to generation; still less, the transmission of acquired characters. § IIS. 1^^^ Recognitive Consciousness 409 It must be added that some psychologists refuse to recognise the feeling of familiarity as a feeling, and regard it rather as a form of combination (§ 104), an ultimate and underivable mental character ; they speak of it as the quality of familiarity. There are, indeed, border-line experiences between recognition proper and direct apprehension (which we discuss below), where analysis is well-nigh impossible. But the author has read many thousands of introspective reports upon recognition, and has never yet found an observer to whom the feeling of familiarity appealed as unana- lysable. Definite and Indefinite Recogniti on. — Recognition appears in two typical forms, which nevertheless grade into each other through various intermediate stages. It is indefinite when the feeling of familiarity comes up alone ; when, e.g., we pass some one in the street, and say to our companion, 'I'm sure I know that face ! ' Somewhat more definite are the cases of recogni- tion in which the feeling of familiarity expresses itself by a general classificatory term. As we glance down the line of strangers in the street-car, we may think to ourselves, ' Doctor, — farmer, — commercial traveller.' Lastly, recognition may be definite : the reinstatement of the organic reaction, or the arousal of a group of associated ideas, or both of these supplements together, may refer the present experience, unequivocally, to an incident of the past. In the gross recognitions of everyday life there is usually some constellation of associated ideas that is evoked by the perception ; in the recognitions of the laboratory, the recurrence of the organic reaction makes the stimulus — as the reports phrase it — 'stand out,' makes it ' easy to grasp,' gives it a direct ' appeal ' to con- sciousness ; it is then identified as the stimulus that was presented before. Direct a nd Tn/i!rfct jiecof^nitio n. — When we classify recognitions as definite and indefinite, we are thinking of them as already completed. If we look at their temporal course, the way in which they are effected, we get a new ground of .classification. Recog- nition is direct or immediate when the perception at once, of itself, calls up the recognitive feeling. Recognition is indirect or mediate when the feeling attaches, not directly to the perception. 4IO Memory and Imagination but to some associate of the perception. We pass a stranger on the street ; but we are suddenly hailed by a familiar voice, and the stranger is himself recognised as an old friend. We try to find our host's face in a group-photograph of schoolboys, and we are wholly puzzled to identify him. The face is pointed out, and recognition follows ; the photograph grows more and more like, the more closely we examine it. In many instances of this sort the recognitive consciousness shows a high degree of complexity. Thus, we may be quite sure that the stranger is our old friend, and yet continue to recognise nothing about him but his voice ; the feeling of familiarity alternates with the feeling of strange- ness, and the play of association becomes extremely complicated. In principle, however, the conscious mechanism of recognition is the same throughout. Lack of Recognition. — Failure to recognise is not a mere ab- sence of recognition, a conscious blank ; it is a positive expe- rience. The unfamiHar perception, like the familiar, stands out clear in the focus of consciousness, but its setting is different. It is not easy to grasp, and it makes no appeal ; it is accompanied by a feeling of strangeness, and by a general attitude of conscious- ness which we may call the attitude of search or enquiry. We may guess that the feeling of strangeness is the modern represent- ative of primitive man's anxiety in face of the unknown ; it is an uneasy restlessness, distinctly unpleasant (p. 269). The conscious attitudes will occupy us later (§ 141). § 116. Recognition and Direct Apprehension. — The ner- vous system as a whole, no less than the various sense- organs, adapts itself to repeated stimuli. Affective pro- cesses, as we know (§ 69), show this phenomenon of adaptation ; pleasantness and unpleasantness fade out into indifference. And the organic stir aroused by an affective stimulus is more and more reduced, until it disappears altogether. It is not to be expected, then, that the feeling of famil- iarity will persist unchanged, as perceptions are repeated. § ii6. Recognition and Direct Apprehension 411 We can, in fact, hardly be said to recognise the clothes that we put on every morning, or the pen with which we are accustomed to write ; we take them for granted. When famiharity has gone thus far, when the familiar has ceased to evoke an organic reaction and to be pleasant, we say that recognition has passed into direct apprehension. We have here an instance of the operation of a psychological law to which reference was made in § 103, the universal law of mental growth and decay. Just as meaning may cease to be conscious, and may be carried in purely physiological terms, so may recognition be reduced from a conscious process to an un- conscious cortical set. Between the two extremes there are, naturally, many intermediates. The feeling of familiarity, the feeling of being at home, changes first to something that is still feeling, though much weaker on the affective and much less clear upon the sensory side, — to what we may describe as an ' of course ' feeling, which is still some distance removed from sheer indifference. As time goes on, this of-course feeling itself dies out ; the affective adaptation reaches its term, and the perception fails to arouse any organic reaction. In the author's opinion, the shift from consciousness to uncon- sciousness may be complete. Some psychologists, however, be- lieve that direct apprehension always involves consciousness. We not only perceive objects by eye or ear ; we move to them, turn to them, stand or sit to them, handle them. Hence, although the feeling of familiarity has disappeared, the sight or sound will throw us into a certain bodily attitude, whose sensory or imaginal representation constitutes our apprehension of the object. That is the theory. The author's principal objection to it is that it appears to confuse recognition with meaning. The essential thing in recognition, as experiments prove, is a feeling, the feehng of familiarity ; the associated sensations arising from bodily atti- tude, from action upon the object, may help to render recognition definite, but do not constitute recognition. We can hardly argue, then, that these sensations constitute recognition (direct appre- 4.12 Memory and Imagination prehension) after the loss of the feeUng. Kinaesthetic contexts are common vehicles of meaning ; they may constitute an object a pen, or even — in a certain sense — ray pen ; they cannot con- stitute it my familiar pen. It is not difficult to make the objection concrete. An old suit of clothes goes to the cleaner, an old type- writer goes to the repairer. We say, on their return, that the clothes must be ours, because they slip on so easily, and that the machine must be ours, because we work it so readily ; but, we add, we should never have recognised them as ours. That is, the kinaesthetic complexes give them meaning, even a definite refer- ence to our own past; but they do not, of necessity, involve recognition. And if that is true, there is no reason why they should involve or constitute direct apprehension, which, by hypothesis, is the descendant of recognition. The theory implies that, when the feeling of familiarity is gone, nothing but meaning remains ; the author holds that direct apprehension is not identical with meaning. Another and more general objection is that there are many per- ceptions in which kinaesthesis is not noticeably concerned. I see the same landscape every day from my bedroom window, and I apprehend it directly as that same landscape. It is true that I look at it, turn to it ; but I look at it from many angles, with head and eyes in various positions, so that the kinaesthetic components must, at the best, be extremely variable ; and, as a matter of fact, the eye-movements are rarely conscious, and the sensations due to movements of head and body are usually incorporated in other perceptions. It seems impossible that a kinaesthetic complex can constitute my direct apprehension of the landscape. Moreover, there are cases of direct apprehension, under laboratory conditions, in which no trace of kinaesthesis can be discovered. Disturbance of Apprehension. — It is interesting to note what happens in consciousness if direct apprehension is for some reason prevented. We look at our inkstand, and find that the pen which we always keep in it has disappeared; or we glance round the breakfast room, and discover that a picture which always hangs on a certain wall is absent. We have not been in the habit of recognis- ing pen and picture ; they are too familiar. But now that they are § 117- The Memory Conscioustiess 413 gone, the situation jars upon us ; we have a feeling of helplessness or of unpleasant surprise. This observation is itself important : it shows that, when the organism has become adapted to a certain complex of stimuli, the maintenance of adaptation depends upon the persistence of the complex ; a negative change, a subtraction of stimuli, creates a new situation, to which the organism reacts as a whole. There is, however, another side to the case which is, perhaps, still more important. At the moment of conscious dis- turbance, before the unpleasant feeling has arisen, the of-course feeling springs up in unusual strength ; it is as if, for a brief space, we reverted in imagination to a recognition of the missing object. The feeling is not intensive if measured by any absolute standard, not as strong as the feeling of familiarity proper ; but it is more pronounced than in the ordinary intermediate forms that connect recognition with direct apprehension. Here, then, is opportunity for the introspection of an elusive process, the conditions of whose appearance are otherwise not easy to arrange. § 117. The Memory Consciousness. — Hitherto we have said nothing of the conscious side of memory. We have spoken of impression, associative tendency, retention, and we have spoken of image, idea, and the association of ideas ; but no image or idea is intrinsically a memory-image or a memory-idea, and no association necessarily wears the stamp of memory. An idea comes to us as remembered only if it comes to us as consciously familiar. And the mgmory consciousn ess-is. i n fact, the recognitive c onscious- ness over again , wit h the sole difference that t he focal process, t he process remembered, is an idea and not a per- ception. An irlpa_ic_a^ mpmnry if it Ts accompanied by the feelirg "f familiarit-y ; and an idea is specifically re- me mbered if it is placed an d dat ed by the organi c reaction and by associated ideas. The consciousness in which the memory-idea is set may show the pattern either of primary or of secondary atten- .14 Memory and Imagination ion (pp. 275 f.), and we speak accordingly of passive nemory or remembrance, and of active memory or recol- ection. Both types of consciousness are discursive; that s, are characterised by wandering of attention, shift of magery, variable play of association. Remembrance ihades off into day-dreaming or reverie, and thus into magination ; recollection shades off into search or enquiry, Lnd thus into thought. Between the two lies a long series )f intermediate forms. The introduction of nonsense syllables, while it led us back from ogical meaning to psychological fact, and so helped to break up lie schematism of the traditional psychology of association, has levertheless done psychology a certain disservice. It has tended ;o place the emphasis rather upon organism than upon mind ; nvestigation has been directed to the question of what the ner- vous system does rather than to that of what the memory con- iciousness is. The knowledge thus acquired is, no doubt, of high jsychological importance, and we have taken account of it in Dreceding Sections. But the definiteness of result, the fascination jf tracing the criss-cross of associative tendencies, and the possibil- ty of throwing the results into quantitative form, — these things lave forced into the background of current interest the more mmediately psychological problem of a description of the nemory consciousness. Introspective studies are comparatively "ew, and generalisation must be premature. However, something may be said. If we take, first, the pattern jf consciousness in recollection, we find what may be figuratively lescribed as a reconstruction along the line of least resistance. Thus, in trying to recall a group of meaningless visual forms, and to draw them from memory, the observer does not start out with a ready-made image. He may begin with a mere fragment of imagery, or with no imagery at all. As he begins to draw, the recognitive feeling at once appears, rejecting here and accepting there ; and it remains in consciousness to determine the whole course of recall and the nature of the final product, as well as to § 117- The Memory Consciousness 415 react upon that product when present in perceptual form. Another very prominent feature of the recollecting consciousness is the emotive attitude of expected ease or difficulty of recall; this also may intervene as soon as the first clue, such as an indefinite visual image of position, has arisen. The drawing, then, is not a repro- duction, a copy of the original perception, mediated by retention ; it is a reconstruction, a construction of a particular result that is accepted in place of the original. If the figures to be recalled are pictures of familiar objects, the gross clue to the recollection may be given by a visual image. But the details are again worked out by a process of reconstruction. The criteria of acceptance are direct recognition of an image ; relative clearness of imagery (though this is ineffective as against even a very weak recognitive feeling) ; absence of rival imagery ; and the observer's general knowledge of the objects pictured. Here, too, we are far removed from a simple reproduction. Nevertheless, the reconstruction follows the line of least nervous resistance. There is a tendency, so far as mental constitution per- mits, to recall in kind : visual perception by visual imagery, audi- tory perception by auditory imagery. Familiar verbal associations, especially names, are used as aids to recall. Familiar sounds are recalled by way of the kinaesthetic processes aroused in their imita- tion. The image tends to lose its specificity and to approach a type or mean : a voice, at first imaged in its individual timbre, is presently called up as bass or tenor only. In the recall of pictures, the observer falls into a form of the stimulus-error, and replaces the imagery of the picture by that of the object pictured. This account, fragmentary as it is, will suffice both to indicate the general character of consciousness in recollection, and to illustrate the difficulty of adequate introspection. The observer has to describe processes of extreme complexity, and will naturally turn first to what is most emphatic or to what he is most confidently ex- pecting. The field must be raked over again and yet again before we can be sure that we have gathered up the full introspective yield. Moreover, the observer has to report complexes that are hurrying through consciousness and changing as they go ; he is therefore Ukely to report in large, general terms ; he has no time 4i6 Memory and Imagination "or analysis ; he points a verbal finger at the retreating process, md therewith turns to its successor. But then every one of these, argely designated processes must be made the topic of a special inalysis ; so that a memory study may really set more problems :han it solves. There is, indeed, a vast range of work, directly in new, that still remains to be done. As regards the pattern of consciousness in remembrance, our lata are yet more scanty. There seems to be, behind the recog- aitive feeling, a general emotive attitude that holds us, so to say, :o the same objective situation, to the same empirical context. This attitude serves as conscious background for processes of extra- Drdinary instability. Attention is labile and fluid ; the focus of consciousness is occupied now by visual or other imagery, now by scraps of kinaesthesis, now by personal references, organic or t'erbal ; consciousness itself contracts and expands, pauses and hur- ries, and shows the most abrupt changes of direction. The author is- well aware that this description is both figurative and conventional. It will, however, be a long time before psychologists can offer a composite photograph of the total consciousness in re- membrance. ^' § 1 1 8. The Memory-image and the Image of Imagination. — In minds of the visual type, imaginal complexes, of the same general degree of complexity as perceptions, are of common occurrence, and may readily be aroused under experimental conditions. These complexes fall into two great groups. Some of them have a personal reference, and represent definite incidents of the observer's -past ex- perience ; others lack the personal reference, and have no associations eitherof time or of place. The former, in other words, are what would ordi narily be term.e d-memorv- iiQages ; th e latter are images, of imag ination. The two kinds of images present marked differences to introspection, but the differences are precisely the reverse of what, under the influence of popular psychology, we § ii8. Memory -image and Image of Imagination 417 might expect. Popular psychology regards the memory- im age as a stable copy of past perception, and the image of imagination as subject to kaleidoscopic change. In fact, it is the memory-image that varies, and the ima ge of i magination th at is stalile.. The observer is placed, as he prefers, in a dark room, or in the light, facing a blank wall, and is asked to report his images as they appear ; words or sentences are spoken by the experimenter, as cues for the arousal of memory and imagination. It is found that the memory-images are filmy and vaporous, that they show little or no relief and little or no diversity of light and shade, and that they are often colourless, while the images of imagination are substantial, extend into the third dimension, and are often highly coloured. The memory-images develope slowly, are liable to continual change, and last but a short time ; the images of imagi- nation present themselves at once and as wholes, change but little, if at all, and are persistent. The memory-images involve roving eye-movements and general motor restlessness ; the images of im- agination involve steady fixation and motor quiescence. Both images are accompanied by, or interfused with, kinaesthetic and other organic processes, but the character of the processes is different. Kinaesthesis comes in to fill out the gaps and blanks in the memory-image ; the observer sometimes remarks that he can't say what he sees and what he feels. This filling or supplementing is always of an imitative sort, repeating certain phases of the original experience. In imagination, on the other hand, the organic factors are empathic : ^ thus, with the image of a fish, an observer reported " cool, pleasant sensations all up my arms ; slip- pery feeling in my throat ; coolness in my eyes ; the object spreads all over me and I over it ; it is not referred to me, but I belong to it." Finally, the image of memory brings with it the pleasurable recog- nitive feeling, whereas the image of imagination is set upon a background of feeling which the observers variously describe ' Empathy (a word formed on the analogy of sympathy) is the name given to that process of humanising objects, of reading or feeling ourselves into them, which we described on p. 333. ^iS Memory and Imagination IS a feeling of strangeness, of novelty, of personal detachment, of ;reepiness, of weirdness, of unordinariness, of peculiar discomfort. The same phenomena recur with auditory and olfactory images. Auditory memory-images involve movements of the larynx, and alfactory memory-images involve twitchings of the nostrils, which ire not found with images of imagination. In both cases, the nnemory-images are less substantial than the images of imagination, ind run a different temporal course. The characteristic feelings, 3f familiarity and strangeness, appear as they do with visual images. These are the extreme forms of the imaginal complex, the typical memory-image and the typical image of imagination. There are many intermediate forms, which seem to contain both memory and imaginative elements. In particular, the imaginal complexes which represent objects in daily use, or objects of a familiar environment, appear to pass from the memory to the imaginative form ; they become stable and persistent ; but they are then wholly indifferent, felt neither as familiar nor as strange. We may regard them as corresponding, in image, to the direct apprehension of perception. The author is, indeed, disposed to believe that this observation may be generalised; that all direct apprehension, in remembrance and recollection, occurs in imagina- tive rather than in memory terms. When we solve a geometrical problem by help of a remembered figure, or of some previous re- sult, the figure or the result comes to us as a whole, clearly and substantially, almost as if it were a perception. There is here, of course, a danger of confusing fact with meaning ; of supposing that, because the meaning of the older work is clear and permanent, therefore its representation in consciousness is also stable and sub- stantial. Nevertheless, it seems to the author that the conscious stuff of most habitual memories is not that of the typical memory- image, but much more nearly resembles the material of the image of imagination. Is it not something of a paradox that the memory-image should be thus variable and instable.? At first thought, yes : because we are ready to accept, from popular psychol- § Ii8. Memory-image and Image of Imagination 419 ogy, the notion that an image is a memory-image of itself, in its own right ; and if that were the case, the image must of necessity copy or reproduce the perception. On reflec- tion, no : because the image is, after all, made into a mem- ory-image by the feeling of familiarity. So there is no reason in the world why it should copy the original experi- ence. All it has to do — ■ if we may ourselves talk a popu- lar psychology — is to mean that experience (the meaning is given as the context of associated ideas and attitude) and to be recognised as meaning it. Suppose for a moment that memory-images were just weaker copies of the earlier •perceptions, and nothing less or more : our mental life would, so far as we can imagine it, be an inextricable con- fusion of photographically accurate records. It is, in reality, because the image breaks up, because nervous impressions are telescoped, short-circuited, interchanged, suppressed, that memory, as we have memory, is at all possible. The remark has often been made that, if we did not forget, we could not remember. That is true. But we may go farther and say that, if the mental image could not decay, it could not either be the conscious vehicle of memory. On the other hand, if there is to be such a thing as im- agination, then the image of imagination must be persistent and substantial. An image is, psychologically, made into an image of imagination by the feeling of strangeness. But that the image should^simply mean ' something new ' is not enough ; it musf^ something new; it must stay to be looked at, to be described, to be expressed in artistic form; poet and painter anH" sculptor would be in sorry case if their minds were whirligigs of changing imagery. Why, then, do we not have 'the inextricable confusion of which we spoke just now .■" Because the image of imagination, ^20 Memory and Imagination Deing new, has no associations ; it stands singly at the focus Df consciousness, as objects do that we perceive for the irst time ; and if it should, presently, remind us of some- :hing, the associates will be memory-images, and not other mages of imagination. Besides, the image of imagina- [ion is not persistent in the sense of those weaker copies Df perception with which the popular psychology of mem- ary operates. In this respect, too, it resembles perception : it is persistent and substantial under its own conditions ; but if it has once gone, it must either be rebuilt, or recalled is an image *f memory. All through this chapter of psychology we see the danger of arguing from a preconceived theory, instead of appealing directly, introspectively, to mind itself. The associationist doctrine is that recognition implies the comparison of past image with present perception ; identification follows. But that is not what happens in recognition. We are taught, similarly, that the memory-image copies the original experience. It may ; but as a rule, again, it does not. We are taught that the image of imagination is a rest- less, irresponsible thing, always in the throes of dissolution and re- combination ; but it is not. We are taught that mind moves, as if on stepping-stones, from idea to idea ; once more, it does not. The contents of the preceding Sections are, indeed, a strong testi- monial to the value of the experimental method. But for that, we should still be repeating the traditional formulas. And if the Sections are scrappy, and their generalisations uncertain, this is not the fault of the method, but merely of its recency of application. Let us return to the images. It is clear, from what we have learned of the imaginal complexes in memory and imagination, that the elementary imaginal process, the image of § 6i, has two distinct forms. On the one side stands the image that may be confused with sensation. This image appears in perception, in the memory after-image, in synaesthesia, in hallucination, in the image of imagination, in habitual memories ; it moves with move- ments of the eyes, and may leave an after-image. On the other § 1 19- The Imaghtative Consciousness 421 side stands the image that is of filmier texture than sensation ; it appears in the memory-image, does not move with eye-movement, and leaves no after-image. To explain the occurrence of the two forms, we must assume either that there are two modes of cortical function, or that the stable image somehow involves sensory stimulation, while the instable image is wholly of central origin. The former of these alternatives is possible ; we know very little of the modes of cortical behaviour ; but the second appears to the author to be, on the whole, the more probable. A recent writer has suggested that the stable image is really a secondary sensation ; the stimulus which acts upon a sense-organ directly arouses its corresponding sensation ; but the excitation irradiates in the cortex, spreads to other sensory areas, and thus indirectly arouses other sensations. We have here, then, a theory which might replace the theory of.synaesthesia outlined on p. 197. It is, however, not easy to see why the secondary sensation, which itself corresponds not to a process of peripheral stimulation but to a central excita- tion, and is therefore aroused in the same manner as the instable image, should appear as sensation ; and it is especially difficult to see why it should retain the sensory character when — as in the case of habitual memories, or of certain images of imagination — there is no peripheral stimulus' of any kind. The author suggests that the sensory character of the stable image may be due to an ac- tual stimulation of the sense-organ by way of the centrifugal sen- sory conduction-paths, — though the suggestion is worth little, so long as the conditions under which these paths are thrown into function remain obscure. § 119. The Imaginative Consciousness. — A great deal has been written about the imagination; but, as a matter of fact, we know very little indeed of the imaginative conscious- ness. Most of the psychological accounts are couched in terms of some psychological theory, and most of the in- trospective descriptions published in support of theory were obtained from untrained observers and without sufficient control of the conditions of observation. 422 Memory and Imagination It seems clear that an idea comes to us as imagined only if it comes as consciously unfamiliar, with the feeling of novelty or strangeness upon it ; this feeling of strangeness is as characteristic of imagination as the feeling of famil- iarity is of memory. The consciousness in which the idea of imagination is set may then show the pattern either of primary or of secondary attention (pp. 275 f.), and we speak accordingly of passive or reproductive, and of active, creative or constructive imagination. Both types of con- sciousness are integrative rather than discursive ; the sphere of attention is limited, the play of association regulated. Creative imagination shades off into thought, and thus completes the psychological circle of p. 414. Two hypotheses of the nature of the imaginative consciousness are sharply opposed in current discussion. According to the one, the imaginative idea or constellation comes as if from without, by inspiration ; the poem sings itself, the painting groups and colours itself, to the mental ear and eye ; imagination is a native gift or endowment that finds rather than seeks expression. According to the other, the imaginative consciousness is profusely imaginal ; associations throng about the focal process; and the product of imagination is the result of choice and arrangement of these associated ideas. On the former hypothesis, the imaginatively gifted individual is the dreamer of dreams and the seer of visions ; on the latter, he is the planner, the moulder, the constructor. So imagination appears now as the typically passive and now as the typically active temperament ; precisely as genius is described now as the capacity of doing great things without effort, and now as the capacity for taking infinite pains. And witnesses can be brought on both sides. We have not the data for a final characterisation. To the author, however, the psychology of imagination takes shape somewhat as follows. Behind everything hes a cortical set, a nervous bias, perhaps inherited and permanent, perhaps acquired and temporary. § 119- The Imaginative Consciousness 423 This background may not appear in consciousness at all ; or it may appear as a vague, conscious attitude (passive imagination), or again as a more or less definite plan, aim, ambition, intention (active imagination). Whether conscious or not, the nervous dis- position determines the course of consciousness. It also helps to initiate the imaginative complex, the first concrete clue to which usually comes, in fact, as an inspiration, a happy thought : some external situation, or some group of associative tendencies that is active at the moment, touches off the disposition, and the initial idea flashes into consciousness. Whether the idea is crude or complete, and whether the following consciousness is narrow or broad, concentrated or richly imaginal, these things depend al- together upon circumstances. If we are dealing with active imag- ination, the subsequent stage, in which the idea is worked up and worked over, — while, no doubt, it may be relieved here and there by other happy thoughts, — is essentially a stage of skilled labour, of secondary attention, that ends only with the expression of the idea in objective terms. Meanwhile, consciousness has been variously emotive. The imaginative ideas bring with them the feeling of strangeness. But just as the pleasantness of recognition miy be lost in the stronger unpleasantness of the recognised object, so may the strangeness of imagination be lost in the pleasure of success, or merged in the stronger unpleasantness of failure ; and these feelings may themselves alternate, so that consciousness swings between the poles of affective experience. Meanwhile, also, all sorts of empathic complexes have formed about the focal pro- cesses, vivifying and personalising the partial products of the construc- tive effort. Whatever happens, the total consciousness is directed and regulated by the underlying nervous disposition. In memory, the observer is always within a certain universe of discourse ; there are limits, set by the fixity of the past occurrence, which he may not transgress; but within this breadth of context he can move at will; consciousness is discursive. In imagination, consciousness proceeds, as a whole, from the fountain-head of disposition ; there are no limits of any kind, save those of individual capacity and experience ; but the stream, whatever its volume, flows always in a determinate direction ; consciousness, as we have said, is integrative. 424 Memory and Imagination But what are the focal processes? One is tempted to sa)', off- hand, — images. And the answer is probably correct, if one may define the term • image.' Oftentimes, of course, there are images in the literal sense, visual, auditory-kinaesthetic, kinaesthetic. Often- times there are verbal images. But the name must also be ex- tended to processes that merely symbolise perceptual experience, and are no more like perception than the printed report of an operatic performance is like the performance. When we trace the images of imagination beyond the stage of perceptual complexity (§ ii8), we find that they undergo translation and reduction : translation out of one sense-department, along the line of least nervous resist- ance, into another ; and reduction from explicit representation to symbolism. Reduction does not mean approximation to a type; what takes place is that a mere schema, or part-aspect, or fragment of the complex comes to do shorthand service for the whole. This seems to be the truth in the text-book statements that the images of imagination tend to grow vague, general, abstract, to become shadows of their original selves. They never grow vague, in the ordinary sense of the word ; on the contrary, all of them, images proper, words, and reductions, are sensory in their reality and sub- stantialness j that is a point that we have already emphasised, and that we must by no means lose sight of; but they do become simple and conventionalised, they do tend to symbolise rather than to represent. — The reader may be reminded that this account is tentative, and far outruns the experimental data. It has the merit of reconciling the two hypotheses mentioned at the outset, and it accords with such introspective observations as we have. It may, however, be very seriously modified by future investigation. § 1 20. niusions of Becognition and Memory. — Illusory memories and recognitions are of two kinds. We may re- member or recognise something which is really, objectively unfamiliar to us, and we may fail to recognise or remember something which once formed part of our experience. Both types of illusion are quite common. § I20. Illusions of Recognition and Memory 425 Most persons, perhaps, have had occasional experience of what is called paramnesia or false recognition, a ' feeling that all this has happened before,' which persists for a few seconds in spite of the knowledge that the experience is novel. Various explanations have been offered of the phenomenon. It occurs most frequently after periods of emotional stress, or in the state of extreme mental fatigue ; that is, at a time when the associative tendencies are abnormally weak. And it seems to depend, essentially, upon a disjunction of processes that are normally held together in a conscious present. Suppose the following case : you are about to cross a crowded street, and you take a hasty glance in both directions, to make sure of a safe passage. Now your attention is caught, for a moment, by the contents of a shop window ; and you pause, though only for a moment, to survey the window before you actually cross the street. Paramnesia would then appear as the feeling that you had already crossed; the preliminary glance, which naturally connects with the crossing in a single, total experience, is disjoined from the crossing, through the abnormal weakness of the associative ten- dencies, and comes to consciousness separately as the memory of a previous passage. As you cross, you think, ' Why, I crossed this street just now : ' your nervous condition has severed two phases of a single consciousness ; the one is referred to the past ; and the other, under the regular laws of memory, arouses the feeling of familiarity. The same weakening of the associative tendencies may bring it about that a familiar, meaningful word stands out as novel and meaningless. The experience is very unpleasant ; but it loses its strangeness if we synthetise it experim,entally. Repeat a word over and over again, with sustained attention to the auditory-kin- aesthetic complex. The word soon becomes meaningless; the direction of attention has given a sort of hypnotic narrowness to consciousness, the associative context of the word is cut off, and the bare perception remains. This loss of meaning, once more, may appear on the grand scale in the state known as depersonalisation. There are moments of unusual depression or lassitude or fatigue, when the whole world about us seems new and strange, though rather negatively than 426 Memory and Imagination positively, — new and strange as a shadowy dream-world, where things are pictures, and men are pictured automata, and we hear and contemplate our own voice and action as foreign and indif- ferent spectators. Here the normal context and the normal feel- ing of familiarity are entirely lacking ; the kinaesthetic and other organic reactions have lapsed ; the cortical set that adjusts us to a world of external reality has disintegrated. We know nothing in detail of the physiological conditions of depersonalisation, but it is evidently related to the apparently opposite phenomenon of false recognition. Other illusions of memory, which follow naturally from the course of the image and the structure of the memory conscious- ness, need not here be specified. References for Further Reading §§112-120. H. Ebbinghaus, Psychologie, i., 1905, 633 fF. ; W. Wundt, Physiol. Psychol., lii., 1903, 581 ff., 628 fF. ; Die Kunst, 1908. § 112. On the course of the image, J. Philippe, Sur les transforma- tions de nos images 7nentales, in Revue philosophique, xliii., Mai 1897, 481 ff. On the memory after-image, G. T. Fechner, Elemente der Psy- chophysik, ii., 1907, ch. xliv. (J)). On perseverative tendency, G. E. MUller and A. Pilzecker, Experiinentelle Beitrdge zur Lehre voni Gedachtniss, 1900, 58 ff. § 114. F. Galton, Inquiries into Human Faculty and its Develop- ment, 1883 (reprinted as no. 263 of Everyman's Library) ; E. B. Titchener, Experimental Psychology, I., ii., 1901, 387 ff. ; A. Fraser, Visualisation as a Chief Source of the Psychology of Hobbes, Locke, Berkeley and Hume, in American Journal of Psychology, iv., 1891, 230 ff. § 115. E. A. McC. Gamble and M. W. Calkins, Die reproduzierte Vorstellung beim Wiedererkennen und beim Vergleichen, in Zeits. f. Psychol., xxxii., 1903, 177 ff. ; xxxiii., 1903, 161 ff. § 117. Cf. a series of articles by F. Kuhlmann, in American Journal of Psychology, xvi., 1905, 337 ff. ; Psychol. Rev., xiii., 1906, 3i6ff. ; Journ. Philos. Psychol. Sci. Meth., iv., 1907, 5 ff. ; American Journal of Psy- chologv, xviii., 1907, 389 ff. ; xx., 1909, 194 ff. § 118. References to current investigation, and an account of the experiments upon which this Section is chiefly based, will be found in an article by C. W. Perky, American Journal of Psychology, laa., 1910, 422 ff. On secondary sensations, see B. Sidis, Psychol. Rev., xv., 1908, References for Further Reading 427 44 ff., 106 ff. On centrifugal sensory conduction-paths, W. Wundt, Princ. of Physiol. Psychol., i.,tr. 1904, 151, 159, 182, 184, 186, 189. § 1 19. T. Ribot, Essay on the Creative Imagination, tr. igo6; E. Lucka, Die Phantasie, eine psychologische Untersuchung, 1908. § 120. G. Heymans, Eine Enqtiete iiber Depersonalisation und Fausse Reconnaissance^ in Zeits. f. Psychol., xxxvi., 1904, 321 fF. ; xliii., 1906, I S.\ J. Linwurzky, Zum Problem des falschen Wiederer- kennens {dejd vu), in Arch. f. d. ges. Psychol., xv., 1909, 256 flf. ACTION § 121. The Keaction Experiment. — In the year 1796, the astronomer in charge of the Greenwich Observatory ^ found himself obliged to dismiss an otherwise competent assistant, who, in the preceding year, had fallen into the habit of recording stellar transits some half second too late, and had now increased his error to almost a whole second. The assistant disappeared; but the error, after passing without further notice for a quarter of a century, became the topic of prolonged scientific discussion, and as the ' personal difference ' or ' personal equation ' gave rise to the psychological study of reaction times. A reaction, in the technical sense in which we are here using the term, is a movement made in response to an external stimulus. A simple reaction is a movement made in direct response to such a stimulus. In the reaction experiment, we subject the observer to some prearranged form of stimulation (say, a flash of light), to which he has to reply by some prearranged movement (say, the slipping of the forefinger from the button of a telegraph key). Instruments are employed which permit us to measure the time elapsing between the exhibition of the stimulus and the performance of the answering movement. This time is named the reaction time, and, in the case of direct response, the simple reaction time. The experiment may be made more complicated, both ^ N. Maskelyne, Astronomical Observations made at the Royal Observatory at Greenwich, 1795, pt. iii., 339. § 121. The Reaction Experiment 429 on the side of stimulus and on that of mode of reaction. We then have various forms of compound reaction, with the corresponding compound reaction times. The passage of a star across the meridian was formerly deter- mined by means of the eye and ear method. The field of the telescope is divided up, let us say, by five fine wires, set vertically and at equal distances. The middle wire corresponds to the meridian. Before putting his eye to the instrument, the observer reads off the time from a clock, and then counts the beats of the pendulum as he watches the progress of the star. He notes its position at the last beat before, and the first beat after, it crosses the middle wire, and thus estimates the time of the actual cross- ing. Thus, if the star is at a when the twelfth beat is counted, and at b when the thirteenth is counted, the time of transit, estimated in tenths of a second, will be so many hours, so many minutes, 12.7 seconds. It is in estimations of this sort that the personal difference appeared. The phrase 'personal equation * arose from the custom- ary statement of the difference in com- parative terms. Thus, A—B= 0.8 sec. means that the observer A records a transit, on the average, 0.8 sec. later than observer B. Here the one observer, probably the more skilled of the two, is made the standard of reference for the other. The equation evi- dently has only a relative value ; the magnitude of .ff's error is not dete^-mined. The discussion of the personal difference led directly to the experiments on accommodation of attention described in § 83. It also led, indirectly, to the experiments on reaction time. For these may be regarded as absolute determinations of the error of the observer : if ^ responds to the flash of light in 290 o- (i o- = Yww^ sec), and B'v\ 180 S52 ClaparMe, E., 395 Clarke, H. M.; 548 Cope, E. D., 452 Cuyer, E., 504 Darwin, C, 453, 487, 504 Descartes, R., 479 Ebbinghaus, H., 306, 333, 338 f., 346 f., 3S3 ff-, 363, 366, 373, 380 £., 395, 402, 426, 549, 552 Fechner, G. T., 399, 426, 504 Flournoy, T., 549 Fouillee, A., 504 Eraser, A., 426 Frey, M. von, 304 Galenus, C, 498 Galton, F., 404 f., 426, 548 Gamble, E. A. McC, 426 Gardiner, H. N., 503 Gebsattel, E. Freiherr von, 504 Griinbaum, A. A., 531, 548 Hammond, W. A., 374, 479 Hartley, D., 374 Helmholtz, H. L. F. von, 319, 329, 335, 338, 353. 363 Henle, F. G. J., 479 Herbart, J. F., 366 f. Hering, E., 321, 324, 325, 337 ff. Herrick, C. J., 470 HejTnans, G., 427 Hobbes, T., 374 f., 390 Holmes, O. W., 318 Hume, D., 374 f. Huxley, T. H., 527 Irons, D., 473, 479, 504 James, W., 304, 349 i-, 359. 373. 395. 404, 406, 469 f., 474, 476, 477 ff., 480 f ., 488, 494 f., 503 f., 512 f., 548 Jennings, H. S., 455 Jevons, W. S., 406 Jodl, F., 552 Judd, C. H., 339, 488 Jung, C. G., 469 Koffka, K., 348 Kuhlmann, F., 426 Kulpe, O., 395, 469 f., 504, 548, 552 Ladd, G. T., 470 Lange, C, 475 f-, 478 ff., 494 i-, 503 Langfeld, H. S., 470 Lehmann, A., 503 f. Linwurzky, J., 427 Lipps, T., 335, 339 Locke, J., 374 f. Lotze, R. H., 398, 479 Lucka, E., 427 MacDougall, R., 347 McDougall, W., 470, 480, 504 Mach, E., 334, 359, 547 Malebranche, N., 479 554 Index of Names Marbe, K., 547 Maskelyne, N., 428 Maudsley, H., 479 i Mayer, A., 547 Meinong, A., 552 Messer, A., 470, S49 MiU, J., 374 MiU, J. S., 375 Mosso, A., S45, S48 Muller, G. E., 426 Muller-Lyer, F. C, 333, 33s Miinsterberg, H., 476 Murray, E., 349 f., 490 Myers, C. S., 39s, 548, 552 Nadejde, D. C, 470 Nagel, W., 311 Okabe, T., 548 Oppel, J. J., 33S Orth, J., 547 Parry, C. H. H., 363 Paulhan, F., S04 Perky, C. W., 426 Philippe, J., 426 PiUsbuiy, W. B., 549 Pilzecker, A., 426 Poggendorff, J. C, 335 Prince, M., 549 Pyle, W. H, 548 Ranschburg, P., 381 Ribot, T., 427, 493, S03 f., 548 Rowland, E. H., 513 Sanford, E. C, 469 Schneider, G. H., 480 Scripture, E. W., 552 Sidis, B., 426 Siebeck, H., 479, 498 Spencer, H., 37s Spinoza, B. de, 479 Squire, C. S., 348 Starch, D., 339 Stern, L. W., 348, 548 Storring, G., 549 Stout, G. F., 372, 468, 473 Stratton, G. M., 320 Stumpf, C, 306, 353 ff., 360 ff., 363, 473, 503 f- Thomdike, E. L., 469 f . Truschel, L., 339 Wallin, J. E. W., 339 Ward, J., 452, S04 Washbiun, M. F., 514 Watt, H. J., 549 Weber, E. H., 323, 327, 342 Wheatstone, C, 316 flE., 319 Whipple, G. M., 548 Woodworth, R. S., 512 Wundt, W., 304, ii%, 338 f., 346 f., 3S5. 360 ff., 363, 366 f., 392 ff., 395, 426, 427, 441 f-, 452, 467, 469, 491 f., 503 f., 524, 540 ff., 548, 552 Voakum, C. S., 548 Ziehen, T., 398 ZoUner, F., 335 Zoth, O., 338 INDEX OF SUBJECTS Abstraction, sag f. Accent, subjective, 345 Accommodation, visual, sensations from, 314 f. Action, definition of, 448; genesis of, 450 S.; nature of earliest, 452 fi. ; classification of, 458 ff. ; impulsive, 458 f. ; ideomotor and sensorimotor, 458 f . ; voluntary, 459, 542 ; selective, 459 ; volitional, 460 £. ; instinctive, 462 flf. ; as motived by affection, 468 f. Acuity, visual, 324 f. iEsthesiometry, 322 f. Esthetics, experimental, 500 ff. Affection, as motive to action, 468 f . Affection, as reflexly excited sensation, 476, 482, 494; in James' theory of emotion, 477 f. After-image, of movement, 360; mem- ory, 399 f . Analysis of perception, 350 f., 369, 372 f. Apperce[5tion, doctrine of, 366 f. Apprehension, direct, 410 ff. ; disturb- ance of, 412 f. Association, Aristotle's rules of, 374; traditional laws of, 374 ff., 379 f. ; two meanings of term, 377 ; law of, 378 ff. ; not an affective phenomenon, 378 f. ; implies attention, 370, 383, 386; initiated by similars, 379; ex- perimental study of, 380 ff., 443 ff. ; remote, 385, 388, 402 ; direct, 385, 388, 402 ; retroactive, 385, 402 ; incidental, 38s f . ; mediate, 386 ; modes of, 389 ; and perception and idea, 389 f . ; suc- ces'sive and simultaneous, 390; classi- fication of, 390 f. ; introspection of, 391 f . ; conscious mechanism of, 394 ; physiological mechanism of, 394 ; ver- bal, 3Q7 f. ; breaking up of, 401 f. ; individual differences in, 405 Attention, in retinal rivalry, 320; and qualitative perception, 349 f.; and association, 379, 383, 386; in recita- tion of learned series, 384 ; and imagi- nal type, 405 ; and memory, 413 f. ; and imagination, 422; in simple re- action, 432 ff. ; in emotion and sen- timent, 499; implies dual division, S40 f., 543, 544 Attitude, conscious, 330, 333 f., 398, 423, 433 ff., 443, 445 f . ; nature of, 505 ff. ; intellectual and emotive, 505 f . ; anal- ysis of, 515 ff. ; theory of, 520 f. Blind, spatial perception of, 308, 331, 338; warning sense of, 331 £. Blind spot, 328 f. Change, index of, 343 £. Colour mixture, binocular, 321 Combination, form of, 371 ff., 409, 518 Comparison, 532 ff. Complex, associative, 446 Conation, 467 f. Concept, 527 ff., 536 Cones, retinal, 324; perception of ex- tents by single, 327 Consciousness, associative, 389 S., 444 f . ; recognitive, 407 ff. ; memory, 413 ff . ; imaginative, 421 ff. ; action, 448 f. ; appearance of, 451 ff., 457 ; instinctive, 463 f . ; will, 466 f . Consonance, theories of, 361 f. Contiguity, association by, 375 f., 379 f., 394 f- Contrast, association by, 375 f. Convergence, sensations from, 314 f. Correspondence, retinal, 309 f . Cramming, 406 Depersonalisation, 425 f. Depth, perception of, 306 ff. ; tactual, 306 ff. ; visual, 308 ff. ; monocular, 31s; indirect criteria of, 313, 316; direct criteria of, 315 f. ; limen of visual, 324 f. Description, 510 f. 556 Index of Subjects Difference, experience of, S3S f- Differential psychology, 403 ff., S44 f- Dimensions, spatial, 307 f. Direction, law of identical visual, 325 Discrimination, 532 ff. ; temporal, 342 Dissociation, 401 f . Distance, interocular, 311, 324 £• Duration, as attribute of sensation, 340 ff . Dynamogenesis, 488 f . Elements, mental, 372 f. Emotion, nature of, 471 ff., 4gi ; ex- perimental study of, 472 f . ; and feel- ing, 473 ; James-Lange theory of, 474 ff., 476 ff., 481 ff. ; anticipations of, 479 f . ; and instinct, 480 ; and organic sensations, 481 ff. ; unmo- tived, 481 f. ; trimcated forms of, 483 ; expression of, 484 ff . ; forms of, 489 ff. ; composite, 492 f . ; and sen- timent, 499 Empathy, in optical illusions, 333; in imagination, 417, 423 ; in experience of relation, 514 Equation, personal, 429 Expansion, affective, 495 Expectation, 537 f. Expression, method of, 484 f ., 503 Extent, as attribute of sensation, 303 ff., 327 Eye, spatial field of, 30s f. Eye and ear method, 429 f. Eye-movement, importance of, for per- ception of depth, 313 ff. ; in optical illusions, 333 ff. ; in perception of movement, 358 Facilitation, nervous, 461, 530 Familiarity, feeling of, 407 ff., 411, 413, 419 Fatigue, 537 f., S39 f- Feeling, and emotion, 473 Fixity, neural, 456 ff., 463 Form, perception of, 327 f. Fovea, structure of, 324 Fusion, in qualitative perception, 349; tonal, 351 f. ; theory of, 352 ff. ; and consonance, 361 f, ; in Wundt's doctrine of association, 393 ff. ; of emotions, 492 f. Genetic psychology, 408, 410, 452 ff., 48s f. ; false, 350 f., 369, 372 £. Generalisation, 529 f., 531 f. Gesture, 461 f., 524 f. Grey, seen at blind spot, 328 f. Habituation, 537 f., 539 Hallucination, 420, 515 Horopter, 309 £. Idea, and perception, 376; of associa- tionism, 376 f., 528 f. ; and association of ideas, 389 f. ; nature of, 393 ; ab- stract or general, 525 ff. ; aggregate, 540 f. Illusions, geometrical, of sight, 332 ff. ; of reversible perspective, 334 f. ; tem- poral, 342 f . ; of movement, 358 ; of memory, 424 ff. ; affective, 496 f. Image, part of, in perception, 364 ff., 371 ; course of, in consciousness, 396 ff. ; has attribute of intensity, 398;. experimental study of, 397 f., 399; in memory, 414 ff . ; in imagination, 424; organic, 494; composite, 526 f. Imagery, types of, 366, 368, 403 ff . ; in attitude, s'? f-> S19. S28; in com- parison, S33 f. Images, double, 309; disparity of, and tridimensional vision, 310 ff. Imagination, and perception, 365 ; and memory, 416 ff. ; psychology of, 422 ff. Imagination, image of, 416 ff.,. 418 ff. ; theory of, 420 f. Impression, absolute, 312 f., 398, 533, 536 Impression, nervous, conditions of, 382 ff. ; and length of series, 383 f. ; and repetition, 383 ; and distribution in time, 383 f., 402; and reading by whole or part, 384; relation of, to learning, 384; in childhood, 402 Impulse, 458 f . Incorporation of meaning, 467, S19 f ■■ S42 Indirect vision, parallax of, 313 ; acuity of, 324 Infant, movements of, 4S4 Inhibition, nervous, 461, S3o Inhibition, retroactive, 387; terminal, 387 f . ; initial, 388 Innervation, sensation of, 441 Instinct, 462 ff. ; classification of, 463 f . ; and emotion, 480 Intensity, as attribute of image, 398 Introspection, favoured by instruction to introspect, 446; affective, 472 f. Index of Subjects 557 Judgment, psychology of, 540 ft.; im- plies secondary attention, 542 f . ; and voluntary action, 542; experience of, 544. S46 f- Kinaesthesis, importance of, for mean- ing, 368, 371 ; for direct apprehen- sion, 411 f. ; in experience of relation, S13 f- ; in experience of reality, 514 f. Kinematograph, 359 Language, as witness to organic factors in emotion, 483 f . ; primitive, 486 ; and thought, 521 S. ; psychological ad- vantages and disadvantages of, 522 ff. ; origin of, 523 fi- ; development of, 523 f-, 52s Law, Weber's, 327, 342, 357 f. ; of asso- ciation, 378 ff., 395 ; of dynamogenesis, 488 f. ; of mental growth and decay, 370, 376, 411, 483 Learning, 384, 405 f. Life, genesis of, 455 f. Limen, stimulus, 474 f. Local sign, 304, 335, 337 Localisation, visual, 304 ff., 321 f., 324 f. ; cutaneous, 305 f., 322 ff. ; of fixation- point, 312 f. ; secondary criteria of, in perception of depth, 313, 315; monocular, in perception of depth, 315; of organic sensations, 325 f. ; of odours, 330 ; of sounds, 330 f . ; tem- poral, 340 ff. Locality, perception of, 321 ff. ; cuta- neous, 322 ff. Lustre, binocular, 320 f. Magnitude, perception of, 326 ff. Meaning, psychology of,, 367 ff., 376, 3?8 f., 51.7 f. ; carried physiologi- cally, 3§9.f.," 37$; in associationism, 376 f. ; loss of, 425 Mefody, perception 'of, 360 ff . ; and form of combination, 372 ^ Memory, 396 ff., 413 ff. ; and kinaes- thesis, 417 ; illusions of, 424 ff. ; emo- tive, 493 ff . ; failure of, with age, 536 Memory-image, 416 f., 418 f.; theory of, 420 f. Method, of trial and error, 487 Mood, 497 Movement, alleged sensation of, 356 f. ; function of, in perception of space. 306 ff . ; perception of, 356 ff. ; exten- sive limen of, 357; illusions of, 358; synthesis of, 358 f. ; after-images of, 360; sensations of intended, 434, 441 f. ; theory of, 442 ; 'see Eye-move- ment, Kinaesthesis Music, development of, 361 ff. Nonsense syllables, in work on associa- tion, 380 ff ., 414 ; in work on abstrac- tion, 530 ; forms, in work on general- isation, 531 f. Odours, localisation of, 330 Organic sensations, locaHsation of, 325 f. ; in instinct, 464; in emotion, 472, 474 ff., 481 ff. ; and self-experience, 544, 546 f- Parallax, binocular, 311 f.; of indirect vision, 315 Paramnesia, 425 Passion, 497, 500 Perception, spatial, 303 ff. ; of depth, 306 ff. ; of locality, 321 ff., 330 ff. of magnitude, 326 S. ; illusory, 332 ff. theories of, 335 ff. ; temporal, 340 ff. two groups of, 343 ; of rhythm, 344 f . theories of, 346 f . ; qualitative, 349 ff. tonal fusion, 351 f. ; theories of, 352 ff. simple and composite, 356; of move- ment, 356 ff. ; of melody, 360 ff. ; pure and mixed, 364 ff. ; and form of com- bination, 371 ff. ; and association of ideas, 389 f. Personahty, multiple, 547 Plane, nuclear, 338 Plasticity, neural, 456 ff., 463 Practice, 537 ff. Predisposition, 309, 320, 323, 330, 334, 359 f., 369 ff., 386, 389, 473, 483, 492 Present, conscious, 340 ff., 369 Pressure spots, spatial distinction of, 323 f. ; perception of extent by, 327 Pseudoscope, 319 f. Psychology, status of, 549 ff. Qualitative perceptions, 349 ff. Reaction, definition of, 428 f., 447 f. ; history of, 430 f. ; technique of, 431 f. ; simple, analysis of, 432 ff. ; sensory, 432, 435 ; muscular, 432, 434 ff.; 558 Index of Subjects Reaction — Continued mixed, 432 ; norms of, 432 ; instruc- tions for, 433 f. ; periods of, 434 ff. ; variations of, 437 ; compound, 437 ff- ; discriminative, 438, 442; cognitive, 438 I., 442 ; choice, 439 ff., 442 ; sub- tractive procedure in, 443 f. ; asso- ciative, 443 fi. ; with negative in- struction, 460 f . Reality, feeling of, 514 f. Reasoning, 543 f . Recognition, analysis of, 407 ff . ; defi- nite and indefinite, 409; direct and indirect, 409 f. ; lack of, 410; and direct apprehension, 410 ff. ; and meaning, 411 f. ; and memory, 413; illusions of, 424 ff. Recollection, 414 ff. Reflex action, 451, 458 f., 462; genesis of, 452 f., 462 Relation, alleged elements of, 511 ff. Relationship, tonal, 362 Remembrance, 414, 416 Retention, 396 ff., 401 f., 403 ff. Rhythm, perception of, 344 f. ; visual, 345; subjective, 345 Rivalry, retinal, 309, 320 f. Scale, musical, 361 ff. Self, psychological, 544 ff. ; genesis of, 546 Self-consciousness, 544 f . Selves, science of, 551 f. Sensation, single, has no meaning, 367 Sensations, cutaneous, 305 Sense-distance, 361 f. Sentiment, nature of, 498 f. ; definition of, 500; forms of, 500 ff. ; aesthetic, 500 ff . ; intellectual, 502 ; social and religious, 502 f . ; expression of, 503 Set, nervous, 309, 320, 323, 330, 334, 369 ff., 376, 386, 398, 422 f., 445, 461, S36 Similarity, association by, 37s f., 379 f., 394 Situation, psychological, 367, 369, 478, 490 Skimming, 406 Skin, spatial field of, 305 f . Sound, localisation of, 330 f. Space, perceptions of, 303 ff . ; variety of psychological, 329 f. ; secondary. 330 ff. ; illusory, 332 ff. ; theories of, 335 ff- SpeciaUsation, associative, 445 f., 461 ; of instinct, 465 Stereoscope, reflecting, 316 f. ; refracting, 316 ff. Stimulus-error, 350, 398, 322 Strangenessr feeing of, 417 f., 419, 423 Stroboscope, 3s8 f. Suggestion, 449 f. Syngesthesia, theory of, 420 f. Synthesis, of tridimensional space, 316 ff. ; of visual movement, 358 f. Taste, spatial value of, 305 Telestereoscope, 319 Temperament, 498 Temporal sign, 346 Tendency, associative, 384 ff ., 395, 400 f ., 401 f., 521 ; effect of age upon repe- tition, 402 ; and reaction time, 446 Tendency, determining, 449, 461, 521, S30 Tendency, impressional, 384, 39s, 400 f. Tendency, instinctive, 464 f., S4S Tendency, perseverative, 400 f., 437 Theory, genetic and nativistic, of space perception, 335 ff . ; of time percep- tion, 346 f. ; of tonal fusion, 3S3 f. ; of qualitative perception, 355; of movement, 356 f., 360; of image of imagination, 420 f. ; of sensations of intended movement, 442; general, of mental phenomena, 489 Things, science of, 351 f- Third dimension, see Depth Thought, alleged element of, so8 ff. ; imageless, 512 f., 514, 518, 521; and language, 521 ff. Time, perceptions of, 340 ff. ; bidimen- sional, 340 f . ; and space, 341 ; per- ception of rhythm, 344 f . ; theories of, 346 f- Transfer, affective, 495 f . Tropism, 454 f. 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