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or the sound of a melody or of a pattering of rain are examples of the latter.

The Constitution of Percepts.-Elementary sensations are said to combine to form percepts. When the combination is by the juxtaposition in space of the elements, as when different bits of blue make a blue surface or different bits of pressure give the feeling of a hand pressed against the brow, the combination is called colligation. When the elements do not each exclude the other from occupying the same space, as when different tones combine to form a chord, or when tastes and smells and touch combine to form the total 'taste' of celery, the combination is called fusion. Since this combination is really a combination, not of feelings, but of the processes in the brain upon which they depend, the account of the way in which percepts are built up will be given in Part III.

Exercises

I. Give illustrations of illusions and of hallucinations from your own and from your friends' experiences.

2. a. Which senses provide percepts of the form of objects? b. Which senses provide percepts of the texture of

objects?

C. Which senses provide percepts of the weight of ob

jects?

3. What terms in grammar refer respectively to single and collective percepts?

4. Give three illustrations of the influence of training in replacing vague and coarse percepts by definite and detailed percepts.

5. What paragraphs in the text bring out the facts stated in these quotations?

a.

"Consciousness is never composed of a single sensation." (Titchener).

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b. "The consciousness of particular material things present to sense is nowadays called perception." (James).

c. "Every perception is an acquired perception." (James).

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Experiment 5. Sensations and Percepts.-a. Look at Fig. I A. Find the two frogs. Notice the change from a vague blur of lines to a definite picture as the frogs spring into view.

b. Look at a landscape with the head turned upside down; then with the head in its usual position.

c. Look through the pages of an illustrated magazine, held upside down or turned through an angle of 135 degrees from its usual position. When a picture appears as a mere chaos of sensations, turn the magazine to its usual position and note the difference in the picture's definiteness and 'thingness.'

Experiment 6. Percept and Stimulus.-Look at Fig. 1 B. What is it? Continue looking until you find another animal shown. Show the figure to six or eight people, letting each one tell at once what it is. What sentence in the text do the results illustrate?

References

A. James, Briefer Course, XX. (312-315).
Stout, Manual, 312-391.

Titchener, Outline, §§ 43-51.

B. Ebbinghaus, Grundzüge, §§ 37-41.

James, Principles, XIX. (76-82).

Wundt, Physiologische Psychologie, XI.-XIII.

1 I am indebted to the publishers of St. Nicholas for permission

to use FIG. I A.

CHAPTER III

FEELINGS OF THINGS AS ABSENT: IMAGES AND MEMORIES

§ 9. Mental Images

Definition and Classification.-The term Imagery or Images is often restricted to feelings of things as not present. A more useful meaning, and one that prevails in recent books on psychology, is feelings of things, qualities and conditions of all sorts as not present. In this sense of the word there may be an image to correspond to every sensation, percept, impulse or emotion. There may be images of fatigue, fear, lonesomeness and tickling, as well as of faces or tunes. The most frequent images are however of sights, sounds and movements.

Images are naturally classified according to the kind of sensation or percept or impulse or emotion to which they correspond. The most important groups are:

Images of sights:-Visual Images.

Images of sounds:-Auditory or Audile Images.
Images of feelings of movement:-Motor or Mo-
tile Images.

Images of touches:-Tactile Images.
Images of tastes:-Gustatory Images.

Images of smells:-Olfactory Images.

The reader may be unable to get images of all these different kinds. Images of tastes and of smells are comparatively rare and some individuals can be found who apparently lack visual and auditory images.

A group of images which is of much practical importance is formed by images of words. More of human thinking, especially of that of educated men and women, is done by imaged words than by imaged objects. It should be noted that whereas for images of objects the order of frequency is visual, auditory, motor, the order of frequency for images of words is probably motor, auditory, visual. Possibly auditory, motor, visual is the order, but common opinion often mistakes a motor for an auditory image. The more one observes his images of words, the more he will find motor factors and approach agreement with the following statement by Bain:

'When we recall the impression of a word or sentence, if we do not speak it out, we feel the twitter of the organs just about to come to that point. The articulating parts -the larynx, the tongue, the lips are all sensibly excited; a suppressed articulation is in fact the material of our recollection, the intellectual manifestation, the idea of speech."1

Generic Images. In certain cases the conditions are especially favorable for the production of vague, hazy, incomplete images; namely, when many things alike in certain features and unlike in others have been experienced. For instance, the many different percepts that have been associated with the word dog result in a tendency of the process of reproduction toward an image of a dog of indefinite and fleeting size, color and shape. In such cases the different percepts contribute elements which in some cases agree enough to reinforce each other, in others are so contradictory as to annihilate each other, and in all cases tend somewhat to give way in succession to each other. We may compare the process to that of

'Quoted by James, Principles of Psychology, vol. II., p. 64.

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making composite photographs in which each of a hundred or so faces has its share. Or the process may be likened to the clamor of a thousand men saying something alike in part and different in other parts. Out of it all comes to the listener a vague feeling of the general thought of the assembly. A mental image which possesses clearly only the commonest features of a class of objects, being incomplete and hazy and changing in all minor details, is called a Generic Image.

"In dreams, one sees houses, trees and other objects, which are perfectly recognisable as such, but which remind one of the actual objects as seen ‘out of the corner of the eye,' or of the pictures thrown by a badly-focused magic lantern. A man addresses us who is like a figure seen by twilight; or we travel through countries where every feature of the scenery is vague; the outlines of the hills are ill-marked, and the rivers have no defined banks. They are, in short, generic ideas of many past impressions of men, hills, and rivers. An anatomist who occupies himself intently with the examination of several specimens of some new kind of animal, in course of time acquires so vivid a conception of its form and structure, that the idea may take visible shape and become a sort of waking dream. But the figure which thus presents itself is generic, not specific. It is no copy of any one specimen, but, more or less, a mean of the series.'

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Variation in Images. Images differ greatly in clearness, in fidelity and in susceptibility to control. One may have a perfectly distinct image of his father's face, one which accurately corresponds detail for detail with the real percept and which can be gotten at any time and retained before the mind's eye at will; but his image of a certain house or of a regular polygon of twenty sides may be vague, rough and fleeting. Between individuals the difference is even more marked.

One may be able at

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