A Beginner's Psychology

by Edward Bradford Titchener

[§ 29]. The Problem in Detail.—Every one of our familiar perceptions might, now, be treated in this same fashion, and in indefinitely greater detail. We should start out with our pattern of sensory nucleus, imaginal context, and brain-habit; and we should push our analysis back and back, in the effort to reach the primary and ultimate form of the perception we were discussing. The quest is fascinating; for these are old, old bits of the mental life; to trace them home would be to go back to the Stone Age—or further; the earliest men we know of perceived the things that we perceive. Whether psychology will ever reach the final goal cannot be said; but at any rate the problems are genuine problems; they can be resolved only by intensive and long-continued work; and they demand an extraordinary ingenuity in the devising of experimental controls and an unusual degree of patience in experimenting. Men spend their lives among dead languages and buried cities; why not excavate and explore the inner world of perception?

Let us take an instance or two. Consider, first, the perception of movement by the eye. Many psychologists assume outright a special sensation of movement, something that we might call a travel-sensation. That hypothesis cuts the difficulty; but the sensation is no more admissible than the depth-sensation, and for like reasons. Other psychologists call attention, in a more scientific spirit, to the fact that in all cases of sudden change there is a sensory index of that change. If, for instance, a tone is quickly changed to a higher tone, or a light suddenly reduced to a duller light, there is a moment of sensory blur or confusion, a moment in which the quality or intensity ceases to be clear and distinct; so that, if you were called upon to identify it, you could say only ‘It lies somewhere about such-and-such a part of the scale.’ This blur is the sensory index of change; not a new sensation, but a modification of existing sensation. We have it in the perception of visual movement; there is a blur of positions; and it may reasonably be referred to the positive after-image. A shooting-star flashes across the sky; it leaves a trail of after-image as it moves; you see it both at the place it started from, and at the place where it disappears, all in the same present time; thinking of it, nevertheless, as a star, a point of light like other stars, you perceive movement. The same thing holds for the perception of rapid movement on the skin.

So far everything is in order. Now, however, let us make a simple experiment. You know the stroboscope or zoetrope that is sold in the toy-shops: a cardboard drum, open at the top, that twirls on a handle; a strip of paper, on which are printed phases of some movement (the flight of a bird, the gallop of a horse), is placed inside, round the bottom of the drum; and you look down at the strip, while the instrument revolves, through vertical slits cut at regular intervals in the upper half of the drum-wall; you then see a continuous movement. Suppose that you make a new strip, on which you draw simply two lines, a vertical and a horizontal; you draw them some distance apart, but in such wise that, if they came together, they would form a right-angle. Turn the drum slowly, and you see the two lines; turn it swiftly, and you see the right-angle, like a letter L; turn it at a middle rate, and you see—according to the direction of turn—the vertical fall over into the horizontal, or the horizontal rise up into the vertical. You see movement, where there is no movement to see! Here, then, is a case of perception of movement in terms of sheer brain-habit, of a settled nervous disposition that now has no mental correlate, but whose establishment has depended on the past history of the individual, possibly of the race.

Take, as a second instance, the perception of melody. Primitive melodies seem to be of two types. In the one, the scale arises by synthesis of small tone-steps or tone-distances, which are approximately ‘whole tones’; the melody consists only of two or three of these steps, and the last and lowest tone is the principal note of the tune. In the other, the scale arises by analysis of the larger consonant intervals, fourth and fifth; these intervals are broken up into smaller steps; the octave appears as a drone-bass; the first and highest tone is the principal note. An intermediate type keeps for the most part to small steps, but shows ascents and descents portamento through octave, fifth and fourth; it, too, makes the first and highest tone the principal note. We can account for a good deal of this development: we know that the voice cannot be evenly sustained in recitative, but naturally drops; we have reason to believe that the memory of absolute pitch is strongly developed in primitive peoples (parrots repeat their tunes at the same pitch, and the same thing is largely true of young children); we know the recurrent tonality of the octave (p. 52); we know that the fourth is the natural drop of the voice at the end of a sentence, and the fifth its natural rise in asking a question; we know that men, women and boys, singing in ‘unison,’ will really sing in octaves, and often in fifths and fourths; we know that the semitone, the final unit of our own scales, is the smallest tone-step that can be accurately sung; we know that musical instruments were invented very early, and that they must have helped to give stability to the vocal scale. These things, however, are not enough. For behind all music lies what we must call an intent to express, as behind all speech lies an intent to communicate; and this intent baffles us; we can only say, once again, that it is carried by some native and ingrained disposition of the nervous system. The possibility of music is further bound up with the possibility of transposition; the melody must be reproducible and recognisable, whatever note it start from; and primitive melodies do in fact begin on different notes, and yet keep the same form. It may be that the primitive singer felt his tones, felt the adjustment of his larynx, more keenly than we do. Movements of the larynx are muscular contractions, and their sensations are subject to Weber’s law (p. 68); so that, whether the vocal cords are slack or tense, their tension must be increased in the same proportion to get equal differences in muscular sensation. Here is a possible organic basis for the relative constancy of the tones within a melody; the difficulty is that even primitive melodies seem to be shaped, not by feel, but by ear.

We may take, as a third instance, a group of perceptions that have been named optical illusions. In a certain sense, most of our space-perceptions are illusory. Distance, for example, soon closes up on itself; if we try to stop, halfway, a friend who is walking down a long corridor, we shall be likely to call out before he has gone more than a third of its length. Size is illusory; the size of the moon in the sky is that of a pea held at arm’s length before the eyes. Form is illusory: how often do we see a table square? Only direction is adequately perceived. Yet we do not, somehow, think of all these things as illusions; we are used to them, and can make allowance for them.

There are, on the other hand, certain simple arrangements of dots and lines that yield, in perception, a result markedly different from that which measurement would lead us to expect. These figures have, in recent years, been made the subject of detailed study; that which is here shown has, in particular, been repeatedly discussed and variously explained. The simplicity of the forms is, indeed, treacherous and misleading; analysis is very difficult; and there is no present prospect that investigators will agree.

The two horizontal lines are equal in measurement; they are unequal to the eye. Why? One suggestion is that the eye moves freely along the one, and hesitatingly and obstructedly along the other; the obliques tempt out, in the one case, and hem in, in the other. The suggestion can be tested; for movements of the eyes can be recorded; and it turns out to be correct. The eyes, in passing over a line, like the lines of the figure or of a printed page, move by sweeps or jerks; they go so far, halt, and start again. Experiment shows that movements along the lower horizontal take a longer sweep, and oftentimes come to a halt only when they have shot beyond the end-points of the line; whereas movements along the upper horizontal are themselves shorter, and frequently come to a halt before the extremities of the line have been reached. Here, then, is a kinæsthetic context to carry the meanings ‘longer’ and ‘shorter.’ Is the analysis adequate? Not for every case; the illusion is found to vary with our general attitude toward the figures. If we take them as wholes, the large open area below and the closed diamond-shaped area above strike the attention; we say, from total impression, that the lower horizontal is the longer. If, however, we take the figures critically, part by part, limiting our attention to the horizontals and disregarding the obliques, then the illusion is greatly reduced and may, with practice, disappear. Here, then, is a second context, which involves a brain-habit. Another suggestion is that linear perspective may be at work; the larger figure is a book opening toward you, the smaller is a book opened away from you; the lower horizontal is therefore further off, and should (if the two books were of the same size) be smaller than the upper; since it is not, the lower book is seen as the larger. There are, without doubt, many figures in which perspective influences the perception; but there seems to be no reason to invoke it here. A fourth suggestion is that we read into the figures ideas of our own muscular state; the lower figure has room to expand, it is stretching and yawning; the upper is cramped and huddled; and so the illusion of length is produced. There is no doubt, again, that this putting of oneself in place of the lines plays a part in certain perceptions; but its influence here is negatived by the swallow figure; the birds flying toward each other are further apart than those flying from each other. On the whole, we may be satisfied with the two contexts first mentioned; the discussion shows, however, how many and how various motives may enter in to determine an illusory perception.

[§ 30]. The Types of Idea.—Idea takes its plan from perception; and ideas may therefore be classified, like perceptions, as qualitative, temporal and spatial. When, however, we speak of types of idea, we usually have a different classification in view. Our ideas differ as our equipment of imagery differs; some minds are rich in visual or auditory images, others are poor or deficient. When first these differences were brought to light, they seemed to be permanent and clearly marked; children, especially, were classed as eye-minded, ear-minded, and touch-minded or motor-minded, according as their ideas consisted predominantly of visual, auditory, or kinæsthetic images; and it was thought no less necessary to discover a child’s type, and to instruct him in accordance with it, than it is to test the colour-vision of pilots and engineers. Moreover, since all ideas may be translated into words, and since verbal ideas may also be visual, auditory or motor,—ideas of the word seen, heard, or spoken,—three sub-types were added to the main types of idea; the verbal-visual, the verbal-auditory, and the verbal-motor. The doctrine of types found support in pathology; thus, the famous French physician J. M. Charcot reports a case of eye-mindedness in which visual ideas were suddenly lost. The patient writes: “I possessed at one time a great faculty of picturing to myself persons who interested me, colours and objects of every kind; I made use of this faculty extensively in my studies. I read anything I wanted to learn, and then shutting my eyes I saw again quite clearly the letters with their every detail. All of a sudden this internal vision absolutely disappeared. Now I cannot picture to myself the features of my children or my wife, or any other object of my daily surroundings. I dream simply of speech. I am obliged to say things which I wish to retain in my memory, whereas formerly it was sufficient for me to photograph them in my eye.”