19 November 2012

The Invariant Cat

Filed under: Movies, Psychology — ktismatics @ 3:32 pm

[From The Ecological Approach to Visual Perception by James J. Gibson, 1979 — Chapter 15, “Pictures and Visual Awareness”]

To see the environment is to extract information from the ambient array of light. What is it, then, to see a picture of something? The information in ambient light consists not of forms and colors but of invariants. Is it implied that the information in a picture does not consist of forms and colors but of invariants likewise? That sounds very odd, for we suppose that a picture is entirely composed of forms and colors. The kind of vision we get from pictures is harder to understand than the kind we get from ambient light, not easier…

*  *  *

When the young child sees the family cat at play the front view , side view, rear view, top view, and so on are not seen, and what gets perceived is the invariant cat. The child does not notice the aspects of perspectives of the cat until he is much older; he just sees the cat rolling over. Hence, when the child first sees a picture of a cat he is prepared to pick up the invariants, and he pays no attention to the frozen perspective of the picture, drawing, photograph, or cartoon. It is not that he sees an abstract cat, or a conceptual cat, or the common features of the class of cats, as some philosophers would have us believe; what he gets is the information for the persistence of that peculiar, furry, mobile layout of surfaces.

When the young child sees the cat run away, he does not notice the small image but the far-off cat. Thus, when he sees two adjacent pictures of Felix in the comic book, a large Felix at the bottom of its picture and another small Felix higher up in its picture, he is prepared to perceive the latter as farther off. When he sees the cat half-hidden by the chair, he perceives a partly hidden cat, not a half-cat, and therefore he is prepared to see the same thing in a drawing.

The child never sees a man as a silhouette, or as a cutout like a paper doll, but probably sees a sort of head-body-arms-legs invariant. Consequently, any outline drawing of this invariant is recognized as a man, and the outlines tend to be seen as the occluding edges of a man with interchangeable near and far sides. Even when the outlines give way to line segments, as in so-called stick figures, the invariant may still be displayed and the man perceived…

To summarize, a picture is a surface so treated that it makes available an optic array of arrested structures with underlying invariants of structure. The cross-sections of the visual angles of the array are forms, but the invariants are formless. The array is delimited, not ambient. The array is arrested in time, except for the case of the motion picture… A picture is a surface that always displays something other than what it is…

*  *  *

By gradual stages human children begin to draw in the full meaning of the term — to draw a man or a woman, a house, a flower, or the sun in the sky. The child is still making lines on a surface that record the movements of the tool in his hand, but he is now also recording an awareness in terms of the invariants he has picked up. He delineates for himself and others something he has apprehended or experienced. The traces he leaves on the paper are not just lines, or the outlines of forms, but the distinguishing features of the environment. While drawing, he may be looking at something real, or thinking about something real, or thinking about something wholly imaginary; in any case, the invariants of his visual system are resonating. The same is true of the artist as of the child. The invariants are not abstractions or concepts. They are not knowledge; they are simply invariants…

Drawing is never copying. It is impossible to copy a piece of the environment. Only another drawing can be copied. We have been misled for too long by the fallacy that a picture is similar to what it depicts, a likeness, or an imitation of it. A picture supplies some of the information for what it depicts, but that does not imply that it is in projective correspondence with what it depicts.

*  *  *

If this new theory is correct, the term representation is misleading. There is no such thing as a literal re-presentation of an earlier optic array. The scene cannot be reestablished; the array cannot be reconstituted. Some of its invariants can be preserved, but that is all…

The efforts made by philosophers and psychologists to clarify what is meant by a representation have failed, it seems to me, because the concept is wrong. A picture is not an imitation of past seeing. It is not a substitute for going back and looking again. What it records, registers, or consolidates is information, not sense data.

*  *  *

A picture is not like perceiving. Nevertheless, a picture is somehow more like perceiving an object, place, or person than is a verbal description… The picture is both a scene and a surface, and the scene is paradoxically behind the surface. This duality of the information is the reason the observer is never quite sure how to answer the question, “What do you see?” For he can perfectly well answer that he sees a wall or a piece of paper. It is this duality in the optic array from a picture that makes the drawing a bad way to begin the study of perception…

A picture is both a surface in its own right and a display of information about something else. The viewer cannot help but see both, yet this is a paradox, for the two kinds of awareness are discrepant. We distinguish between the surface of the picture and the surfaces in the picture. In such paintings as those of the impressionists, we can see the difference between the illumination of the picture and the illumination in the picture. The two sets of surfaces are not comparable, and the two kinds of illumination are not commensurable…

*  *  *

Psychologists have long been showing inkblots to their subjects and asking what they saw. A set of such random blobs on cards devised by Hermann Rorschach has now been standardized and is in use by clinical psychologists. Faced with a card, a sensible patient might very well say simply that she saw a blot, but she seldom does. She attends to the nameless squiggles, contours, textures, and colors and says, “A bleeding heart” or “A pair of dancing bears,” allowing the psychologist to diagnose her fantasy life. I have argued that a Rorschach blot is a picture of sorts containing information not only for bleeding hearts and dancing bears but for dozens of other events. It is different from a regular picture in that the invariants are all mixed up together and are mutually discrepant instead of being mutually consistent or redundant. It is rather like a mass of scribbles for a child in this respect.

The old mentalistic explanation of perceiving objects in clouds and inkblots, incidentally, is projection, the projecting outward of fantasy images from the unconscious mind as if by a mental magic lantern. Hence, the Rorschach is called a “projective” test. This is mischievous nonsense. But the dogma of two different contributions to perception, one objective and one subjective, one coming from the world and the other coming from the mind, is so strong that the notion of a picture being thrown outward to mix with a picture being thrown inward is widely believed.

What are we to call the tree in the photograph, or the bleeding heart in the inkblot? Neither is an object in my terminology. I am tempted to call them virtual objects. They are not perceived, and yet they are perceived. The duality of the information in the array is what causes the dual experience… I conclude that a picture always requires two kinds of apprehension that go on at the same time, one direct and the other indirect. There is a direct perceiving of the picture surface, along with an indirect awareness of virtual surface — a perceiving, knowing, or imagining, as the case may be.

*  *  *

The invariants display a world with nobody in it, and the perspective displays where the observer is in that world… What is induced in these pictures is not an illusion of reality but an awareness of being in the world. This is no illusion. It is a legitimate goal of depiction, if not the only one…

Visual scientists with all their theorizing know little about the actual art of painting. A fine art should not be subject to rules and regulations. This is the attitude of many modern painters and most schools of art. The theory that artificial perspective is no more than a convention of Western art is a way of justifying this attitude. E. Panovsky (1924-1925) asserted that perspective is “symbolic.” G. Kepes (1944) has written about the “language” of vision. R. Arnheim (1954) believes that we will learn to see what is represented by abstract painters even if we now cannot. And N. Goodman (1968) in Languages of Art assumes that depiction is fundamentally description, that we learn to read a picture as we learn a language, and that linear perspective could just as well be reversed from the way we have become accustomed to interpret it.

Now it is one thing to argue that the use of perspective is not necessary for a painting, but it is quite another to say that perspective is a language. That says that both the perspective and the invariants of a picture must be analogous to words and that, just as we can learn a new vocabulary, so we can learn a new mode of perception. If a language of words can be invented such as Esperanto, why not a language of art? But the essence of a picture is just that its information is not explicit. The invariants cannot be put into words and symbols. The depiction captures an awareness without describing it. The record has not been forced into predications and propositions. There is no way of describing the awareness of being  in the environment at a certain place. Novelists attempt it, of course, but they cannot put you in the picture in anything like the way the painter can.

*  *  *

It has been generally believed that even adults can become conscious of their visual sensations if they try. You have to take an introspective attitude, or analyze your experience into its elements, or pay attention to the data of your perception, or stare at something persistently until the meaning fades away. I once believed it myself. I suggested that the “visual field” could be attended to, as distinguished from the “visual world,” and that it was almost a flat patchwork of colors, like a painting on a plane surface facing the eye. The awareness of depth in the scene could not be wholly eliminated, I thought, but it could be reduced. The similarity to a painting could be enhanced by not rotating the head and not displacing it, by closing one eye, and by avoiding any scene with motion. I recognized even then that the normal field of view of an ocular orbit is continually changing and that an arrested pattern is exceptional.

My comparison of the visual field to a perspective painting, although guarded, now seems to me a serious mistake. No one ever saw the world as a flat patchwork of colors — no infant, no cataract patient, and not even Bishop Berkeley or Baron von Helmholtz, who believed firmly that the cues for depth were learned. The notion of a patchwork of colors comes from the art of painting, not from any unbiased description of visual experience. What one becomes aware of by holding still, closing one eye, and observing a frozen scene are not visual sensations but only the surfaces of the world that are viewed now from here. They are not flat or depthless but simply unhidden. One’s attention is called to the fact of occlusion, not to the pseudofact of the third dimension. I notice the surfaces that face me, and what I face, and thus where I am. The attitude might be called introspective or subjective, but it is actually a reciprocal, two-way attitude, not a looking inward…

The young child learning to draw has long interested both psychologists and artists. When he first draws a man or a truck or a table, I suggest, he depicts the invariants that he has learned to notice. He does not draw a patchwork perspective, for he never had the experience of a patchwork. He may not yet draw in edge perspective because he has not noticed it. Hence, he may draw a table with a rectangular top and four legs at the corners because those are the invariant features of the table he has noticed. This is a better explanation than saying he draws what he knows about the table, his concept, instead of what he sees of the table, his sensation.



  1. It seems that the ramifications of this are incredibly intense. I shall have to re-read it, because my mind is having a hard time focusing..but wow.


    Comment by Jennifer Stuart — 19 November 2012 @ 7:56 pm

  2. It is an awfully long excerpt, isn’t it? But the more I read in the chapter the more new interesting stuff I found worth repeating. Gibson is kind of a hot item these days, even though this, probably his most influential book, is over 30 years old, and he died the year it was published. Most of the book is about direct perception of the physical environment, but this chapter and the next are about looking at pictures and movies, which is something I’d been thinking about lately.


    Comment by ktismatics — 19 November 2012 @ 9:35 pm

  3. Hmmm… I too have been strongly influenced by Gibson. That he’s hot THESE days, WOW! What’s strange is that, in a way, at core he’s very very Old School. In a (peculiar) sense. Like the behaviorists, he didn’t believe in mental stuff. And so he looked for the properties of the optical flow. And he became avant-garde by paying close attention to those properties.


    Comment by Bill Benzon — 21 November 2012 @ 1:00 pm

  4. Right — Gibson is a convergence of realism, emphasizing the invariant properties and “affordances” of the world outside the head, along with the computational theory of mind that’s central to contemporary neuroscience. I would like to have included one of the quirky illustrations from his book in this post but I couldn’t find any via casual internet browsing.


    Comment by ktismatics — 21 November 2012 @ 8:01 pm

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