Why Do Things Look As They Do?
The Implications of J. J. Gibson's The Ecological Approach to Visual Perception
Edward S. Reed
INTRODUCTION: GIBSON'S PROJECT
The Ecological Approach to Visual Perception (1979) was James J. Gibson's final book, representing the culmination of more than a half century's experimentation, looking and pondering by the most important student of visual perception of the twentieth century. Because Gibson combined a unique freshness of thought with a deep insight into the fundamental problems of psychology, his work continually evolved, making it difficult for even a diligent reader to be certain of having caught all the implications of any one of his writings. Gibson challenged orthodox psychology on a whole host of issues that no one else had ever considered deeply. He upset the applecart. And he did so repeatedly, often undercutting his previous most radical pronouncements with still more radical arguments and experiments. In this chapter I shall attempt to articulate some of the more fundamental implications of Gibson's last book. I shall thus say very little about how his thought developed (see Reed and Jones, 1982; and Reed, 1986a...) but a great deal about his last version of a psychology that did not accept traditional assumptions, or what he had come to call an ecological psychology. After briefly contrasting Gibson's last with his previous books, to give at least some of the developing context of his thought I proceed by discussing each section of The Ecological Approach, which provides a convenient overview of the components of ecological psychology.
In The Perception of the Visual World (1950), Gibson offered a solution to the centuries-old problem of depth perception. [p. 91] Although he eventually rejected this solution, it has become common currency among psychologists. Prior to Gibson's work, visual psychology had no plausible account of everyday depth perception, the sort of seeing required to drive a car without crashing. Nowadays Gibson's early ideas of 'texture gradients' and 'motion perspective' can be found in most textbooks on perception as explanations of 'depth' or 'space' perception, along with more classical theories of the 'cues' for depth. It is a measure of Gibson's independent thinking and rigorous standards that he did not remain satisfied with this earlier account, despite the considerable acclaim he received for it. And it is especially significant that the most telling experimental attacks on Gibson's early theory of visual space perception derived from his own laboratory (Reed, 1986a).
In The Senses Considered as Perceptual Systems (1966) Gibson offered a solution to the problem of how our several kinds of sensory experiences become transformed and integrated into cognition of the world. He rejected the fundamental assumption of all previous theories of perception, that sensations are expanded into perception by some form of mental activity. He offered instead a theory of perception as based not on sensations, but on information in stimulation. When stimulation is imposed on passive observers, sensations arise; but when active, purposeful creatures are allowed to explore stimulation they are able to detect information that is specific to environmental sources. Thus, Gibson insisted that the category of exploratory (as opposed to performatory) behaviour be recognised to enable us to understand the behavioural functioning of perceptual systems. However, Gibson's novel distinction between obtained and imposed stimulation (yielding sensations specific to sensory nerves) has been largely ignored, although his work prompted renewed interest in so-called 'sensory integration' (Mendelsohn and Haith, 1976; Mark, 1978), and in the relation of overt attention to perceiving (Neisser, 1976). In his later work Gibson continued to accept his view of the sense not as conduits to the soul or brain, but as information-seeking systems.
The Ecological Approach to Visual Perception tackled an even more difficult issue than previously. Gibson asked, 'why do things look as they do?' -echoing Koffka (1935) but giving the [p. 92] question a pragmatic twist: 'How do we see where we are in the environment? How do we see whether or not we are moving and, if we are, where are we going? How do we see what things are good for? How do we see how to do things...? (Gibson 1979, p. 1). The answer to all of these questions is straightforward, but understanding the answer (much less accepting it!) requires a willingness to dispense with many of the fundamental assumptions of western philosophy and science. We see as we do, Gibson says, because we see what the affordances for behaviour of things are on the basis of information specifying those affordances. Gibson's new solution to this old puzzle will not make much sense until one is willing to doubt that sensations are the basis of perceptions, that there are stimuli for organisms, that the brain processes or integrates or stores information, that perception without conception is blind... to list only a few of the theories Gibson rejects.
Gibson's project is certainly daunting with metaphysical and epistemological consequences as well as scientific ones. This is what is so exciting about his work: right or wrong, he tackled big problems and asked new and insightful questions. Although his answers to these questions are controversial, even someone who holds views diametrically opposed to Gibson's will appreciate his questioning of fundamental assumptions.
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Gibson says things look as they do because they afford what they do, that we have evolved so as to perceive affordances and there is optical information available specifying those affordances. This answer contrasts markedly with the traditional answer that things look as they do because that is how the mind interprets the brain movements, or because the fields of force in the brain so organise that proximal stimuli or because the brain computes the visual properties of things form retinal images.
It is very much n open question whether Gibson's new answer, or any theory along similar lines, can succeed. To be consistent, Gibson must reject most of the concepts and dichotomies of our intellectual heritage (Agassi, 1977). Such a wholesale rejection will not succeed without satisfactory rebuilding. Gibson supplied considerable empirical support for his views, but philosophers as well as scientists should question the conceptual foundations and implications of his work to see how well his rejections and replacements really work.
In this chapter I have touched on many of the issues addressed by Gibson's final ideas but I have not done justice to the depth and breadth of Gibson's project. In producing his final book, Gibson worked through American realism, pragmatism, behaviourism, phenomenology, Gestalt theory, systems theory, act psychology, evolutionary theory and ecology, sifted the wheat from the chaff and produced not a [p. 112] muddled eclecticism, but a surprisingly clear new approach. It is a new approach to all of psychology, and it has many implications for the human sciences in general.
The psychology of perception is an old science. It has not changed fundamentally since Descartes' day, although the puzzles and mysteries have deepened and darkened across the years. Gibson's ideas are surely wrong in many ways, but I venture to suggest that they are far more correct than any previous ideas, and that they are incorrect in ways which will prove to be fruitful and innovative. Above all, Gibson's ideas are new in a good way: they are not merely novel, but profoundly challenging.
Even if they prove to be wrong. Gibson's ideas will not lead to the old dead-ends and puzzles but will open up to us unexplored vistas of thought, and important new conceptual terrains. Anyone interested in perception and psychology, whether or not they agree with Gibson's arguments, will provide us with further enlightenment by heeding the advice of Gibson's final words: 'These terms and concepts are subject to revision as the ecological approach to perception becomes clear. May they never shackle thought as the old terms and concepts have!'
Gibson, J.J. (1950). The Perception of the Visual World. Boston: Houghton Mifflin.
Gibson, J.J. (1966). The Senses Considered as Perceptual Systems. Boston: Houghton Mifflin.
Introduction (pp. 1-6); "Chapter XIII: The Theory of Information Pickup" (pp. 266-286); "Chapter XIV: The Causes of Deficient Perception" (pp. 287-318).
Gibson, J.J. (1979). The Ecological Approach to Visual Perception. Boston: Houghton Mifflin.
Koffka, K. (1935). Principles of Gestalt Psychology. New York: Harcourt.
Neisser, U. (1976). Cognition and Reality. San Francisco: Freeman.
Reed, E.S. & Jones, R. (Eds.). (1982). Reasons for Realism: Selected essays of James J. Gibson. Hillsdale, NJ: Lawrence Erlbaum Assoc.
Reed, E.S. (1986). James Gibson's ecological revolution in perceptual psychology: A case study in the transformation of scientific ideas. Studies in the History and Philosophy of Science, 17, 65-99.
Reed, E.S. (1987). James Gibson's Ecological Approach to Cognition (pp. 142-173). In A. Costall & A. Still (Eds.). Cognitive Psychology in Question. Sussex: Harvester Press.
Reed, E.S. (1993). The intention to use a specific affordance: A conceptual framework for psychology (pp. 45-76). In R. Wozniak & K. Fischer (Eds.). Development in Context: Activity and Thinking in Specific Environments. Hillsdale, NJ: LEA.