Copyright © 1999 Massachusetts Institute of Technology
In his last book, The Ecological Approach to Visual Perception, James Gibson (1904-1979) concluded with a plea that the terms and concepts of his theory "...never shackle thought as the old terms and concepts have!" He was referring to the framework of traditional perception, as was reflected, for example, in the classical problem of space perception Bishop Berkeley posed more than three hundred years ago (Berkeley 1963). How is it possible to perceive three-dimensional space when the input to our senses is a two-dimensional retinal surface in the case of vision, or a skin surface in the case of touch? Logically, it seemed this inadequate stimulation had to be supplemented somehow to account for our ordinary perception of a three-dimensional world. There have been two general proposals for the nature of this supplementation. An empiricist proposal, advocated by Berkeley himself, based the supplementation in the prior experience of the individual. The alternative nativist proposal based the supplementation in the innate functioning of the mental apparatus which intrinsically imposes a three-dimensional structure on two-dimensional stimulation. These two alternatives in only slightly modified forms persist to this day.
Gibson challenged Berkeley's initial assumption, asserting that there is indeed sufficient information available to observers for perceiving a three-dimensional world. It does not have to be supplemented from our past experience or from our innate mental operations. Gibson's refutation of the traditional formulation depended on confirming the hypothesis that information is sufficient to account for what we perceive. He argued that the traditional physical analysis of energy available to our senses (rays of light and sound waves) is the wrong level of analysis for perceiving organisms with mobile eyes in mobile heads who look and walk around. Rather, light in ambient arrays (as opposed to radiant light) is structured by, and fully specifies, its sources in the objects and events of the world we perceive. He showed that if the entire structure of the optic array at any point in space were examined, rather than punctate stimuli impinging on the retina, the information available is exceedingly rich. Moreover it specifies important features of the environment. Thus textured optic arrays specify surfaces, gradients of texture specify slanted or receding surfaces, changing patterns in the structure are specific to particular types of object and observer movement, and so on.
Two implications of Gibson's reformulation need to be emphasized. First, patterns of stimulation change when an observing organism is active. The very act of moving makes information available. Gibson showed that the transformations in the optic array sampled by a moving observer simultaneously specify the path of locomotion (perspective structure) and the stable environment (invariant structure). The traditional formulation of perception involves a passive observer with stimulation imposed by the natural physical world or by a psychological experimenter; either observer or object movement is a complication. Gibson emphasized the active nature of perceiving, and the idea that movement is essential. Second, in Gibson's formulation perception is of properties that are relevant to an organism's being in contact with its environment: things like surfaces and changes in surface layout, places that enclose, paths that are open for mobility, objects approaching or receding, and so on. In the traditional Berkeley perspective perception is of abstract three-dimensional space. For Gibson abstract three- dimensional space is a conceptual achievement. Perception is concerned with guiding behavior in a populated and cluttered environment.
Gibson's emphasis on the functional aspects of perception had roots in his work on pilot selection and training in the Army Air Force during World War II (Gibson 1947). This functional emphasis was developed most thoroughly in his last book, where he presented his ecological approach (Gibson 1979). The first section of the book included an analysis of the physical world at a level ecologically relevant to the activity of a perceiving organism. This provided a taxonomy of the features that are perceived and an analysis of how the physical world structures light so as to provide the information for the meaningful properties to be perceived.
Gibson's ecological perspective emphasizes both the environment/organism mutuality of perception and its intrinsic meaningfulness. This emphasis has the radical implication of breaking down the subject/object distinction pervasive in Western philosophy and psychology as well as solving the psychological riddle of how perception is meaningful. The meaningfulness of perception is reflected in his concept of affordance which is currently the source of some controversy. AFFORDANCES are the properties of the environment, taken with reference to creatures living in it, that make possible or inhibit various kinds of activity: surfaces of a certain height, size, and inclination afford sitting on by humans, those of a different height and size afford stepping up on, objects moving at a certain speed afford catching, and so forth. For Gibson, perception of these possibilities for action are primary, and they are specified by information in the optic array.
The concept of affordance is implicated in another controversial concept of Gibson's formulation, that of direct perception. Gibson argued that perception is direct in the sense that perceiving a property, for instance an affordance, is based on detection of the information specifying that property. (For affordances the meaning is appreciated in the very detection of the information.) Critics of his theory interpret direct perception as implying that perception is automatic and argue that it is easy to find examples where it is not. This is a misunderstanding. Direct perception does not imply automaticity, rather the processes involved are different from the traditional ones; they are not association or computation but exploration, detection of invariant relations, and perceptual learning.
Many of Gibson's empirical discoveries were incorporated into mainstream theories of perception during his lifetime. From early in his career adaptation to prolonged inspection of curved and tilted lines (e.g., Gibson 1937) became a prototype of subsequent research concerned with perceptual and perceptual-motor adaptation to visual-motor rearrangements. TEXTURE gradients have long been accepted as one of the "cues" of DEPTH PERCEPTION. The investigation of the use of motion transformations for guiding locomotion and the analysis of active perception in general, particularly in computer science, are very active research areas. Gibson's theoretical influence has been extended by many of his former colleagues and students whose research is motivated by his ecological framework. Many groups and research problems illustrate this influence: Lee (1980), Warren, Morris, and Kalish (1988), and others have investigated the geometric nature of motion-generated information available for the guidance of locomotion. Turvey, Shaw, and others (e.g., Turvey et al. 1981) have integrated Gibson's ideas with those of Nicolai Bernshtein, the Russian action physiologist, in investigations and analyses of both visual and haptic perception. Edward Reed has extended his views to what he terms ecological philosophy, described in three recent books (Reed 1996a, 1996b, 1997). Gibson's closest and most influential colleague was his wife, Eleanor Jack Gibson, who has elaborated a theory of perceptual learning and development, complementary to his theory of perception (E. J. Gibson 1969). Most recently she and her colleagues (e.g., Adolph, Eppler, and Gibson 1993; A. D. Pick 1997; Walker-Andrews 1988; and others) have been applying the concept of affordance in the study of PERCEPTUAL DEVELOPMENT in a way that simultaneously refines the concept itself. Such investigations have shown the promise and utility of Gibson's radical formulation. Such success will really be complete when it permits and encourages further development of his theoretical concepts without the shackling which he feared.
This article was to have been written by Gibson's close friend and younger colleague, Edward Reed. His untimely death in February, 1997, has deprived the field of a brilliant and humane scholar.
Adolph, K. E., M. A. Eppler, and E. J. Gibson. (1993). Development of perception of affordances. In C. Rovee-Collier and L. P. Lipsitt, Eds., Advances in Infancy Research, vol. 8. Norwood, NJ: Ablex, pp. 51-98.
Berkeley, G. (1709/1963). An essay towards a new theory of vision. In C. Turbayne, Ed., Berkeley: Works on Vision. Indianapolis: Bobbs-Merrill.
Gibson, E. J. (1969). Principles of Perceptual Learning and Development. New York: Appleton-Century-Crofts.
Gibson, J. J. (1937). Adaptation with negative after-effect. Psychological Review 44:222-244.
Gibson, J. J. (1947). Motion picture testing and research. Aviation Psychology Research Reports No. 7. Washington, DC: U.S. Government Printing Office.
Gibson, J. J. (1979). The Ecological Approach to Visual Perception. Boston: Houghton Mifflin.
Lee, D. N. (1980). The optic flow field: the foundation of vision. Philosophical Transactions of the Royal Society, London Series B, 290:169-179.
Pick, A. D. (1997). Perceptual learning, categorizing, and cognitive development. In C. Dent-Read and P. Zukow-Goldring, Eds., Evolving Explanations of Development. Washington, DC: American Psychological Association, pp. 335-370.
Reed, E. S. (1996a). Encountering the World. New York: Oxford University Press.
Reed, E. S. (1996b). The Necessity of Experience. New Haven: Yale University Press.
Reed, E. S. (1997). From Soul to Mind. The Emergence of Psychology, from Erasmus Darwin to William James. New Haven: Yale University Press.
Turvey, M. T., R. E. Shaw, E. S. Reed, and W. M. Mace. (1981). Ecological laws of perceiving and acting: in reply to Fodor and Pylyshyn (1981). Cognition 9:237-304.
Walker-Andrews, A. S. (1988). Infant perception of the affordances of expressive behaviors. In L. P. Lipsitt and C. Rovee-Collier, Eds., Advances in Infancy, vol. 5. Norwood, NJ: Ablex, pp. 173-221.
Warren, W. H., M. W. Morris, and M. Kalish. (1988). Perception of translation heading from optical flow. Journal of Experimental Psychology: Human Perception and Performance 14:646-660.
Gibson, J. J. (1950). The Perception of the Visual World. Boston: Houghton Mifflin.
Gibson, J. J. (1968). The Senses Considered as Perceptual Systems. London: Allen and Unwin.
Michaels, C., and C. Carello. (1981). Direct Perception. New York: Prentice-Hall.
Reed, E. S. (1988). James J. Gibson and the Psychology of Perception. New Haven: Yale University Press.
Reed, E. S., and R. K. Jones, Eds. (1982). Reasons for Realism: Selected Essays of James J. Gibson. Hillsdale, NJ: Erlbaum .
Copyright © 1999 Massachusetts Institute of Technology