Ecological Approach

Ecological psychology, as it applies to the domains of perception and perceptual development, refers to the perspective developed during a 30-year period by J. J. Gibson and Eleanor J. Gibson, and elaborated during the past two decades by their students and colleagues. The impetus for this approach grew largely from J. J. Gibson's work early in his career on several practical problems, such as how individuals control their movement when driving a car or landing a plane. These investigations led him to conclude that traditional theories of perception, and their supporting evidence mostly gathered in laboratory conditions, did not apply well to more everyday circumstances of perceiving. This entry describes major concepts in ecological optics, perceptual learning and development, and philosophical implications of ecological realism.

The adjective ecological in ecological psychology refers to two distinguishing characteristics of Gibson's approach to perception that sets it apart from more traditional theories.

1.Traditional theories of visual perception begin their analysis with consideration of patterns of stimulation on the sensory receptors (i.e., the retina), and the ensuing patterns of neural firing to sites in the brain. The starting point for an ecological approach to perception is an analysis of the environment within which a species has evolved (i.e., its econiche). The environment for terrestrial organisms is filled with substances of a wide-ranging variety, from soils and grasses to bodies of animals and water. In the case of visual perception, these substances can be perceived because of the way light from a radiant source (e.g., the sun) interacts with their surface properties (e.g., orientation to light source, texture, pigmentation). The resulting array of reflected light that has been structured by such surface properties fills the medium (the air), and this array of structured light surrounding the individual (ambient optic array) can function as potential information for perceiving. The study of how light in the medium is structured by surfaces is referred to as ecological optics. J. J. Gibson proposed that psychologists begin to consider higher-order structure in the ambient optic array of information for perceiving.

2.Traditional theories of visual perception take as their primary focus a stationary perceiver positioned at a fixed observation point. In contrast, the ecological approach takes as its primary focus the dynamic perceiver-environment relationship. What is dynamic about the perceiver-environment relationship? On the one hand, environmental conditions are not static, but change over various units of time (e.g., seconds, hours, days, seasons) requiring perceivers to keep abreast of conditions. On the other hand—and significantly—perceiving involves ongoing, exploratory actions of the individual (the functioning of perceptual systems) in the detection of stimulus information. Just as it is far easier to identify an object through active touch (manipulating the object in one's hand) than passively grasping it, perceiving through vision is facilitated by actions of the individual, such as moving the head and body in relation to objects and to the overall environmental layout.

Why do actions of the body contribute to detection of stimulus information? They produce perceived changes in the ambient optic array, and in so doing reveal that which does not change, what is invariant in the array of reflected light. (An invariant is a set of relationships among structures that do not change across transformations of those structures over time.) Invariance in the ambient array is posited to be specific to stable and persisting features of the environment. For example, if a perceiver walks around a table, certain relationships, such as the adjacent order of corners and edges, will remain invariant across successive views, displaying the specific rigid structure of this object. Actions of the various perceptual systems play an essential role in revealing invariants in the ambient array over time. Concurrently, the perceived changes in the ambient array that are generated by the perceiver's actions provide information for self-movement.

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