Asymmetry in 3-D perceptual organization: ground-like surface superior to ceiling-like surface.

Attneave (1954) and Barlow (1961) proposed that the visual system might increase efficiency of representation by preferentially encoding spatiotemporally redundant patterns of the external world. The present experiments tested the application of this principle to three-dimensional (3-D) perceptual organization, capitalizing on the ecological constraint that human observers must frequently interact with objects arranged on the ground or on a surface parallel to it (Gibson, 1950). Observers performed a task that required them to perceptually segregate and search multiple items distributed in depth and embedded within a larger, 3-D array of distractors. Stimulus displays were organized to globally recede top-away in depth, as if attached to an underlying ground-like surface, or bottom-away, as if attached to an overhanging ceiling-like surface; ground-like and ceiling-like displays differed only in the direction of disparity gradient within the displays. Primary findings revealed superior performance with ground-like displays, suggesting that spatially and stereoscopically distributed items are more easily organized to represent an ecologically representative pattern, even when no inherent physical regularities favor that pattern.