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 inc rease efficiency of representation by preferentially encoding spatiotempora lly redundant patterns of the external world. The present experiments teste d the application of this principle to three-dimensional (3-D) perceptual o rganization, capitalizing on the ecological constraint that human observers must frequently interact with objects arranged on the ground or on a surfa ce parallel to it (Gibson, 1950). Observers performed a task that required them to perceptually segregate and search multiple items distributed in dep th and embedded within a larger, 3-D array of distracters. Stimulus display s 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 overh anging ceiling-like surface; ground-like and ceiling-like displays differed only in the direction of disparity gradient within the displays. Primary f indings revealed superior performance with ground-like displays, suggesting that spatially and stereoscopically distributed items are more easily orga nized to represent an ecologically representative pattern, even when no inh erent physical regularities favor that pattern.