Overconstancy in Distance Perception as a Function of the Texture of the Stimulus Field and other Variables

Abstract

The primary aim of this investigation, inspired in part by Gibson's theory of space perception, was to study changes in distance bisections over short distances (up to 150 cm. from S) as a function of the texture of the stimulus field. The latter was systematically varied along two dimensions: the density of the texture elements and the degree of patterning in the arrangement of these elements. Panels constructed to represent these textures served as a ground over which the distance bisections were made; they were displayed in a brightly lit viewing box. A consistent bias of overconstancy was found for all textures (including a blank panel); the texture variable affected the judgments only to a very slight degree. Overconstancy rose markedly as a function of S's exposure to the task. Two subsidiary experiments showed no difference between binocular and monocular viewing, but substantial reduction in overconstancy when S's viewing height was increased The results were interpreted as reflecting the operation of a judgmental bias developing as S's perceptual frame of reference became stabilized; this frame of reference appears to operate in relative independence of stimulus variables such as those emphasized by Gibson.