FAA Office of Aerospace Medicine
Civil Aerospace Medical Institute

Report No: DOT/FAA/AM-62/15

Title and Subtitle: The visual perception of size and distance

Report Date: July 1962

Authors: Gogel WC

Abstract: The perception of absolute distance has been assumed to be important in the perception of the size of objects and the depth between them. A different hypothesis is proposed. It is asserted that perceived relative size and distance are the primary psychological phenomena, with perceived absolute distance derived from the perceptual summing of perceived relative depths. In agreement with this point-of-view, it is stressed that relative, rather than absolute retinal extents, are the determiners of visually perceived extents.

A principle called the adjacency principle is identified as perceptually organizing the relative retinal stimuli. This principle states that the apparent size or position of any objects in the field-of-view is determined by whatever size or distance cues occur between it and adjacent objects. Some evidence for the adjacency principle is discussed and some consequences of the principle are considered.

Key Words: vision, perception, size, depth, adjacency principle

No. of Pages: 21