Perceived depth as a function of relative height under three background conditions.

The hypothesis was proposed that the perceived depth, which results from the relative height cue, depends on "optical adjacency." A 3 X 3 factorial experiment was conducted to examine this hypothesis. The 2 factors were vertical separation (3.5, 5.5, or 7.5 in.) and background conditions (0 background, outline background without surface texture, or textured background). Verbal estimates of the depth between pairs of frontal parallel points were obtained under the 9 conditions. In 1 experiment, the backgrounds simulated a floor surface; in another, the backgrounds simulated a ceiling surface. Results in both experiments were comparable. Both main effects, separation and background, and the interaction effect were significant. All the effects were in the direction predicted by the optical adjacency hypothesis. (PsycINFO Database Record (c) 2006 APA, all rights reserved)