The adjacency principle asserts that the dominant cues in the determination of the perceived position of an object in a configuration of objects are the distance cues which occur between it and adjacent, not displaced, objects. The purpose of the present study was to apply this principle to the perception of relative depth from size cues. For this purpose, a visual situation was produced in which the perceived depth position of a playing card would differ depending upon the relative effectiveness of the size cue between this card and other cards. In agreement with the adjacency principle it was found that the size cue between adjacent cards was more effective than the size cue between displaced cards in the determination of perceived relative depth. (PsycINFO Database Record (c) 2006 APA, all rights reserved)