contiguity a Gestalt principle of perception, the tendency to perceive two things that happen close together in time as being related depth perception the ability to perceive the world in three dimensions monocular cues (pictorial depth cues) cues for perceiving depth based on one eye only binocular cues cues for perceiving depth based on both eyes linear perspective monocular depth perception cue, the tendency for parallel lines to appear to converge on each other. relative size monocular depth perception cue, per- ception that occurs when objects that a person expects to be of a certain size appear to be small and are, therefore, assumed to be much farther away. interposition monocular depth perception cue, the assumption that an object that appears to be blocking part of another object is in front of the second object and closer to the viewer. aerial (atmospheric) perspective monocular depth perception cue, the haziness that surrounds objects that are farther away from the viewer, c ausing the distance to be perceived as greater