ABSTRACT
When spectacles are worn that force the eyes to view an object with the distance cues of accommodation and convergence so altered that they correspond to a distance larger than the object's actual distance, the object, as expected, looks larger than it would without the spectacles. However, when the object is one of familiar size, it will appear to be nearer rather than farther because its large perceived size operates as a distance cue that overcomes the oculomotor cues that represent its distance as large. (For many observers a 10-or IS-diopter wedge prism suffices for such an observation. When one holds it close to one eye with base vertical and toward the bridge of one's nose and observes binocularly for 10 seconds one's other hand held 25 or 30 em from the eyes, the hand will look large and quite near.) The horizon moon provides another instance of such paradoxical perceived distance (Kaufman & Rock, 1962). Available cues for its large distance may make it look large as a result of the compensation process, but its large perceived size causes it to look nearer than the elevated moon. That observation does not raise a problem in size perception. It is important to make the distinction between registered distance and perceived distance and to accept the fact that perceived distance can depend on the perceived size of familiar objects. Failure to do so raises false problems.
