The effect of refractive error on size constancy and shape constancy.

The effect of refractive error was determined for both size constancy and shape constancy. Although an error of 1.5 diopters reduces shape constancy, 3.0 diopters of blur had no effect on size constancy. The results are discussed in terms of the multiple mechanisms subserving the perceptual constancies. The importance of cues from the peripheral visual fields for size constancy and the role of foveally mediated texture and stereopsis cues for shape constancy are emphasized.