The moon illusion: Kaufman and Rock's (1962) apparent‐distance theory reconsidered1

Abstract

Abstract: In the present study, Kaufman and Rock's (1962) well‐known study on the moon illusion was reexamined in light of findings reported after its publication. Kaufman and Rock claimed that the visible terrain is essential for the moon illusion to occur. However, the moon illusion can be obtained in complete darkness, and the viewing angle coupled with binocular viewing was found to have a great contribution to the illusion. Thus, Holway and Boring's (1940) and Taylor and Boring's (1942) findings, which Kaufman and Rock had discredited, were partly supported. A drastic change in the perceived distance of the simulated moon was found to induce only a small change in its apparent size. All of these findings disagree with the apparent‐distance theory for the moon illusion. Several other studies have also suggested an involvement of the oculomotor system in the moon illusion. Even if the visual surround (terrain) contributes to the moon illusion as reported by Kaufman and Rock, this contribution is likely to be mediated by the state of the oculomotor system, not by a size‐distance invariance mechanism, or size constancy scaling.