Developmental changes in understanding an illusion based on perceptual adaptation: effects of feedback.

Children and adults were exposed to an illusion created by perceptual adaptation, in which they perceived two identical bottles, held simultaneously in a different hand, as being different in weight. Prior research has shown that young children treat the perceived difference as real rather than illusory. In an initial study, feedback designed to signal the illusory nature of the weight difference led many third graders to acquire an erroneous rule. Older children and adults more often gave a correct response, although there was no clear evidence that they understood the illusion. In Study 2, confronting children with the discrepancy between the preillusion phase of the testing and the subsequent experience of an illusion helped them to infer an understanding of the illusion when the discrepancy was large. The results have implications for the development of the understanding of perceptual processes, the appearance-reality distinction, and the child's theory of mind.