Psycho-Optical Explanation of Mirror Reversal

" Why do mirrors reverse left and right but not up and down? " Although this mirror reversal problem has been discussed for centuries, it still remains a puzzle. Takano (1998) found that mirror reversal is not a single phenomenon but actually a set of three distinct phenomena. This article reports three experiments designed to test this insight. Each experiment consisted of multiple tasks in which various mirror images were presented and participants judged whether they recognized any reversal in each mirror image. In some tasks, participants identified left and right for both a real object and its mirror image. Although all the other accounts of mirror reversal attempted to explain mirror reversal as a single phenomenon, the results of the experiments confirmed the insight that the three kinds of mirror reversal have to be distinguished. The results also confirmed the predictions derived from the assumption that different combinations of three underlying principles generate the three kinds of mirror reversal. Although the experimental findings can be used to disconfirm the other accounts of mirror reversal, those accounts are discussed only in passing due to space limitations.