“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. He proposed the multi-process theory, which explains mirror reversal in terms of different combinations of three underlying principles (one optical and two psychological). This article reports three experiments designed to test this theory. 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 it as a single phenomenon, the results of the experiments confirmed that the three kinds of mirror reversal must be distinguished. The results also confirmed a variety of predictions derived from the assumptions of the multi-process theory. 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.
- Psycho-Optical Explanation of Mirror Reversal; A Further Experimental Investigation
- Yohtaro TAKANO [高野, 陽太郎] - University of Tokyo, Graduate School of Humanities and Sociology
- Hayao Nakayama Foundation for Science & Technology and Culture (Japan, Tokyo)
- Psychology
- English
- Preprint
- 2026/06/30