People cannot locate the projection of an object on the surface of a mirror.

Rebecca Lawson, University of Liverpool

People cannot veridically perceive the reflection of objects as projections on the surface of mirrors. People tried to locate an object's projection on a flat mirror. The observer stood at the opposite end of a long mirror to the experimenter. They were told to remember the location of the projection of the experimenter's face. The experimenter then moved and the observer stuck a card onto the mirror at this remembered location. The actual location was midway along the mirror between the experimenter and the observer. However, cards were placed much too close to the experimenter. Repeated testing with feedback reduced, but did not eliminate, errors. Our perception of mirrors is dominated by what appears to be visible through the mirror, not what is projected onto its surface. In contrast, if the experimenter stuck a card onto the mirror then removed it, observers remembered this physically-specified location accurately.

Cognition, (2010), 115, 336-342.