Toying with the moon illusion.

Journal Article (Journal Article)

We propose that the correct interpretation of the moon illusion is that the zenith moon appears small, not that the horizon moon appears large. This illusion is caused by the visual gap between the observer and the overhead moon. Because of the gap, the observer has no or little optical information about the distance of the moon. This results in empty field myopia where the moon is neurally, although not necessarily cognitively, processed as being at about arm's length. When the moon is seen on the horizon, there usually is optical information about distance. That results in reduced accommodation, and so the moon is processed as at a greater distance. Consistent with the size-distance-invariance hypothesis, the moon is then judged as large. This is a specific example of the more general fact that all distant objects appear small in the absence of a stimulus for accommodation to be distant. This outcome produces the toy illusion.

Full Text

Duke Authors

Cited Authors

  • Lockhead, GR; Wolbarsht, ML

Published Date

  • August 1991

Published In

Volume / Issue

  • 30 / 24

Start / End Page

  • 3504 - 3507

PubMed ID

  • 20706418

Electronic International Standard Serial Number (EISSN)

  • 1539-4522

International Standard Serial Number (ISSN)

  • 1559-128X

Digital Object Identifier (DOI)

  • 10.1364/ao.30.003504


  • eng