Terrestrial-passage theory: failing a test.
Terrestrial-passage theory proposes that the 'moon' and 'sky' illusions occur because observers learn to expect an elevation-dependent transformation of visual angle. The transformation accompanies daily movement through ordinary environments of fixed-altitude objects. Celestial objects display the same visual angle at all elevations, and hence are necessarily non-conforming with the ordinary transformation. On hypothesis, observers should target angular sizes to appear greater at elevation than at horizon. However, in a sample of forty-eight observers there was no significant difference between the perceived angular size of a constellation of stars at horizon and that predicted for a specific elevation. Occurrence of the illusion was not restricted to those observers who expected angular expansion. These findings fail to support the terrestrial-passage theory of the illusion.
Reed
Charles F
CF
Department of Psychology, Temple University, Philadelphia, PA 19010, USA. creed@temple.edu
Krupinski
Elizabeth A
EA
D000531:Altitude; D004215:Distance Perception; D006801:Humans; D016081:Moon; D009903:Optical Illusions; D011582:Psychological Theory; D012858:Size Perception