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ERIC Number: EJ916428
Record Type: Journal
Publication Date: 2011-Apr
Pages: 5
Abstractor: As Provided
Reference Count: 0
ISSN: ISSN-0010-0277
Pigeons Perceive a Reversed Zollner Illusion
Watanabe, Sota; Nakamura, Noriyuki; Fujita, Kazuo
Cognition, v119 n1 p137-141 Apr 2011
Pigeons are susceptible to several size and length illusions, but in some cases the bias has been shown to be opposite to that seen in humans. To further investigate how their perceptual system works, we asked how pigeons perceive orientation illusions. We used the Zollner illusion, in which parallel lines look non-parallel due to series of short crosshatches superimposed on the lines. First, we trained six birds to peck at the narrower (or wider) of the two gaps at the end of a pair of non-parallel target lines. After adapting the subjects to target lines with randomly oriented crosshatches (which result in no illusion at least to humans), we tested the pigeons' responses on randomly inserted probe trials, in which crosshatches that should induce the standard Zollner-like illusion for humans replaced the random-oriented ones. The results suggested that pigeons do perceive an illusion from Zollner figures, but in the direction opposite to that of humans. We propose that pigeons, contrary to humans, may assimilate the two lines of different orientations (each main line and crosshatch), which results in underestimation of acute angles, and this in turn may lead to a reversed Zollner illusion. Such assimilation dominance appears consistent with previous reports obtained for line length and size illusions in this species. (Contains 4 figures.)
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Publication Type: Journal Articles; Reports - Evaluative
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A