Perception of the standard and the reversed Müller-Lyer figures in pigeons (Columba livia) and humans (Homo sapiens)

Noriyuki Nakamura*, Kazuo Fujita, Tomokazu Ushitani, Hiromitsu Miyata

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

52 Citations (Scopus)


The authors compared perception of the standard and reversed Müller-Lyer figures between pigeons (Columbia livia) and humans (Homo sapiens). In Experiment 1, pigeons learned to classify 6 lengths of target lines into "long" and "short" categories by pecking 2 keys on the monitor, ignoring the 2 brackets so placed that they would not induce an illusion. In the test that followed, all 3 birds chose the "long" key more frequently for the standard Müller-Lyer figures with inward-pointing brackets (><) than for the figures with outward-pointing brackets (<>). The subjects' responses were accountable by neither overall lengths of the figures nor horizontal gaps between the 2 brackets. For the reversed figures, effects of the brackets were absent. These results suggested that the pigeons perceived the standard Müller-Lyer illusion but not the reversed one. Experiment 2 confirmed that humans perceived both types of the illusion. Pigeons and humans may perceive the same illusory figures in different ways.

Original languageEnglish
Pages (from-to)252-261
Number of pages10
JournalJournal of Comparative Psychology
Issue number3
Publication statusPublished - 2006 Aug 1
Externally publishedYes


  • Geometrical illusions
  • Humans
  • Müller-Lyer illusion
  • Pigeons

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Psychology (miscellaneous)


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