Home   Publication   A horse's eye view: size and shape discrimination compared with other mammals
Tomonaga M, Kumazaki K, Camus F, Nicod S, Pereira C, Matsuzawa T (2015) A horse's eye view: size and shape discrimination compared with other mammals Biology Letters 11: 20150701
ウマの目からの眺め:ウマ、イルカ、チンパンジー、ヒトにおける図形知覚の比較

Masaki Tomonaga, Kiyonori Kumazaki, Florine Camus, Sophie Nicod, Carlos Pereira, Tetsuro Matsuzawa

A horse's eye view: size and shape discrimination compared with other mammals

Biology Letters, 11: 20150701, doi: 10.1098/rsbl.2015.0701


Abstract

Mammals have adapted to a variety of natural environments from underwater to aerial and these different adaptations have affected their specific perceptive and cognitive abilities. This study used a computer-controlled touchscreen system to examine the visual discrimination abilities of horses, particularly regarding size and shape, and compared the results with those from chimpanzee, human and dolphin studies. Horses were able to discriminate a difference of 14% in circle size but showed worse discrimination thresholds than chimpanzees and humans; these differences cannot be explained by visual acuity. Furthermore, the present findings indicate that all species use length cues rather than area cues to discriminate size. In terms of shape discrimination, horses exhibited perceptual similarities among shapes with curvatures, vertical/horizontal lines and diagonal lines, and the relative contributions of each feature to perceptual similarity in horses differed from those for chimpanzees, humans and dolphins. Horses pay more attention to local components than to global shapes.



Keywords

visual perception, horses, comparative cognition


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