Attached-shadow orientation perceived as depth by chickens reared in an environment illuminated from below.

Abstract

The depth perception of 10 leghorn chickens reared in cages illuminated from below was tested using photographed dents with shadow orientation the relevant cue. Ss assumed an overhead source of illumination seeing dents shaded below and above as convex and concave, respectively. There appears to be an innate perceptual parameter corresponding to an overhead source of illumination in terms of which orientation of attached shadow is interpreted as depth. (PsycINFO Database Record (c) 2006 APA, all rights reserved)