Victor Navarro, University of Iowa
ABSTRACT: When animals discriminate between stimuli that vary along multiple dimensions, sometimes dimensions interact with each other to affect perception. It has been shown that humans perceive circle size and the orientation of its drawn diameter as separable dimensions; the judgment of one dimension was not affected by variation in the other. However, they perceive the width and height of rectangles as integral; the judgment of one dimension was affected by variation in the other. Following previous findings in non-human animals, we studied how pigeons process three visual dimensions: the height, width, and length of a cube. We trained pigeons in both go/no-go and simultaneous discrimination tasks. Their generalization data were fitted using Soto & Wasserman’s (2010) spatial model, optimizing for Minkowski’s distance metric. Our results showed that some, but not all pigeons perceived the dimensions as integral (Minkowski’s r = 2). These findings constitute the first demonstration of integrality along three visual dimensions in a non-human species.