The Craik-O’Brien-Cornsweet Illusion in Honeybees

Abstract

Humans perceive a low-contrast Craik-O’Brien-Cornsweet (COC) grating as being similar to, or even indiscriminable from, a squarewave grating (Fig. l), despite the fact that the spatial intensity profiles of the two patterns are very different [3]. This similarity has been attributed to processing at early stages of the visual pathway which selectively transmits edge information, followed by cortical mechanisms which “fill in” the appropriate intensities between the edges [9]. Here we find that bees behave as though they experience a similar illusion, suggesting that certain principles of visual processing are shared by insects and humans. While the visual systems of insects and humans display several differences an obvious one being that insects possess compound (multi-faceted) eyes whilst humans possess simple (single lens) eyes recent work is beginning to reveal several parallels with regard to the ways in which the two systems process visual information. For example, bees, like humans, possess trichromatic vision [ 161, are “colour-blind” with respect to the detection of motion [ 12, 131, appear to analyse pattern orientation by using orientation-tuned channels [20, 211 and even exhibit “top-down” processing with regard to the ability to detect camouflaged objects [22]. Indeed, insects even seem to experi-