No role for colour in symmetry perception

Bilateral colour symmetry, such as that evident in a Siberian tiger’s face (Fig. 1a), is relevant to many animals1,2, including humans,. We examined the role of colour in symmetry perception by asking observers to detect colour symmetry in regular grids of coloured squares (a colour-symmetrical image has regions of the same colour located equidistantly from a vertical axis). Our results suggest, unexpectedly, that the mechanisms of symmetry perception are inherently colour-blind: although observers can verify colour symmetry, they do so only by shifting attention from one colour to the next and assessing the symmetry of regions of that colour. © 1999 Macmillan Publishers Ltd.