The biological bases of colour categorisation: From goldfish to the human brain.

How are colour categories related to perception and language? To answer this question, we review research on the neural correlates of colour categories, and categorical responses in preverbal infants and non-human animals. With respect to language, the reviewed findings suggest that colour categorisation often involves automatic language processing. At the same time, evidence from non-human animals, infants, and patients with brain lesions indicates that colour categorisation may also occur in the absence of language. Concerning perception, there is little convincing evidence that the bottom-up processes of colour perception are the origin of colour categories. Instead, colour categorisation might simply build upon the continuous colour perception and interact with perception through the direction of attention to colour differences that are relevant to categorisation. We make three suggestions for future research. First, future research in all areas requires methodological improvements, in particular in stimulus control. Second, future research should overcome the universalist-realist debate and go beyond a simple contrast between perception and language. Third, the link between object colours and colour categories provides an alternative approach that might reveal the ecological origin of colour categories. The ecological approach promises establishing evolutionary and developmental continuity between categorical responses in non-human animals, infants and adult humans.