Why September is blue, and society tastes of onions: Mechanisms of linguistically triggered synaesthesia
People with synaesthesia involuntarily experience certain percepts (e.g., taste, colour) when engaged in perceptual or cognitive activities (e.g. reading, listening to music) that would not elicit that response in non-synaesthetic people. For example, colours may be experienced in response to spoken words (Marks, 1975) and shapes may be experienced in response to taste (Cytowic, 1993; Cytowic & Wood, 1982). The aim of my research is to understand the cognitive and developmental basis of synaesthesia and what, if anything, this might tell us about the ordinary functioning of memory and language. I describe an unusual case of developmental synaesthesia, in which speech sounds induce an involuntary sensation of taste that is subjectively located in the mouth (Ward & Simner, 2003). Our subject, JIW, shows a highly structured, non-random relationship between particular combinations of phonemes and the resultant taste, and this is influenced by a number of fine-grain linguistic properties. Functional neuroimaging studies of JIW (by David Parslow and colleagues) support the genuineness of the case, as does JIW’s consistency over time. Our results suggest that JIW’s synaesthesia does not simply reflect innate connections from one perceptual system to another, but that it can be mediated by a symbolic/conceptual level of representation. I describe findings from two further studies (Simner, 2003, Ward, Simner & Auyeung, 2003) which compare two different profiles of synaesthesia: word-colour and word-taste. It is argued that different cognitive mechanisms are responsible for the synaesthetic percepts in each group, and that these might inform us of the functioning of ordinary language comprehension.