A comparison of lexical-gustatory and grapheme-colour synaesthesia

This study compares two different profiles of synaesthesia. One group (N = 7) experiences synaesthetic colour and the other (N = 7) experiences taste. Both groups are significantly more consistent over time than control subjects asked to generate analogous associations. For the colour synaesthetes, almost every word elicits a colour photism and there are systematic relationships between the colours generated by words and those generated by graphemes within the word (hence "grapheme-colour" synaesthesia). For the taste synaesthetes, by contrast, some words elicit no synaesthesia at all, and in those words that do, there is no relationship between the taste attributed to the word and the taste attributed to component graphemes. Word frequency and lexicality (word vs. nonword) appear to be critical in determining the presence of synaesthesia in this group (hence "lexical-gustatory" synaesthesia). Moreover, there are strong phonological links (e.g., cinema tastes of "cinnamon rolls") suggesting that the synaesthetic associations have been influenced by vocabulary knowledge from the semantic category of food. It is argued that different cognitive mechanisms are responsible for the synaesthesia in each group, which may reflect, at least in part, the different geographical locations of the affected perceptual centres in the brain.