The linguistic and cognitive factors associated with lexical-gustatory synesthesia: A case study

Past research on lexical-gustatory synesthesia (people who associate words with tastes) has shown that linguistic factors underlie the inducer (word)-concurrent (taste) mappings in these individuals. The developmental cognitive model envisioned by Simner and Haywood (2009), and an extension of it proposed in this paper can be used to understand these linguistic associations. The first aim of the current case study was to test these models by examining the linguistic factors associated with this type of synesthesia. The influence of lexical-gustatory synesthesia on memory was investigated using a paired-associate learning task. Further, the present case study also examined if word-pairs with same or similar tastes and word-pairs with dissimilar tastes enhanced learning relative to word pairs that had no tastes. As predicted, the findings revealed possible phonological, phonological-lexical, and lexical-semantic factors linking the inducer-concurrent pairings. These findings are in line with the developmental cognitive models of LG synesthesia. There were no effects of synesthesia on memory as demonstrated by the lack of any significant difference between the synesthete and non-synesthete controls on a paired-associate learning task. Moreover, no significant differences emerged between the "no taste" and "taste" conditions (although she performed slightly better on the "no taste" condition). Interestingly, a metamemory task (judgment-of-learning) revealed the opposite. That is, the synesthete predicted that her learning would be better in the "taste" condition when compared to the "no taste" condition. This indicates that the word-pairs, which produced tastes, could have created a "foresight bias". This is attributed to the unidirectional nature of this individual's LG synesthesia. This finding should, however, be treated with caution because it is a preliminary finding based on a single subject and needs to be corroborated with future studies on other lexical-gustatory synesthetes.