Abstract

The study of synaesthesia has moved from single case studies to group comparisons over the last decades. These endeavours have brought about detailed knowledge on the phenomenology of synaesthesia across its range of different variants, and have provided numerous cognitive behavioural paradigms with which to test for "genuine" synaesthesia. Researchers have begun to group synaesthetes into ever more sub-groups depending on i) which senses are affected and ii) the way synaesthesia is experienced. In the latter case, an influential distinction concerns the separation of synaesthetes into projector and associator synaesthetes. Subsequent studies reported inconsistencies with which individuals described their purportedly associated versus projected status. For example, some synaesthetes categorised themselves in different ways when asked on two different occasions. This inconsistency may not reflect an unstable synaesthetic experience, but rather, a problem with methodology, because synaesthetes are often asked to verbalise what is essentially a visual phenomenon. We argue that illustrations are a superior means to properly demonstrate individual differences in the synaesthetic experience. This argument is based on a recent study in which participants were more reliably categorized into projector and associator categories when using an illustrated, rather than a purely verbal synaesthesia questionnaire. After reporting these study details, we conclude that future studies testing individual differences in synaesthesia should use illustrations when inquiring about the subjective synaesthetic experience of their participants.