Abstract
Grapheme colour synaesthesia is a heterogeneous phenomenon in a small subset of otherwise neurotypical individuals for whom experience of a grapheme automatically and involuntarily elicits an experience of colour. One theory describing why people develop synaesthesia states that it occurs in response to challenging learning tasks (Watson et al 2014). That is, the main purpose of synaesthesia is to act as an aid to perceptual and conceptual understanding of complex categorical learning challenges. Considering the wide range of complex categorical information we need to process and organise, both sensory and cognitively, it may be the case that atypical categorisation techniques adopted by synesthetes are not limited to the inducer stimulus, but apply to a wider range of categorised items. Based on this theoretical proposal, in conjunction with anecdotal reports from synesthetes detailing problems with face recognition, we explored the possibility that difficulties in face recognition may be a characteristic of grapheme-colour synesthesia. Synesthetes were recruited together with age-and-gender matched controls. All observers completed a battery consisting of the Cambridge Face Memory Test (Duchaine & Nakayama, 2006) a test of face recognition, the Vanderbilt Holistic Face Processing Test (Richler, Floyd & Gauthier, 2014) a test of holistic face processing, as well as the Faces and Emotion Questionnaire (Freeman, Palermo, & Brock, 2015). The results seem to indicate that observers with grapheme colour synaesthesia do in fact have an abnormal processing of face information, which gains further support from previous findings where Sørensen (2013) used the Cambridge Face Perception Test (Duchaine, Germine, & Nakayama, 2007) to explore a similar question.