Facial Identification in Observers with Colour-Grapheme Synaesthesia

Synaesthesia between colours and graphemes is often reported as one of the most common forms cross modal perception [Colizolo et al, 2012, PLoS ONE, 7(6), e39799]. In this particular synesthetic sub-type the perception of a letterform is followed by an additional experience of a colour quality. Both colour [McKeefry and Zeki, 1997, Brain, 120(12), 2229–2242] and visual word forms [McCandliss et al, 2003, Trends in Cognitive Sciences, 7(7), 293–299] have previously been linked to the fusiform gyrus. By being neighbouring functions speculations of cross wiring between the areas have been suggested as an explanation of a neural substrate of synaesthesia. The present study does not have a strong point on this view. However, as the fusiform gyrus also have been proposed to play a crucial role in the processing of facial features for identification [e.g. Kanwisher et al, 1997, The Journal of Neuroscience, 17(11), 4302–4311], increased colour-word form representations in observers with colour-grapheme synaesthesia may affect facial identification in people with synaesthesia. This study investigates the ability to process facial features for identification in observers with colour-grapheme synaesthesia. Preliminary data suggest that observers with colour-grapheme synaesthesia have a decreased ability to identify other people from facial cues.