Face-Processing Differences Present in Grapheme-Color Synesthetes

Grapheme-color synesthesia is a heterogeneous neurological phenomenon whereby the experience of a grapheme automatically and involuntarily elicits an experience of color. While the majority of synesthesia research has focused on inducer-specific influences of synesthetic associations, more recent efforts have examined potential broader differences. Based on spontaneous reports from synesthetes detailing problems with face recognition, in conjunction with the geographical proximity of neurological regions relevant to both synesthesia and face processing, we sought to examine whether synesthetes demonstrated atypical face-processing abilities. A total of 16 grapheme-color synesthetes and 16 age-and-gender matched controls (±3 years) completed the Cambridge Face Memory Test (CFMT; Duchaine & Nakayama, 2006) of face memory, the Vanderbilt Holistic Face Processing Task (VHPT-F; Richler, Floyd, & Gauthier, 2014) of holistic face processing, as well as a standardized self-report questionnaire the Faces and Emotions Questionnaire (Freeman, Palermo, & Brock, 2015). The results revealed significantly poorer performance in synesthete's ability to recognize faces in the CFMT that was driven by a reduction in upright advantage. Results also revealed a significant reduction in overall accuracy on the VHPT-F for synesthetes, who despite this displayed a comparable holistic processing advantage compared to matched controls. Finally, synesthetes also rated themselves as significantly worse at face recognition. We suggest that this pattern may reflect differences in the development of individualized perceptual strategies.