Samantha C Lee¹ (samanthalee@unr.edu), Lars Strother¹; ¹University of Nevada, Reno

Our visual system allows us to rapidly and effortlessly perceive identity-related face information (e.g., sex and age) as well as non-identity information (e.g., emotional expression). We used fMRI multivariate pattern analysis (MVPA) to study how both types of information are represented neurally. Of particular interest in our study was whether the neural representation of identity-related and non-identity information was similarly lateralized in fusiform cortex (FC). Many studies have reported right-lateralized representation of face identity information, but some recent studies have refuted this. Other fMRI studies have reported left-lateralized representation of categorical face information (e.g., sex; Zhou & Strother, VSS 2018). We wondered if other types of face information would also exhibit left-lateralized representation in FC, and whether this would be limited to identity-related face information (i.e., in addition to sex) or not. Observers in our experiment performed a one-back task while viewing 16 different faces comprising four binary categories: (1) two distinct (unfamiliar) identities; (2) sex (female/male); (3) age (old/young); and (4) emotional expression (happy/sad). Our method enabled us to determine whether all four categories could be decoded in FC and the degree to which underlying representations might be lateralized. We found that all four categories were decodable in FC but exhibited different patterns of laterality. Whereas left-lateralization was abundant (i.e., occurred for various categories and category combinations), right-lateralized decoding only occurred for age (or age combined with other categories). Emotional expression decoding was not associated with consistently lateralized representations. Our results suggest that left-lateralized face representation can be revealed by creating binary categorical face information. Nevertheless, right-lateralized representation of identity-related information can occur even when such information is treated categorically (despite being continuous) within our set of face stimuli. Our findings highlight the need for further research into the relationship between laterality in FC and categorical face perception.

Acknowledgements: This work was supported by the National Institute of General Medical Sciences of the National Institutes of Health under grant number P30 GM145646.