The inter-association between face processing, intelligence, and autistic-like nonverbal communication

The degree to which face processing abilities inter-relate, and associate with general intelligence, remains a contentious issue. Furthermore, poorer face processing abilities may be a result of reduced social interest associated with higher levels of trait-autism, consistent with the social motivation theory of autism. However, the association between multiple dimensions of face processing (i.e., a general face factor) and trait-autism, specifically autistic-like nonverbal communication, has not been estimated. Consequently, we administered four face processing ability tests (assessing face detection, the perception and memory of face identity, and expression recognition), four cognitive ability tests, and the Autism Quotient to a sample of 253 general community adults. Based on latent variable modelling, we identified a general face processing ability factor (f), and it was positively associated with general intelligence (g; λ = .48). We conclude that face processing abilities may be a candidate ability within the Cattell-Horn-Carroll model of intelligence. Moreover, face memory was positively associated with g (β = .31). We discuss the possibility of developmental prosopagnosia, i.e., deficits in face memory, being diagnosed as a learning disability. Furthermore, autistic-like nonverbal communication was a significant, negative predictor (β = -.45) of f, and g was neither a mediator nor suppressor of the effect. Finally, the unique effect between autistic-like nonverbal communication difficulties and face processing abilities, independently of intelligence, was considered in line with the social motivation theory of autism.