Social reward processing in individuals with autism spectrum disorder: A systematic review of the social motivation hypothesis

Background: There is increasing empirical research examining the social motivation hypothesis, which posits that social deficits in autism spectrum disorder (ASD) are caused by underlying neural abnormalities in processing the reward value of social stimuli. Method The present systematic review examines social reward processing in individuals with ASD. This review focuses on the experimental procedures employed across studies and their potential impact on findings regarding the social motivation hypothesis. Twenty-seven studies met the specified inclusion criteria. Results: Fifteen studies found evidence supporting the social motivation hypothesis; whereas, 12 studies found contradictory evidence. Most studies used pictures of faces as social stimuli and money as comparison nonsocial stimuli. Studies examining certain reward subtypes (e.g., reward learning) consistently supported the hypothesis; whereas, studies examining other reward subtypes (e.g., effort valuation) consistently did not support the hypothesis. Otherwise, methodological approaches varied considerably across studies. Conclusion: The current empirical literature on the social motivation hypothesis is mixed, but findings suggest that examining specific sub-dimensions of reward processing may be important to clarify deficits in ASD. It is unclear whether inconsistency in findings is due to methodological limitations. As the literature stands, findings across studies support deficits in reward processing for both social and nonsocial rewards or individual differences in social reward processing. Interestingly, included articles cite few previously published studies on this topic, likely contributing to inconsistency in experimental designs and findings. Comparison across methodological approaches is warranted to help account for contrasting findings and determine the utility of the social motivation hypothesis given mixed evidence.