Seeking Reward in Restricted Interests
Restricted and repetitive behaviors and interests (RRBIs) represent one of the defining characteristics of autism spectrum disorder (ASD). RRBIs frequently involve non-social items, like trains, favorite activities, or video games. While many brain imaging studies on ASD exist, most have focused on social communication and few have investigated the brain’s activity and processing during RRBIs.
Working in tandem with social difficulties, RRBIs may draw individuals with ASD away from interacting with others. This pull away from social interactions may lead to fewer opportunities to learn and practice social communication skills. The social motivation hypothesis of autism proposes that from early in life, individuals on the spectrum find social rewards- for example, a parent or teacher smiling when a child hands them a toy or answers a question- less rewarding than neurotypical people. According to the social motivation hypothesis, this weakened response to social information may represent a critical difference during very early development that can lead to a negative cycle of missing out on social interactions and social learning. CAR researchers recently published a brain imaging study that provides new empirical evidence supporting the social motivation hypothesis. The research, published in Molecular Autism, also suggests the hypothesis should be broadened to include both social interest and non-social RRBIs. The authors of the study suggest that future research should investigate how the brain’s reward system responds to social and non-social stimuli.
Using the social motivation hypothesis as a framework, researchers from Children’s Hospital of Philadelphia set out to understand how the reward center in the brain reacts to RRBIs in contrast to social engagements. The study recruited 39 youth with ASD and 22 without ASD to participate in functional MRI brain scans while completing a task with both social rewards (viewing video clips of people smiling and giving a ‘thumbs up’ after a correct response) and a non-social rewards tailored to each individual’s primary interest or hobby (viewing video clips of a person’s favorite video game or movie after a correct response).
The results of the study confirmed that for youth with ASD, the brain’s reward system showed reduced activity in relation to social rewards, when compared to the youth without ASD. Researchers also found that youth with ASD showed a greater reward response to video clips related to their own intense interests, compared to the youth without ASD. Intense interests included video games, music, movies/television shows, and local sports teams. Furthermore, children with ASD who had the most activation in the reward system for interests over social rewards were rated by their parents as having more severe ASD symptoms.
Findings from this study were combined with 12 other studies in a recent meta-analysis of fMRI studies of autism, which showed atypical processing of all kinds of rewards, not just social rewards. This meta-analysis confirms that the social motivation hypothesis should be broadened to consider both social and non-social rewards may be processed differently in the brains of people with ASD.
Senior author and researcher at the Center for Autism Research at CHOP, Dr. Benjamin Yerys, commented on the findings, “Our findings, along with other recent findings, suggest the social difficulties seen in autism spectrum disorders may result from finding social interactions less enjoyable than personal interests, which leads to less motivation to seek out and learn from social encounters”. Clinically these findings translate into using interventions that incorporate ways to help individuals with ASD have positive social experiences that engage their reward center in combination with building social skills.