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Thesis Format

Integrated Article


Doctor of Philosophy




Heerey, Erin


Previous research has shown that individuals with autism spectrum disorder (ASD) appear to learn from social and non-social rewards at different rates compared to typically developing individuals. Several hypotheses have been developed to explain these differences, including the social motivation hypothesis, the weak central coherence hypothesis and hypotheses related to probabilistic learning ability. However, in all cases, the literature shows only mixed support for these ideas. This dissertation focuses on identifying which assumptions from these hypotheses replicate and what replication successes and failures mean for the study of autism-spectrum traits within the general population.

This work takes a “spectrum” approach to autism that assumes ASD-related traits occur on a scale continuum. It therefore is designed to test the central predictions of each of these hypotheses amongst participants sampled from the general population. The use of general population samples confers the considerable advantage of allowing adequate statistical power for hypothesis tests. In addition to these hypotheses, this dissertation explores how social behavior and interaction outcomes relate to ASD-traits and task outcomes.

Interestingly, results ran contrary to many of the previous findings in the literature. Despite evidence of associations within the general population and ASD-traits, I failed to find clear associations between ASD-traits and predictions made by the Social Motivation Hypothesis, the Weak Central Coherence Hypothesis or hypotheses related to probabilistic learning ability. Despite these results, data on real social behavior and social outcomes did vary as a function of ASD-relevant traits. Specifically, the interaction partners of individuals who reported higher levels of ASD-traits experienced them as less likable and reported worse interaction quality. Additionally, individuals reporting higher levels of ASD-related traits were less expressive than those reporting fewer traits.

Overall, while predictions about ASD-traits and cognitive/motivational processes did not appear to replicate within the general population, ASD-traits do appear to be related to real-life social behavior and interaction outcomes associated. Together, these findings document subtle social behavior differences associated with ASD traits in the absence of social cognitive differences and suggest that major theories of autism may not sufficiently explain the causes of altered social behavior in those with autism-spectrum conditions.

Summary for Lay Audience

Autism spectrum disorder is a pervasive developmental disorder that deeply impacts the social lives of those diagnosed. Across the years, many hypotheses have been developed to explain how this disorder disrupts social function. This dissertation explores key predictions made by three major theories of autism: the social motivation hypothesis, the weak central coherence hypothesis and probabilistic learning hypotheses. Because research over the last decade suggests that autism traits occur on a spectrum, rather than representing a qualitative shift in function or symptoms with the presence of diagnosis, the samples in this set of studies come from the general population.

This work examines three major research questions: 1) Do autism-spectrum traits affect how people value smiles? 2) Do autism-spectrum traits affect how you perceive the world? 3) Do autism-spectrum traits affect how people learn from ambiguous environments and feedback? In addition to these questions, this dissertation also explores how social behavior and social interaction outcomes relate to autism-spectrum traits.

Interestingly, the present results were generally contrary to the predictions made by major theories. Indeed, most of the findings showed little if any effect. Additionally, the tasks in these studies, which have been theorized to underpin social function showed no clear relationship to social interaction outcomes, suggesting that social interaction skill is not related to autism traits in nearly as straightforward a fashion as previous work has claimed. Nonetheless, findings did show a clear relationship between autism-spectrum traits and social interaction outcomes, as well as social behavior. More specifically, the more autism-spectrum traits an individual endorsed, the less their social interaction partner liked them and the more awkward their partner felt the interaction was. Lastly, autism-spectrum traits were found to be associated with key social behaviors including smiling and eye-gaze, such that those endorsing more autism-spectrum traits smiled less and gazed downward substantially more than did those endorsing fewer traits.

Overall, while the major hypotheses of autism-spectrum disorder seem to fall short in their ability to explain the disorder, this dissertation upholds a clear link between autism spectrum traits and naturalistic social behavior and social outcomes.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.