Adolescents are delayed at inferring complex social intentions in others, but not basic (false) beliefs: An eye-movement investigation.

Most developmental research on Theory of Mind (ToM)-our ability to infer the beliefs, intentions, and desires of others-has focused on the preschool years. This is unsurprising as it was previously thought that ToM skills are developed between the ages of 2 and 7 years. Over the last couple of decades however, studies have provided evidence for significant structural and functional changes in the brain areas involved in ToM (the "social brain") not only during childhood but also during adolescence. Importantly, some of these findings suggest that the use of ToM shows a prolonged development through middle childhood and adolescence. Although evidence from previous studies suggests a protracted development of ToM, the factors that constrain performance during middle childhood and adolescence are only just beginning to be explored. In this article, we report two visual-world eye-tracking studies that focus on the timecourse of predictive inferences. We establish that when the complexity of ToM inferences are at a level which is comparable with standard change-of-location false-belief tasks, then adolescents and adults generate predictions for other agents' behaviour in the same timecourse. However, when inferences are socially more complex, requiring inferences about higher order mental states, adolescents generate predictive gaze bias at a marked delay relative to adults. Importantly, our results demonstrate that these developmental differences go beyond differences in executive functions (inhibitory control or working memory) and point to distinct expectations between groups and greater uncertainty when predicting actions based on conflicting desires.