Beta EEG as a Correlate of Belief-Reasoning in Preschoolers

Abstract

Reasoning about beliefs is difficult, especially when others hold beliefs that conflict with one’s own. A milestone in Theory of Mind development is understanding false beliefs: the realization that others may hold representations of the world that differ from one’s own perspective (Wellman & Cross, 2001). The False Belief (FB) task has traditionally assessed this understanding by requiring children to judge a protagonist’s outdated belief about an object’s location (Wimmer & Perner, 1983). While behavioural improvements in FB performance are well-documented across preschool years, the neurocognitive mechanisms supporting successful belief-reasoning remain unclear.

This dissertation investigates the role of beta (13–30 Hz) EEG activity in children’s belief-reasoning through its association with cognitive maintenance and updating (Engel & Fries, 2010; Kilavik et al., 2013). Study 1 examined beta in preschoolers (ages 3–6, n = 39) as they completed a FB task. We focused on comparing children who passed versus failed the FB task to identify distinct neural processes underlying success and failure in belief-reasoning. During the location-change event, when belief representations are formed within the task, failers exhibited beta suppression over the posterior parietal cortex, consistent with belief updating. In contrast, passers showed evidence of beta enhancement, suggesting cognitive maintenance. These results imply that failers misrepresent the protagonist’s belief as aligned with reality.

Study 2 replicated these findings in a new sample (n = 35), where beta suppression again characterized failers and enhancement characterized passers. This study also introduced an Ignorant FB task, where children lack knowledge of the object’s new location. This condition revealed no group differences in beta; however, failers showed greater beta enhancement over the right temporo-parietal region compared to the Standard FB. This suggests they distinguished between knowledge conditions neurally, even without improved behavioural performance.

Together, these studies reveal that beta oscillatory dynamics can distinguish cognitive processes of maintenance and updating during belief-reasoning. Based on distinct beta patterns between groups, our findings suggest that failures in FB reasoning may reflect conceptual limitations in belief representation. These results contribute to theoretical accounts of ToM development, highlighting the interplay of behavioural and neural changes in belief-reasoning across the preschool years.