Manual reach tracking reveals distinct inhibitory processes in children’s and adults’ inferences about belief

Numerous studies suggest that there are relations between children’s developing inhibitory control and their ability to make inferences about others’ false beliefs. The present study examined how 4- to 6-year-olds (46 girls, 27 boys, 73 % White, 7 % Black, 16 % Asian, 4 % Hispanic) and adults (15 female, 10 male) in the Northeastern United States inferred others’ belief states while tracking their reaching movements in 3D space over time. This approach allowed us to separate the inhibitory resources needed for detecting conflict in decision-making options (measured through latency to reach) from those needed for resolving the conflict to make a response (measured through the maximal deviance in the curvature of their reach). We found no differences in the inhibitory process involved in the detection of conflict when children or adults were asked to make inferences about true or false beliefs. We did find a significant interaction regarding the inhibitory process involved in resolving conflict: As children’s understanding of theory of mind improved, they were more adult-like, requiring fewer conflict resolution resources to respond correctly to false belief trials. Responding correctly to a false belief inference involves a similar monitoring process as responding correctly to a true belief inference, but a different conflict resolution process, which was related to children’s developing theory of mind.