Resting-state EEG alpha asymmetry predicts false belief understanding during early childhood: An exploratory longitudinal study

Theory of mind (ToM), the ability to attribute mental states to others, is fundamental to human socio-cognition. In child development, a full or explicit understanding of false beliefs (FB) and their impact on action emerges around the age of 4 years. There is evidence of functional specialization of right hemispheric activity related to FB processing in adults and children. However, it remains unclear whether this specialization is the cause or the consequence of ToM development. The present exploratory study investigates the longitudinal relationship of resting-state electroencephalogram (rsEEG) alpha asymmetry measured in infancy/toddlerhood and behavioral false belief understanding (FBU) at the age of 4 years. Employing a longitudinal design, Study 1 assessed rsEEG alpha asymmetry across frontal and parietal electrode sites (N = 43), implicit FBU at 34 months (N = 38), and explicit FBU at age 4 (N = 22). Study 2 is another independent longitudinal dataset that included rsEEG alpha asymmetry at 14 months (N = 37) and explicit FBU at age 4 (N = 32). We found that superior explicit FBU at age 4 was associated with greater right frontal activity at an earlier age, and better implicit FBU was cross-sectionally related to greater right parietal activity. Given the limited sample size, these results should be viewed as preliminary and warrant replication in future studies. Interpreted cautiously, these findings may suggest that rsEEG alpha asymmetry in frontal regions may serve as an early-appearing neural marker of children's later explicit FBU.