True- and false-belief reasoning in children and adults: an event-related potential study of theory of mind.

The understanding that another person's belief can differ from reality and that behaviour is guided by beliefs and not by reality reflects an important cornerstone in the development of a Theory of Mind. The present event-related potential (ERP) study had two aims: first, to reveal ERPs that distinguish between false- and true-belief reasoning and second, to investigate the neural changes in the development of false- and true-belief reasoning from childhood to adulthood. True- and false-belief cartoon stories were presented to adults and 6-8-year-old children. Results revealed two waveforms that differentiated between the two conditions: a late positive complex (LPC) associated with the reorientation from external stimuli to internal mental representations and a late anterior slow wave (LSW) associated with stimulus-independent processing of internal mental representations, a process that might be centrally involved in the decoupling mechanism. Additionally, we found developmental effects at an ERP level. Children showed a more posterior localization of the LPC and a broader frontal distribution of the LSW. The results may reflect developmental progress in conceptualizing the mental domain and support the idea that the cortical mentalizing network continues to develop even after children are able to master false beliefs.