Cognitive factors and family structure associated with theory of mind development in young children

Factors associated with individual variation in false belief understanding were examined. Sixty-eight 3- to 5-year-olds were tested on 4 standard false belief tasks. General language ability and verbal memory were found to be significant predictors of false belief understanding after the effects of age were partialled out, but nonverbal memory was not. There was evidence for a threshold effect in that children did not pass false belief tasks before they reached a certain level of linguistic ability. False belief scores were higher in children from larger families, after the effect of age and language had been partialled out. Family size was more strongly associated with false belief understanding in children who were less competent linguistically, suggesting that the presence of siblings can compensate for slower language development in developing false belief understanding.