Growing out of your own mind: Reexamining the development of the self-other difference in the unexpected contents...

The unexpected contents task is a well-established measure for studying young children's developing theory of mind. The task measures whether children understand that others have a false belief about a deceptive container and whether children can track the representational change in their own beliefs about the container's contents. Performance on both questions improves between the ages of 3 and 4. A previous meta-analysis (Wellman, Cross, & Watson, 2001) found little evidence for a difference in children's responses on these questions, but did not investigate the weak effect size that was reported for the interaction between age and question type. The two meta-analyses reported here update the literature review, and find a more robust interaction between question type and age. Three-year-olds showed better performance on questions about their own representational change than others' false belief, while older children showed the reverse pattern. A mega-analysis of a sample of over 1200 children between the ages of 36-60 months then showed the same result. This response pattern requires novel theoretical interpretations, which include reframing the development of children's understanding of false belief.