Finding your marbles: does preschoolers' strategic behavior predict later understanding of mind?

The aim of this longitudinal study was to assess (a) stability of individual differences in preschoolers' executive function performance, (b) the external validity of 4 new simple executive function tasks, and (c) whether individual differences in early executive function performance could be used to predict later differences in theory of mind, or vice versa. Fifty children involved in an earlier study of relations between preschoolers' theory of mind, verbal ability, and executive function (C. Hughes, 1998) were followed up and tested 1 year later, using 1st- and 2nd-order false-belief tasks, a set of 4 simple executive function tasks, and a well-established executive test of planning: the Tower of London (T. Shallice, 1982). The results of the study support recent proposals (C. Hughes, 1996; J. Russell, 1996) that young children's understanding of mind is grounded in their growing competence in strategic planning and mental flexibility.