Testing Understanding of False Belief
Wimmer and Perner (1983) devised the 'Sally-Ann' task diagramed below to test children's understanding of false belief.  In Step 1, the child watches as Sally puts the marble in the basket.  In step 2, the child sees Sally leave the scene.  In Step 3, the child watches as Ann moves the marble from the basket, hiding it in the box.  In Step 4, Sally returns to the scene, and the child is asked where Sally will look for the marble.  In the original study, most 3- and 4-year-olds mistakenly said that sally would look in the box, suggesting that their understanding of false belief was deficient.  Later variants of this task by Gopnik and Astington (1988) and Wellman and Bartsch (1990) minimized the salience of the movement tansformation.  For example, in Wellman and Bartsch, children were only show the scence in Step 4 and were asked to guess where the marble was.  They were then told that Sally though the marble was in the alternate location and were asked to judge where Sally would search (that is, both the physical transformation of moving the marble from one place to another and the requirement that childrne would need to remember the original position were removed from the procedure).  In the Wellman and Bartsch, 3-year-olds, but not 2-year-olds, could give accurate predictions.  This series of results suggests that young children's command of false belief understanding is quite fragile.