Flankers facilitate 3-year-olds' performance in a card-sorting task.

Three-year-old children often act inflexibly in card-sorting tasks by continuing to sort by an old rule after being asked to switch and sort by a new rule. This inflexibility has been variously attributed to age-related constraints on higher order rule use, object redescription, and attention shifting. In 2 experiments, flankers that were congruent with the new rule significantly facilitated 3-year-olds' use of the new rule and did so without changing the requirement to use higher order rules, redescribe objects, or shift attention. The results suggest that preschoolers' inflexibility is linked, in part, to the degree of conflict that must be resolved in postswitch trials.