Executive functioning in preschoolers: Reducing the inhibitory demands of the dimensional change card sort task

To investigate the role of inhibitory control in preschoolers ’ ability to switch sets, 3 conditions of the Dimensional Change Card Sort task ( Zelazo, Reznick, & Pinon, 1995) were tested. In Condition B (novel response options, standard stimuli) action inhibition was reduced, but the need for attentional inhibition was maintained. In Condition C (novel stimuli, standard response options) demands on both action and attentional inhibition were reduced. Performance in these was compared to that in the standard condition (A). Rule complexity was comparable across conditions. All 21 children who passed preswitch (average age 37 months) were tested on all postswitch conditions, order counterbalanced. Although reducing demands on action inhibition (Condition B) did not significantly improve performance, when demands on both ac-tion and attentional inhibition were reduced (Condition C) almost all children (95%) successfully switched sets (even children only 2 years old). Inadequate inhibition (of attention alone or both attention and action) appears sufficient to account for vir-tually all errors by preschoolers on this card sorting task. Executive functioning (EF) is a highly complex set of processes essential to the ev-eryday working of humans when controlled, rather than automatic, processing is required (Shallice, 1988). Although there is debate about what constitutes EF, these executive abilities, considered to be subserved by frontal systems, are evi-dent in tasks such as the A-not-B (Piaget, 1954), Stroop (Stroop, 1935), and Wis