Perceptual-motor constraints on decision making: the case of the manual search behavior for hidden objects in toddlers.

In the C-not-B task, 2.5-year-old children tend to look for an object in a location to which the hiding agent moved his hand (C) after moving an object from A to B. In three experiments, the authors investigated the nature of the constraints underlying toddlers' performance in this task. In Experiment 1, 2.5-year-olds were tested in a new version of the C-not-B task to investigate whether reaching with a detour leads to inhibition of direct visuomotor activation. The findings show that toddlers succeed more in the C-not-B task when a transparent barrier obstructs the path of the reaching movement. The results of Experiment 2 indicate that the successful performance of the children with a barrier cannot merely be the consequence of the longer duration of arm movements. In Experiment 3, pointing responses generated more toddlers' success in the C-not-B task than did reaching responses. These experiments suggest that decision-making processes and judgments in toddlers are affected by constraints intrinsic to the perceptual-motor system.