Ten- and twelve-month-olds' visual anticipation of orientation and size during grasping

The anticipation of two object dimensions during grasping was investigated in 10- and 12-month-olds. We presented objects varying in both orientation and size and analyzed infants’ anticipatory hand configurations. We found in Experiment 1 that nearly all of the 12-month-olds (94%), but less than half of the 10-month-olds (40%), anticipated both dimensions before touching the object. Experiment 2 ruled out the possibility that this behavior resulted from the infants’ inability to anticipate the size of the stimuli. Thus, integrating two object dimensions during reaching seems to be difficult for 10-month-olds. In addition, we found a sequential adjustment when two dimensions were considered: Infants first adjusted the orientation and then the size. The implications of our findings concerning the planning and execution of grasping movements are discussed.