Visual sense has a great role for the hand movement. Particularly, infants control their gaze shift and fixations proactively to use their visual sense for guiding movements in goal-directed actions. However, few studies have examined precise spatial and temporal relationships between infants' gaze fixations and actions. This study investigated the gaze control and dexterous manipulation of goal-directed action in infants. The participants consisted of two groups : the younger group of 9 to 12 month-olds and the older group of 17 to 19 month-olds. While infants' eye gaze was measured during the motion observation task in Experiment 1, the infant's hand movement was video recorded during the performance of the block task in Experiment 2. Experiment 1 examined whether the older group would gaze at the GOAL area proactively, while they watched the PATH area for less time than the younger group. Experiment 2 investigated whether the older group would move their hand with a longer deceleration phase in the motion unit and if their hand trajectory would be more uniform than in the younger group.
The results indicated that the younger group attended more to the moving object (i.e., the PATH area) while the older group shifted their eye-gaze earlier to the goal area. On the other hand, in Experiment 2, the younger group hardly accomplished the block task. The results of Experiment 2, however, revealed significant differences between groups in a series of grasping behaviors as well as some significant relationships between speed or stability and quality of hand movement. Finally, the results revealed the relationship between eye-gaze and hand movement. The fixation % in the PATH area had a significant positive correlation with the speed index of the hand movement. This suggests that the dexterous actors in the manipulation task could control their gaze more effectively. The present study successfully quantified eye movements and dexterous hand movement in infants thereby showing a significant relationship between them and their development.

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