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Visual feedback and anticipatory hand orientation during infants' reaching
1Psychology Department, University of Western Ontario, London, Canada.
Insights
Infants improve their reaching skills with age, developing better hand orientation and visual feedback use. By 9 months, babies efficiently grasp objects, unlike younger infants who struggle with dynamic tasks.
Area of Science:
- Developmental Psychology
- Motor Control
- Infant Perception
Background:
- Infant motor development involves complex coordination of perception and action.
- Understanding how infants adapt reaching movements is crucial for developmental studies.
Purpose of the Study:
- To investigate age-related changes in infant reaching and hand orientation adjustments.
- To examine infants' ability to use visual feedback for corrective movements.
Main Methods:
- Videorecorded reaching tasks with stationary and moving stimuli for 5, 7, and 9-month-old infants.
- Monitoring of visual fixation and hand orientation during reaching.
- Analysis of reaching efficiency and object contact.
Main Results:
- 5-month-olds showed poor hand orientation adjustment compared to 9-month-olds.
- Infants' ability to adjust hand orientation improved with age, especially when the object's orientation changed.
- 9-month-olds demonstrated superior efficiency in object contact and grasp incidence.
Conclusions:
- Infant reaching skills mature significantly between 5 and 9 months of age.
- Visual feedback plays a critical role in refining hand orientation during reaching.
- Developmental improvements enable infants to adapt to dynamic changes in their environment.
Abstract:
Infants 5, 7, and 9 mo. of age were videorecorded while reaching for a dowel that either was stationary or changed orientation after initiation of a reach. Visual fixation and hand orientation were monitored throughout each reach, as was the efficiency with which infants contacted the stimulus. In reaching for the stationary stimulus, the 5-mo.-olds showed significantly poorer hand orientation adjustment throughout their reach than 9-mo.-olds. The 7-mo.-olds began a reach with the hand poorly oriented as did 5-mo.-olds, but just before object contact their performance matched that of the 9-mo.-olds. On change-orientation trials, the 5-mo.-olds' reaching was disrupted. They missed, stopped, or withdrew their reach on over half of these trials, and hand orientation on contact was significantly worse than on no-change trials. By contrast, older infants were more skilled in using visual feedback to make corrective adjustments in hand orientation during execution of the reach to secure a smooth contact with the stimulus. These infants showed no difference in hand orientation on contact for change in comparison to no-change trials. The 9-mo.-olds' performance surpassed that of the 7-mo.-olds only in the efficiency with which they contacted the stimulus and the incidence of grasps on first contact.