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Development of visually guided hand orientation in reaching
Insights
Infants develop hand-eye coordination by learning to adjust their grasp to object orientation. This study tracked infant visual-manual skill development from 18 to 34 weeks, showing rapid improvement in grasping accuracy.
Area of Science:
- Developmental psychology
- Motor control
- Infant visual-manual integration
Background:
- Understanding how infants develop visually guided reaching is crucial for developmental neuroscience.
- Early motor skills, including grasping, are foundational for cognitive development and interaction with the environment.
Purpose of the Study:
- To investigate the developmental trajectory of visually guided hand orientation adjustments in infants.
- To determine when and how infants learn to match their hand shape to object orientation during reaching.
Main Methods:
- Longitudinal study of 15 infants from 18 to 34 weeks of age.
- Presentation of horizontal and vertical rods at 4-week intervals.
- High-speed kinematic analysis (60-msec intervals) of hand orientation during the final 540 msec of reaching.
Main Results:
- Infants showed initial, albeit incomplete, hand orientation adjustments to object orientation even at 18 weeks.
- A rapid and significant improvement in this visually guided skill was observed throughout the study period.
- The findings suggest early visual information about object orientation is available to the motor system.
Conclusions:
- Infant reaching demonstrates a developmental refinement of visual-motor calibration.
- The manual system gains access to object orientation information early, but requires maturation for precise execution.
- This study highlights the dynamic interplay between visual perception and motor control in early development.
Abstract:
The development of an ability to use vision in adjusting the hand and the fingers to the orientation of an object to be grasped was studied in a group of 15 infants. They were 18 weeks at the first session and were seen at 4-week intervals until 34 weeks old. At each session they were presented with horizontal and vertical rods. The orientation of the hand of the infant when reaching for these rods was measured at each 60-msec interval during the last 540 msec of the approach. It was found that even at the youngest age there were signs of adjustment of the hand to the orientation of the object. However, at that age the adjustments were rather incomplete. During the months that followed there was a rapid improvement in the skill studied. The findings were in accordance with the idea that information about object orientation is accessible to the manual system when infants start reaching for objects but that the system has yet to be tuned and calibrated before functioning adequately.