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Is visually guided reaching in early infancy a myth?
R K Clifton1, D W Muir, D H Ashmead
1Department of Psychology, University of Massachusetts, Amherst 01003.
Insights
Infants do not need to see their hands to reach and grasp objects. Proprioceptive cues, not visual guidance, enable early infant reaching and object contact in both light and dark conditions.
Area of Science:
- Developmental Psychology
- Infant Motor Development
- Sensory Integration
Background:
- Understanding the sensory mechanisms guiding early infant motor skills is crucial for developmental research.
- The role of visual feedback versus proprioception in infant reaching and grasping remains an area of investigation.
Purpose of the Study:
- To determine if infants require visual sight of their hands for initial object interaction.
- To compare the development of reaching, contacting, and grasping in light versus dark conditions.
Main Methods:
- Tested 7 infants between 6 and 25 weeks of age.
- Presented objects in both light and complete darkness (glowing/sounding objects).
- Recorded age of first object contact and grasp in both conditions.
Main Results:
- Infants achieved first object contact at comparable ages in light (12.3 weeks) and dark (11.9 weeks).
- First grasp occurred at similar ages in light (16.0 weeks) and dark (14.7 weeks), a nonsignificant difference.
- Consistent object touching and grasping observed in both conditions once initiated.
Conclusions:
- Proprioceptive cues, not visual limb guidance, are critical for early infant reaching and object contact.
- Visual guidance of the hand is not essential for initiating or sustaining object contact during early development.
Abstract:
The issue examined was whether infants require sight of their hand when first beginning to reach for, contact, and grasp objects. 7 infants were repeatedly tested between 6 and 25 weeks of age. Each session consisted of 8 trials of objects presented in the light and 8 trials of glowing or sounding objects in complete darkness. Infants first contacted the object in both conditions at comparable ages (mean age for light, 12.3 weeks, and for dark, 11.9 weeks). Infants first grasped the object in the light at 16.0 weeks and in the dark at 14.7 weeks, a nonsignificant difference. Once contact was observed, infants continued to touch and grasp the objects in both light and dark throughout all sessions. Because infants could not see their hand or arm in the dark, their early success in contacting the glowing and sounding objects indicates that proprioceptive cues, not sight of the limb, guided their early reaching. Reaching in the light developed in parallel with reaching in the dark, suggesting that visual guidance of the hand is not necessary to achieve object contact either at the onset of successful reaching or in the succeeding weeks.