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Unconscious updating of grasp motor program
M Gentilucci1, E Daprati, I Toni
1Istituto di Fisiologia Umana, Università di Parma, Italy.
Experimental Brain Research
|January 1, 1995
Summary
Human grasp adjusts to object size changes, even without conscious awareness, demonstrating a pragmatic understanding of size. Kinematic adjustments compensate for temporal perturbations during grasping.
Area of Science:
- Neuroscience
- Human Motor Control
- Perception
Background:
- Grasp modification is crucial for successful object interaction.
- Understanding how sensory information influences prehension is key to motor control research.
Purpose of the Study:
- To investigate how somesthetic information about object size variations affects grasp modification during prehension.
- To explore the interplay between visual and somesthetic feedback in adapting grasp kinematics.
Main Methods:
- Three experiments involving reaching and grasping objects with changing sizes.
- Subjects performed matching tests to reproduce object size.
- Manipulated visual and somesthetic information reliability and availability.
Main Results:
- Maximal grip aperture and finger aperture adapted to object size changes, even when subjects were unaware.
- Grasp time was altered by size variations, with greater effects observed for size decrease.
- Altering visual reliability or preventing vision influenced adaptation, suggesting vision's role in masking changes.
Conclusions:
- Kinematic parameters like maximal grip aperture can be modified to compensate for temporal perturbations during grasping.
- A pragmatic, non-conscious knowledge of object size is formed, influencing motor execution.
- Sensory feedback, particularly vision, plays a significant role in the conscious detection and compensation of object property changes.