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Pointing errors reflect biases in the perception of the initial hand position
P Vindras1, M Desmurget, C Prablanc
1Faculté de Psychologie et des Sciences de l'Education, Université de Genève, 1227 Carouge, Switzerland.
Journal of Neurophysiology
|June 26, 1998
Summary
Pointing errors in visuomotor tasks may stem from biased kinesthetic sense of hand position. These systematic errors, influenced by starting location, are linked to perception, suggesting movements are planned directionally.
Area of Science:
- Neuroscience
- Motor Control
- Human Perception
Background:
- Visuomotor performance relies on accurate sensory feedback and motor planning.
- Understanding the sources of error in aimed movements is crucial for motor control research.
Purpose of the Study:
- To investigate if pointing movement errors are caused by biased estimations of the hand's starting position.
- To explore the relationship between kinesthetic perception of hand location and motor execution errors.
Main Methods:
- Three tasks were administered to 10 adult subjects involving manual pointing with varying visual feedback.
- Subjects performed pointing tasks at targets from different starting positions without visual feedback.
- A joystick task assessed perceptual estimation of the unseen hand's location.
Main Results:
- Nine subjects showed systematic pointing errors, averaging 49% of total variability, dependent on starting position.
- These motor errors significantly decreased when visual feedback of the hand was allowed before movement.
- Perceptual errors in estimating hand position were highly correlated with motor errors in the no-feedback condition.
Conclusions:
- Kinesthetic estimation of hand position can be consistently biased, with underlying mechanisms active during motor planning.
- Pointing errors significantly reflect inaccurate initial hand position estimation.
- Aimed hand movements appear to be planned vectorially (distance and direction) rather than by absolute spatial coordinates.