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Speed-accuracy trade-off in voluntary postural movements.
Marcos Duarte1, Sandra M S F Freitas
1Laboratory of Biophysics, Escola de Educacao Fisica e Esporte, Universidade de Sao Paulo, Brazil.
Motor Control
|July 5, 2005
Summary
Fast voluntary whole-body movements during standing show that movement time depends on target distance and width. Postural control variability, like sway, significantly impacts movement accuracy.
Area of Science:
- Biomechanics
- Human Motor Control
- Postural Stability
Background:
- Fast voluntary movements are crucial for daily activities.
- Understanding the factors influencing speed and accuracy in whole-body movements is essential.
- Postural control during standing involves complex sensorimotor integration.
Purpose of the Study:
- To investigate the speed and accuracy of fast voluntary whole-body movements during standing.
- To examine the relationship between movement parameters and Fitts' law in a postural context.
- To identify the role of inherent variability in the postural control system on movement performance.
Main Methods:
- Adult participants stood on a force plate.
- Rhythmic postural movements were performed with visual feedback of the center of pressure.
- Movement time, target distance, and target width were analyzed.
Main Results:
- Movement time increased with the target distance to width ratio, consistent with Fitts' law.
- A single linear relationship was found between effective target width and mean movement speed, independent of target distance.
- Inherent variability in the postural control system, specifically sway, was identified as a key factor affecting accuracy.
Conclusions:
- Fast voluntary postural movements are influenced by the trade-off between speed and accuracy.
- The variability inherent in the postural control system significantly deteriorates the accuracy of these movements.
- Effective target width serves as a robust predictor of movement speed in postural tasks, accounting for system variability.