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Updated: May 16, 2026
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Postural Organization of Gait Initiation for Biomechanical Analysis Using Force Platform Recordings
Published on: July 26, 2022
Fitts' Law in early postural adjustments.
M Bertucco1, P Cesari, M L Latash
1Department of Biomedical Engineering, University of Southern California, 1042 Downey Way, DRB 140, Los Angeles, CA 90089, USA. bertucco@usc.edu
Neuroscience
|December 6, 2012
Summary
Fitts' Law in pointing movements reflects motor planning, not online corrections. Movement time and difficulty relations change with movement distance due to body segment contributions and Coriolis forces.
Area of Science:
- Neuroscience
- Biomechanics
- Human Motor Control
Background:
- Fitts' Law describes the relationship between movement time and the index of difficulty (ID) in rapid pointing tasks.
- The underlying neural and biomechanical processes governing Fitts' Law are debated, specifically whether it reflects motor planning or online movement corrections.
Purpose of the Study:
- To investigate whether Fitts' Law is primarily a manifestation of motor planning processes.
- To examine how variations in movement distance, and associated biomechanical factors like Coriolis forces, influence the Fitts' Law relationship.
Main Methods:
- Healthy subjects performed rapid, accurate hand movements towards targets of varying size and distance while standing on a force platform.
- Movement kinematics, forces, and moments were recorded to analyze early postural adjustments and movement execution.
- Analysis focused on the relationship between movement time and index of difficulty (ID) under different movement distances.
Main Results:
- Movement time consistently scaled with the index of difficulty (ID) for both short and long distance movements.
- A single regression model did not fit both conditions; longer movements exhibited a greater intercept, indicating approximately 140 ms longer movement times.
- Pre-movement postural adjustments scaled with ID, supporting their role in motor planning.
Conclusions:
- The findings strongly support the hypothesis that Fitts' Law emerges from motor planning processes, not online movement corrections.
- Changes in movement distance can alter the Fitts' Law relationship, particularly when involving different body segments and external forces like Coriolis forces.
