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Effort, success, and nonuse determine arm choice
Nicolas Schweighofer1, Yupeng Xiao2, Sujin Kim3
1Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California; schweigh@usc.edu.
Journal of Neurophysiology
|May 8, 2015
Summary
Humans choose which arm to use based on expected effort and task success, influenced by handedness. This research sheds light on arm nonuse after stroke.
Area of Science:
- Motor control and decision-making
- Human movement science
Background:
- Human arm choice for reaching targets is theorized to involve action value comparison.
- Motor control theories suggest minimizing motor cost (effort vs. accuracy) during movement planning.
Purpose of the Study:
- To investigate if arm choice is determined by comparing action values, including expected effort, task success, and handedness bias.
- To understand the factors influencing the selection between the right and left arm for reaching tasks.
Main Methods:
- Right-handed subjects performed reaching tasks under different target conditions.
- Effort was quantified using inverse kinematics and dynamics.
- Mixed-effects logistic regression analyzed choice determinants, including prior arm use.
Main Results:
- Both expected effort and expected task success significantly predicted arm choice.
- Previous arm use on a trial also influenced subsequent choices.
- Individual handedness bias correlated with the difference in success rates between arms, favoring the right arm.
Conclusions:
- Arm choice is a complex decision influenced by expected outcomes (effort, success) and ingrained biases like handedness.
- Findings offer insights into understanding arm nonuse patterns observed in post-stroke individuals.
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