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Right-handers' reaching in contralateral hemispace: a kinematic observation
Wondae Kim1, Carl Gabbard, John J Buchanan
1Texas A&M University, College Station, TX 77843-4243, USA.
Journal of Motor Behavior
|December 7, 2007
Summary
Right-handers use their non-dominant left arm for reaching tasks in left hemispace. This study found faster left-arm reaches and a shift to elbow-driven movements as objects move farther from the body midline.
Area of Science:
- Human kinematics
- Motor control
- Neuroscience
Background:
- Previous research indicates right-handers switch to their left arm for reaching in left hemispace.
- Understanding limb selection and movement kinematics is crucial for motor control studies.
Purpose of the Study:
- To investigate the kinematics of reaching movements in right-handers within left hemispace.
- To explore how object position influences limb selection and movement patterns.
Main Methods:
- Examined 13 strongly lateralized right-handed participants performing reaching tasks.
- Recorded kinematic data for reaches to objects at varying horizontal distances from body midline (0-40 degrees).
Main Results:
- Faster reaches were executed with the left arm for objects 20-40 degrees from midline.
- Hand acceleration time remained constant regardless of object position.
- Increased trajectory curvature and reduced upper-arm contribution were observed as object distance increased.
Conclusions:
- The findings suggest a shift from shoulder-driven to elbow-driven reaches as objects move farther leftward.
- This kinematic shift may explain the preference for non-dominant left arm use in left hemispace reaching.
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