UCLA Study Finds Dominant Hand Edge Fades Without Practice in 2 Experiments
Updated
Updated · UCLA Health · Jun 30
UCLA Study Finds Dominant Hand Edge Fades Without Practice in 2 Experiments
3 articles · Updated · UCLA Health · Jun 30
Summary
PNAS published a UCLA Health study showing dominant-hand superiority largely vanished when adults used unfamiliar effectors or simple reaching tasks, undermining the idea that one brain hemisphere is inherently better at motor control.
3D motion-capture tests found dominant and nondominant arms performed about the same during normal reaching and with a 4-pound wrist weight, but the dominant arm pulled ahead when a stick strapped to the forearm mimicked tool use.
Writing tests showed the same pattern: when a pen was taped to participants' elbows, both sides wrote equally poorly at first, then improved by similar amounts with practice.
Dr. Ahmet Arac said the findings point to a lifetime of rehearsing complex, curved movements used for tools and handwriting—not a built-in neural advantage—as the source of handedness skill gaps.
The results could help stroke rehabilitation and motor-learning research by suggesting skilled movement can be rebuilt through practice rather than relying on fixed dominance in the brain.