Overview
- A peer-reviewed paper by UCLA and Johns Hopkins authors published in PNAS reports that the usual advantage of a dominant hand reflects years of practice rather than a fixed brain asymmetry.
- To separate practice from innate control, researchers had volunteers write letters and numbers with their hands and with a pen strapped to the elbow, an effector participants had not practiced.
- Initial tests showed the expected dominant-hand edge for normal handwriting but no performance difference between dominant and nondominant elbows when using the untrained effector.
- A brief training experiment found that a few hours of practice improved elbow-writing quality substantially and symmetrically for both sides, supporting the view that dominance emerges from learning.
- Authors note limits including small sample sizes and mostly right-handed participants and say follow-up studies with left-handed people and other movements are needed because the findings could affect motor-learning and rehabilitation approaches.