Arm dominance is an emergent effect of practice executing complex trajectory shapes required by tools and objects

• 成果类型: Article
• 署名作者: Arac, Ahmet; Lee, Nicolas Y. H. Jeong; Krakauer, John W.
• 署名单位: University of California System; University of California Los Angeles; David Geffen School of Medicine at UCLA; University of California Los Angeles Medical Center; Johns Hopkins University; Johns Hopkins Medicine; The Santa Fe Institute
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2601569123
• 发表日期: 2026-07-07
• 页码: e2601569123
• 关键词: arm dominance; shape analysis; tool-use; trajectory control; primary motor cortex; HAND PREFERENCE; functional-organization; premotor cortex; handedness; MOVEMENT; COORDINATION; monkey; REPRESENTATIONS; ADVANTAGES

摘要

Limb dominance is a human behavioral characteristic with many cultural, practical, scientific, and clinical implications. Yet why the dominant limb performs better across a range of motor skill-requiring tasks remains unanswered. Is it because of an intrinsic hemispheric advantage or instead is it the result of life-long practice with the dominant side? We tested these alternatives using two tasks either cross sectionally or after training. The first was 3D reaching with either an inertial challenge or the need to use a stick-like tool. The second required participants to write with their dominant and nondominant elbows. We applied a geometric analysis to quantify movement-trajectory shape. We show that 1) tool-use unmasks markedly inferior control in the nondominant arm, and this is because tools impose the need to generate unfamiliarly shaped movement trajectories; and 2) there is no general dominant limb motor control advantage, only task-specific experience or practice riding on top of an initial preference. These results reframe dominance as predominantly about learned control of tool kinematics rather than baseline asymmetry in control of limb dynamics.