Functional asymmetries in the quality of handwriting movements: A kinematic analysis

Writing hand preference is a prominent functional asymmetry, but biomechani cal factors may also contribute to any kinematic differences in the quality of handwriting movements performed by either hand. Eighteen dextral partic ipants used a noninking pen with their right or left hand to write cursive letter is, inverted Is, and their mirror images (to control for biomechanic al differences) on a graphics tablet. Kinematic analysis of the scaling, co nsistency, efficiency, and shape of writing stroke trajectories revealed fu nctional asymmetries between hands. The right hand was faster and produced more efficient strokes, which were of more consistent length, duration, and peak velocity. Differences between hands do not simply reflect biomechanic al factors; therefore, the documentation of any functional asymmetries may allow their subsequent use as markers of underlying pathology in conditions such as schizophrenia.