Legible - Motor Control

Motor Control

Handwriting requires the motor coordination of multiple joints in the hand, wrist, elbow, and shoulder to form letters and to arrange them on the page. Holding the pen and guiding it across paper depends mostly upon sensory information from skin, joints and muscles of the hand and this adjusts movement to changes in the friction between pen and paper. With practice and familiarity, handwriting becomes highly automated using motor programs stored in motor memory. Compared to other complex motor skills handwriting is far less dependent on a moment-to-moment visual guidance.

Research in individuals with complete peripheral deafferentation with and without vision of their writing hand finds increase of number of pen touches, increase in number of inversions in velocity, decrease of mean stroke frequency and longer writing movement duration. The changes show that cutaneous and proprioceptive feedback play a critical role in updating the motor memories and internal models that underlie handwriting. In contrast, sight provides only a secondary role in adjusting motor commands.