Experimental observation of the proportional effect hypothesis of the kinematic theory : preliminary report

For more than ten years, the Kinematic Theory has been exploited successfully in applications dealing with handwriting processing. The theory uses Delta-Lognormal profiles to model the behaviors of the motor control and the neuromuscular system involved in the production of rapid movements. Its main underlying assumption is that the cumulative time delays of the propagated impulse responses, recorded along different points on a neuromuscular system are linked by proportional relationships. The study reported in this paper aims at using the physiological knowledge of the upper arm to deeply investigate this assumption. First, the concept of a subsystem is clarified and justified. Then, to observe the proportionality hypothesis, surface electromyographic signals (SEMG) recorded from the upper limb, during the execution of rapid handwriting movements, are analyzed. The results reveal proportional regressions, with strong correlation, between the cumulative time delays of the muscle activities, calculated from SEMG envelopes. This finding highlights the relationships that exist between the macro-delays observed on the SEMG bursts and constitutes an observation proof of the proportionality hypothesis. These developments add further support to the usefulness of the Kinematic Theory as a tool for the study and understanding of human movement.

Mots clés

Kinematic Theory, rapid hand movements, proportional effect, EMG, Delta-Lognormal model, Weber’s law.