Some Features of the After-Contraction Phenomenon

Abstract

The well-known unintentional muscular contraction following a voluntary contraction was found to be inhibited by instructions favouring relaxation, to be increased by a difficult concurrent task and to be superimposed on small voluntary contractions of the same muscles. It was not superimposed (in either sense) on antagonist contractions. An explanation is suggested, based on the interaction of sensory adaptation and some other process known to occur and apparently related to fatigue.