Information capacity of discrete motor responses under different cognitive sets.

Abstract

Previous findings on the interrelations of speed, amplitude, and accuracy of movements support the conclusion that the human motor system has a relatively constant information capacity over rather wide limits. The 2 experiments here reported examine extensions of this conclusion by comparing movements that are initiated at S''s [subject''s] convenience vs. movements following a 2-choice reaction time, and the effects of variations in instructions and payoffs emphasizing speed vs. accuracy. It is concluded that (a) there is little or no benefit in spending additional time in preparation for the initiation of a skilled movement; only an increase in the time actually spent in executing a movement is of value in increasing accuracy, and (b) within limits the information capacity of the human motor system is relatively invariant under changing cognitive sets for speed vs. accuracy,.