Influence of expectation of task duration on efficiency of muscular activity.

Tested the hypothesis that intensity and organization of muscular activity is a function of s's expectation of a task's duration. The electrical activities of the following muscles were measured while 10 male undergraduates and instructors were holding a 19-lb weight under expectation for short and long tasks: biceps brachii, brachioradials, brachialis, and flexor carpi ulnaris. For the intervals measured, there was less electrical activity in all muscles during the long task. The less appropriate muscle showed the largest relative decrease. Results are interpreted as evidence of superior organization of activity under expectation of a task of long duration of work over expectation of a short duration of work. (PsycINFO Database Record (c) 2010 APA, all rights reserved)