Task difficulty and the efficiency of muscular activity

Abstract

Hypothesized that intensity and organization of muscle activity are functions of S's expectation of difficulty of a task. Task difficulty was varied for 15 20-40 yr. old instructors and undergraduates by preparing S for holding heavy and light weights, respectively. The difficult task consisted of holding a 41-lb weight following 30 sec. of holding a 19-lb weight. The easy task was holding a 6-lb weight following 30 sec. of holding the 19-lb weight. Electrical activity of the following muscles of the right (active) arm was measured: biceps brachii, brachialis, brachioradialis, flexor carpi ulnaris, and triceps. During the holding of the middle range weight, muscle activity was lower in preparation for the heavy weight than for the light weight, but there were no significant changes in the organization of muscle activity. (PsycInfo Database Record (c) 2025 APA, all rights reserved)