The Effects of Personality Type and Stress on Muscle Activity during Simulated Work Tasks

Abstract

The research presented here explores the relationships between individual (e.g., personality type) and environment (e.g., time stress) psychosocial factors and muscle activity. Twenty-five subjects participated in this laboratory study. Personality type was assessed using the Jenkins Activity Survey. Participants (12 Type A and 13 Type B) performed a pipetting task under verbally imposed “no time stress” and “time stress” conditions. Independent variables included personality type, gender, condition order, and stress condition. Dependent measures included normalized integrated electromyography (NIEMG) from ten muscles. The effect of personality type on muscle activity was completely moderated by gender. Type A female dominant flexor activity was 57% of the Type B activity. Type A male dominant flexor activity was 188% of the Type B activity. Time stress increased muscle activity by 9 to 23% in six of the muscles sampled. However, the dominant flexor and extensor activities only increased (by 25 to 29%) for females. This study demonstrates the feasibility and importance of including individual and environment psychosocial factors in biomechanical evaluations.