Effects of Work Conditioning and Adjustment Period on Psychophysical Estimates in Manual Torquing Tasks

Abstract

Several issues must be addressed in experiments using psychophysical estimations, including the potential effects of work conditioning, the necessary adjustment period, and the validity of experimental results. To address these, two experiments were conducted that simulated different manual torquing tasks. In the first experiment, 16 participants provided their maximum acceptable repetition rate (MARR) in a 2-hour adjustment period, and repeated this for five consecutive days. No significant differences were found across days (i.e. no work conditioning effect). Further analysis indicated that results after 12 minutes were comparable to those at 2 hours. In the second experiment, another set of 16 participants provided estimates of 2-hour MARRs in a 12-minute adjustment period for two task conditions. On subsequent days they worked for 2 hours at their self selected MARRs. Participants were able to perform the tasks at their MARR with low to moderate average ratings of perceived discomfort on these latter days, supporting the use of a short (12-minute) adjustment period.