Repeatability of Magnitude Production in Isometric, Hand-Grip Force Estimation: A Working-Memory Approach

Summary.-Magnitude production has been used in ergonomics research to quantify hand-grip and finger-pinch force exertions. The repeatability of this psychophysical method may be affected by a memory component if the subject must recall multiple, previously performed force exertions. This investigation tested the hypothesis that the number of different to-be-remembered hand.gr~p force exertions would affect the repeatabhty of force productions obtained via rn'lgn~rude production for 12 male students. Four levels of force were examined (20%, 35'%, 50%, and 65% of subject's individual maximum) at low and high memory loads (nvo versus four forces to be cemembered concurrently). Amount of force had a significant effect on the variance among a sample of five observations; however, memory load showed no effect on the variance measure. Thus, it is concluded that four forces do not pose a signZicancly greater memory load than nvo forces for perceived force in hand-grip magnitude productions.