Performance reduction in finger amputees when reaching and operating common control devices: a pilot experimental investigation using a simulated finger disability.

This paper reports results of an experimental laboratory investigation to determine if finger amputations (most pervasive upper extremity injury in the United States) result in significant work performance deterioration in tasks requiring operation of common control devices found in industrial settings. Ten male student volunteers from the University of Cincinnati participated in this study. The finger disability simulated was of an extreme nature, and was defined as the loss of four fingers in the preferred hand and the thumb in the nonpreferred hand. While being seated, participants activated 5 types of industrial control devices (a rotary dial, a push button, a toggle switch, a castor wheel, and a rocker switch). The controls were assembled on a device attached to a cylindrical pole, such that the control assembly could move up and down the cylindrical pole. The vertical height of control location (15, 20, and 30 in. from the seat reference point) and angle of control location in vertical plane (0 degree, 45 degrees, 90 degrees, and 135 degrees) were varied in the experiment. Participants also had their torso restrained or unrestrained while reaching and activating controls, in addition to the presence or absence of the simulated disability in each participant. Functional reaches and arm reaches from the wall were measured for participants in the sample to determine the distances at which to place the control pole assembly. If a participant was able to reach the control, the time taken to activate and operate the control was recorded. Overall results indicate that participants took significantly longer (p < 0.05) to activate controls in the presence of the simulated disability. Physical restraint did not significantly alter performance provided the participant was able to reach the control. The type of control and the height of location of the control also significantly affected work performance.