The Role of Variability in Practice Structure when Learning to Use an Upper-Extremity Prosthesis

This study contrasted two different practice schedules for learning to use a prosthetic simulator that mimicked an upper-extremity prosthesis with a voluntary-close terminal device. The purpose was to determine an efficient practice schedule for learning to perform prehension skills that could be employed by people learning to use an actual prosthesis after amputation. Forty-eight participants were randomly distributed into two groups for skill acquisition training: those who practiced three different prehension tasks with the simulator in a random practice order or those who practiced the three tasks with the simulator under a blocked practice order. During acquisition, the groups practiced the three tasks on two consecutive days. On the third day, two different tests of learning were administered: a retention test on the tasks practiced in acquisition and an intertask transfer test on three tasks similar to those practiced in acquisition. Both the random and blocked groups showed significant improvements in initiation time and movement time to perform each task across the 2 days of acquisition. Thus, structured practice, regardless of degree of "randomness" inherent in the schedule, promoted functional use of the prosthesis. Both practice schedules were equally effective for promoting skill retention; however, in intertask transfer, the random acquisition group demonstrated significantly greater proficiency in performing the new tasks than the blocked acquisition group. Persons learning to use an upper-extremity prosthesis may be better able to transfer skill to new prehension tasks by practicing under random practice conditions.