The effects of practice trials and prior learning on motor memory.

The effects of prior positions (PL), practice reinforcements of the criterion distance (CT), and retention intervals on proactive interference (PI) in a 20-cm. linear positioning task were examined. Independent treatment groups had either 0, 3, or 5 PL, with 1, 3, or 10 CT, and a 5-, 15-, or 50-sec. retention interval. Only absolute error scores at recall indicated PI. This forgetting occurred only under the highly restricted conditions of 5 PL and 1 CT after 15-and 50-sec. retention intervals. Since 0 PL groups showed no differences in recall over levels of retention intervals, PI alone apparently caused the forgetting.