The effect of interpolated motor activities in short-term motor memory.

This experiment examined the effect of an interpolated motor response on short-term retention of a blind positioning movement. The interpolated response was varied in degree of similarity to the response length (± 25, ± 50, and ± 100 mm.), in number of repetitions (0, 1, or 5), and in temporal position (immediate or delayed), with a retention interval of 25 sec. Absolute error was not affected but a systematic change in response bias due to interpolated motor activity was found. When an interpolated response was longer than the response length, the tendency to undershoot decreased. The defay of the interpolated response was relatively more important than the number of repetitions in producing a positive shift in response bias. These results are interpreted as evidence for a form of interference in short-term motor memory.