2 experiments were conducted on short-term memory for simple linear, graded motor responses, with length of retention interval and number of practice repetitions or reinforcements as basic variables. The spread of retention intervals was from 5 to 120 sec. for both experiments, and number of reinforcements as 1, 3, and 6 in Experiment I and 1, 6, and IS in Experiment II. Absolute error was the primary performance measure. Both experiments found error to be an increasing function of retention interval. Number of reinforcements was a significant variable only for the wider range of values in Experiment II, with error being a decreasing function of the variable. Results were considered parallel to those of corresponding studies on short-term memory for verbal responses. Interpretation was in terms of a rapidly decaying memory trace that becomes increasingly stable with reinforcement.