Practice Effects on Reaction Latency for Simple and Complex Movements

Henry's “Memory Drum” theory of neuromotor reaction was applied to the learning of simple and complex movements having such short duration that feedback in its classical monitoring aspect was excluded. The theory implied that the amount of program simplification and reorganization in the learning of a simple movement is small and occurs early in the practice curve, while that for a more complex movement is larger and requires more practice to reach the limits of simplification. Subjects were college women divided into simple movement and complex movement groups of 51 each. The simple movement involved a forward movement of the arm while the complex movement required subjects to change the direction of the arm movement twice. Each subject had 50 trials on her task. Since according to theory the organization of the neuromotor program takes place before the movement starts, reaction times were used to indicate time for program organization. Movement time data was also collected. The complex movement group showed a greater shortening of reaction time than the simple movement group. The complex movement group continued to show improvement in reaction time throughout the experiment while the performance curve for the simple movement group leveled off during the first 20 trials. The data supported the implications of the theory.