Shifts in attention demands and motor program utilization during motor learning

The relationship between changes in the level of motor program utilization and attention demand during the learning of a motor task was examined. The primary task involved an 86-cm horizontal arm movement which subjects attempted to complete coincident with the end of a 360 degrees sweep of a clock hand. A secondary task performed with the opposite limb required a rapid button press to an auditory probe stimulus presented at various temporal locations within each trial. Control subjects performed either the primary task or the secondary task alone, while experimental subjects performed both tasks in combination. Schmidt's (1972) index of preprogramming was used to measure the level of motor program utilization, while probe reaction time reflected the attention demand of the primary task. There was a stable level of motor programming over four consecutive days of practice (100 trials a day), but a general decrease in attention demand. Implications for an expansion of the concept of the motor program were discussed.