Influence of extended practice on programming time, movement time, and transfer in simple target-striking responses

Two experiments describe the effects of extended practice on the development of motor control programs for simple target-striking responses. In Experiment 1,400 right-hand trials of simple one-target and two-target striking tasks were performed. In Experiment 2,600 practice trials were given. Overall reaction time (RT) was faster for the one-target condition in both experiments, supporting a response complexity effect. Movement time (MT) for both conditions improved linearly with practice, suggesting that development of the motor control programs was still occurring. Subjects then transferred to a three-target condition for 50 trials, performing the transfer task with the right hand in Experiment 1, and with right and left hands in Experiment 2. Transfer to the three-target conditions produced execution errors in the form of failure to contact the second target and repetitive tapping on the third target. These results suggest that extensive practice may serve to firmly entrench a response sequence, making it difficult to implement a similar, but unique, motor control program. An interpretation in terms of automaticity and enhanced priming of behavioral and neural pathways is offered to account for these results.