Utilizing the Variability of Practice in Physical Execution, Action Observation, and Motor Imagery: Similar or Dissimilar Mechanisms?

The simulation theory argues that physical execution, action observation, and imagery share similar underlying mechanisms. Accordingly, applying a high-level psychological variable (variability of practice) should have a similar effect on all three modes. To test this theory, a total of 90 right-handed students participated in this study and were randomly divided into variable versus constant groups in three practice conditions, including physical, observational, and imagery. After a pretest (10 random trials of the putting task), the participants completed 50 practice trials. The groups performed/observed/imagined the task in the variable (different distances to different goals) or constant (fixed distance and goal) practice conditions. Also, there was an extra variable group in the physical and observational conditions, deprived of watching the feedback from the action. The participants completed a retention test 24 hr after the training. The effect of practice variability was observed in physical and observational conditions, but was not seen in the imagery condition. The no-feedback groups did not perform significantly differently from the imagery groups. The reason could be the lack of actual visual feedback during imagery.