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Abstract

Covert motor practice methods, such as motor imagery (MI, the mental representation and rehearsal of a physical action without any overt movement), or observation (OBS) of another individual physically practising, can induce motor learning and have the capacity to facilitate intermanual transfer. These covert methods can supplement physical practice to augment learning outcomes, or even to serve as alternatives. However, knowledge gaps exist regarding the mechanisms of these covert processes and if/how the encoding processes differ as compared to physical practice. One way to better understand these processes is through the study of intermanual transfer. Across three experimental groups, participants either physically practised (PP), watched a partner practise (OBS), or imagined practising (MI) an underhand dart throw to a target on the floor. All groups were tested on the practised (dominant right) and non-practised (non-dominant left) hands in a pretest, immediate posttest, and 24hr retention test. All groups improved from pre to posttest, particularly the PP group, and covert practice groups better retained these improvements across the retention interval. Although there were not the expected Group X Hand interactions in the posttests, the correlations between amount of improvement in the practised hand compared to the non-practised hand were strongest for the covert groups in comparison to the PP group, showing a greater matching across the hands at the participant level for these groups. Calculations of transfer, in terms of relative improvement in each hand from pre to posttests, did not yield group differences (being greater than 85% for all groups). Significant offline gains were made by the OBS group as compared to the MI group, especially for the non-practised hand. Measures of movement time (MT) and imagined movement time (iMT) gave an index of the equivalence between imagined and actual movements. The practised hand showed the best ‘equivalence,’ but there were no group differences. These data indicate a general efficacy in covert motor practice methods for supporting transfer and the potential for continued learning over the retention interval. Transfer was comparably strong across all groups, particularly even the PP group, surprisingly, suggesting similarities in sensorimotor representations acquired for this task.