Abstract
We have shown that individuals with visual-motor experience exhibit interference from secondary motor tasks when making perceptual decisions. This is consistent with the motor simulation hypothesis of action prediction. Because of the interference, despite concurrent accrual of visual and motor experiences, this simulation appears to be automatic. However, it has been suggested that we can acquire separate (visual)motor and purely visual representations that allow for accuracy in the presence of motor interference. Therefore, we trained people (N=16 to date) to develop separate (visual)motor and visual representations. "Motor" practice involved learning to throw darts at 3 sections of a dartboard. "Visual" practice involved matching occluded throws with landing outcomes, on video. One group (Motor>Vis) underwent motor practice on day1 and visual on day2. The Vis>Motor group did the reverse. Prediction tasks (judging outcomes from occluded clips) were performed by both groups before and after practice each day, and some trials involved secondary motor tasks (pushing on a force gauge). Consistent with previous work, the Motor>Vis group improved prediction accuracy on day1, except when performing the secondary task. After visual practice on day2, prediction accuracy was maintained, but now there was no interference. The Vis>Motor group, after day1 visual training, showed a similar improvement in prediction accuracy, with no decrement under secondary task conditions. After motor training on day2, accuracy was maintained, without interference. These data suggest that motor simulation is not automatic, and that separately-acquired motor and visual experiences allow flexibility in adopting prediction strategies most robust to external task demands.Acknowledgments: The last author would like to acknowledge NSERC for financial support of this research