Abstract
The presence of aftereffects in a visuomotor adaptation task implies that an existing internal model has been updated. Previously we reported that although observers adapted to a perturbation (30º rotation) they did not show aftereffects. In this experiment we tested 2 observer groups (n=8/gp) who were more actively engaged in watching (encouraged through imagery and estimation), with one group additionally performing 50 trials interspersed during observation. Hand movement estimation trials (t=25/200) allowed us to assess explicit knowledge and hypotheses about the mode of learning. These estimations were compared to an additional Actor group (n=10). The pure Observation group improved their ability to estimate hand movement of the video model during adaptation. Although the Actor and Mixed groups adapted their movement, they did not improve in estimation. As before, the pure Observation group did not show aftereffects, whereas the Actor and Mixed groups did (p<.05). Surprisingly, aftereffects in the Mixed group (75% observation) were larger than the Actors. We suggest that observation encourages a more explicit mode of learning, enabling performance benefits without corresponding changes to an internal model of the mapping between motor output and sensory input. However, some physical practice interspersed with observation can change the manner with which learning is achieved, encouraging more implicit learning resulting in an update of an existing internal model.Acknowledgments: This research was supported by NSERC funding to the second author