The influence of awareness on explicit and implicit contributions to visuomotor adaptation

Abstract

Explicit (strategic) and implicit (unconscious) processes play a role in visuomotor adaptation (Bond & Taylor 2015; Werner et al. 2015). We investigated the contributions of explicit and implicit processes to visuomotor adaptation when awareness was manipulated directly versus indirectly, and ask how these contributions change over time. Participants were assigned to a Strategy or No-Strategy group. Those in the Strategy group were made aware of the visuomotor distortion directly. Participants were further subdivided into groups to train with a large (60°), medium (40°) or small (20°) visuomotor distortion, providing the potential for awareness to develop indirectly. Participants reached with their respective distorted cursor, followed by a series of no-cursor reaches to assess the contributions of explicit and implicit processes to visuomotor adaptation after every 30 reach training trials. Within the no-cursor reaching trials, participants reached (i) with any strategies they had gained during training (explicit + implicit processes), and (ii) as accurately to the target as possible (implicit processes). Results showed that implicit contributions to visuomotor adaptation were greatest in the No-Strategy group and took time to develop. Explicit processes were greatest in the Strategy group, increased with rotation size in the No-Strategy group, and remained consistent over time. Taken together, results reveal that there are notable differences in explicit and implicit contributions to visuomotor distortions depending on if, and how participants become aware of the perturbation. Moreover, the results highlight the importance of instructions when evaluating reaching performance in no-cursor trials, as they can modulate reaching errors.

Acknowledgments: This work was supported by a Discovery Grand provided by the Natural Sciences and Engineering Research Council of Canada (E. K. Cressman)