Accuracy instructions modulate both visual and non-visual contributions to ongoing reaches


The control of ongoing goal-directed reaches is influenced by both visual and non-visual sensorimotor processes. Further, intentions to produce accurate movements influence reaching performance as well. However, it is not known how these improvements associated with accuracy-based intentions can be attributed to changes in movement planning and/or online control. Indeed, such improvements may influence both visual and non-visual online control processes. Using frequency domain analyses, the relative online contributions of such visual and non-visual sub-processes have been previously identified (e.g., de Grosbois & Tremblay, 2015; de Grosbois & Tremblay, 2016b; de Grosbois & Tremblay, 2017). The current study tested if the relative contributions of these online control sub-processes are influenced by the intention to be accurate. Reaching movements were completed in the presence of three experimental manipulations. First, vision during voluntary reaches was either provided or occluded. Second, high- and low-accuracy instruction sets were provided. And third, the predictability of visual information was manipulated through a blocked and randomized feedback scheduling. The results indicated that the contribution of online visuomotor processes (i.e., visual sub-process) was increased by the availability of online vision and the instructed intention to be accurate. In contrast, the non-visual sub-process was promoted in the absence of online vision, but suppressed when a randomized feedback schedule was implemented with instructions to be accurate. Ultimately, the intention to be accurate increases the relative contribution of vision-based online sensorimotor processes and can decrease that of non-visual online sensorimotor processes.

Acknowledgments: This research was supported by the Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation, the Ontario Research Fund, and a University of Toronto Graduate Student Fellowship.