AbstractCyclical upper-limb movements can involuntarily deviate from the primary movement axis and into a secondary axis when the performer concurrently observes incongruent biological motion. The current study examined the influence of the observed environmental context on movement interference. Participants executed continuous horizontal arm movements while observing horizontal (congruent) or curvilinear (horizontal with an incongruent vertical component) movements. The observed movements were executed with small or large objects posing as an obstacle or a distractor. For curvilinear movements, the obstacle was displayed within movement space preventing horizontal movement meaning the observed movement was rational. On the other hand, the distractor was displayed below movement space meaning the observed movement was irrational. For horizontal movements, the obstacle and distractor were located below movement space, but in the same relative location as the curvilinear movements. It was found that, overall, the incongruent curvilinear movements generated greater deviation into the secondary axis than the horizontal movements. Although there were no systematic differences between contexts for the curvilinear movement, there was greater deviation when observing horizontal movements with the large obstacle than for other contexts. This latter finding is interpreted to indicate that the performer recognized and internalized the potential collision that was being observed. These findings indicate the environmental context can modulate motor contagion. Moreover, the differential effects between congruent and incongruent movement deviations suggests a role of matching observed and executed actions, and supports the view of a dynamic interplay between action and movement intentions (Ondobaka et al., 2012).
Acknowledgments: We would like to thank Nathan Foster for his assistance in creating the visual stimuli. This research was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC).