Unconscious arrow stimuli do not influence motor performance automatically

Abstract

Visible arrow cues have been suggested to lead to reflexive motor responses (Kingstone and colleagues, 2002, 2009). In the current study, we examined the degree of automaticity of arrow evoked responses by presenting the arrows unconsciously. Specifically, we asked if prime arrows presented in a backward masking paradigm (and hence not seen by subjects) would influence responses even when they were irrelevant to the task (i.e. subjects were not supposed to respond to them). Subjects were instructed to reach to a centre target. If a large left (or right) visible 'mask' arrow was displayed, they were to modify their movements and land at the left (or right) target. If an arrow in the right (or left) direction was presented, subjects were to continue pointing to the centre target. Small left and right arrows, as well as neutral primes, preceded all large mask arrows. Results revealed that although subjects were not aware of them, primes influenced performance such that subjects completed a greater number of responses to the left target when the left prime was presented compared to the right and neutral primes. Arrow primes indicating the non-response (i.e. right (or left)) direction did not influence movements, resulting in similar movement kinematics on trials in which the neutral and right primes were displayed. Thus, unconscious, irrelevant arrow stimuli do not appear to influence reaching movements automatically, suggesting that they can be ignored.

Acknowledgments: This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), awarded to Erin K. Cressman.