The Express Sensorimotor Response Selects Visual Features Based On Instruction

David Youhanna Mekhaiel, The University of Western Ontario

Abstract

In time-sensitive situations, orienting reflexes allow us to move rapidly in response to stimuli. The express sensorimotor response (ESR) is an orienting reflex presenting as a brief burst of muscle recruitment. Previous studies have identified commonalities between ESRs and express saccades, another orienting reflex.

In this study, we investigate if ESRs share in a characteristic of express saccades: preference for faces. In separate blocks, participants were instructed to reach toward one of two simultaneously appearing targets: a face and another image. Muscle activity in the pectoralis major muscle of the reaching arm was recorded using skin surface EMGs.

We found that the ESR, occurred in greater amplitude towards the instructed target, regardless of whether the instructed target was a face or not. While we found no evidence that ESRs preferer faces, our surprising finding demonstrates that ESRs can be modified by top-down modulation to identify stimulus features based on instruction.