INTRODUCTION: This study concerns the influence of non‑perceptual information on visual awareness. We focus on the contribution of action evidence to visual awareness ratings using single-pulse Transcranial Magnetic Stimulation (sp‑TMS). This study aims to inform the current debate on the cognitive and neural mechanisms underlying awareness. AIM(S): The first aim of the study was to investigate the influence of TMS-induced motor response on awareness ratings. The second aim was to establish whether TMS-induced motor evoked potentials (MEPs) measure the amount of accumulated evidence for a certain discrimination task response and differentiate the level of visual stimulus awareness. METHOD(S): By employing a stimuli identification task, we measured to what extent participants are sensitive to visual information and, using the Perceptual Awareness Scale (PAS), we collected participants’ subjective ratings of their visual experience of stimulus. In a within‑subject design involving 46 volunteers, the tasks were coupled with sp-TMS and electromyography to manipulate participants’ stimulus awareness assessment and record MEP. RESULTS: We observed higher PAS ratings in the primary motor cortex (M1) sp‑TMS condition than in the control condition, but only for responses congruent with the sp‑TMS. Identification response reaction times (RTs) in these conditions were higher than in the control condition. The MEP amplitudes increased together with the PAS ratings in sp-TMS congruent responses as compared to incongruent. We also observed that the sp-TMS condition is accompanied by prolonged RTs in the identification task. CONCLUSIONS: Motor response can be conceived as a factor that influences awareness. We also argue that MEPs might serve as an indirect measure to predict both perceptual and non-perceptual evidence accumulated to visual awareness ratings. Finally, we conclude that the integration of additional information that affects awareness ratings seems to require additional time, thus it was accompanied by prolonged RTs in the identification task. Our results suggest that stimulus‑related motor activity influences visual awareness, extending the classical view on how visual awareness is shaped.
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