Motor-based prediction during preparation of hand movement modulates auditory processing in two distinct directions

Differentiating self-generated from externally induced sounds is crucial for survival. Predictions can be generated based on action-outcome contingency and suppress neural responses to sensory reafference for distinguishing the origin of stimuli. The action-outcome contingency can be flexible or relatively fixed (e.g., keypress could trigger various sounds vs. articulatory gestures generate corresponding speech sounds) and can be available during the entire course of action (including stages of intention, preparation and execution). Are motor-based predictions created equally based on different types of action-outcome contingency and during distinct stages of action? We conducted three EEG experiments to determine how motor preparation modulates auditory processing using a delayed keypress paradigm in which participants prepared to press a key to trigger a sound without knowing what key to press. In Experiment 1, keypress preparation showed overall enhanced N1 responses (∼100 ms), largest for syllables, but did not reveal any suppression effects. Experiment 2 replicated N1 enhancement and showed significant P2 suppression (∼200 ms) in response to auditory syllables, when participants were pianists who had extensive keypress-sound mapping experience. Experiment 3, when pianists were in their unfamiliar pairing of lab keys and familiar piano tones, again showed N1 enhancement, but the P2 suppression was absent. Together, these results suggest that preparatory motor prediction in an optional mapping can influence auditory processing in multiple directions and motivate a two-stage gain-to-attenuation hypothesis that may depend on the precision (reliability) of action-outcome associations.