Covert manual response preparation triggers attentional modulations of visual but not auditory processing.

OBJECTIVE: We investigated whether covert unimanual response preparation triggers attention shifts, as postulated by the premotor theory of attention, and whether these result in spatially specific modulations of visual and auditory processing. METHODS: Visual response cues instructed participants to prepare to lift their left or right index finger in response to a subsequent target stimulus. Irrelevant visual or auditory probes were delivered to the left or right hand during the response preparation interval. ERPs were measured time-locked to cue onset, and time-locked to probe stimulus onset. RESULTS: Lateralised ERP components triggered during covert response preparation (ADAN, LDAP) were similar to components previously found during attention shifts. N1 components were enhanced to visual probes delivered adjacent to the cued response relative to those delivered to the opposite hand. Auditory probe ERPs were unaffected by manual response preparation. CONCLUSIONS: Shifts of spatial attention that are triggered during covert unimanual response preparation result in spatially specific modulations of visual but not auditory processing. SIGNIFICANCE: Results support the claim of the premotor theory that the preparation of manual responses is associated with attention shifts. However, such shifts are not based on purely supramodal processes, as they result in a modality-specific pattern of sensory modulations.