Abstract
Voluntary and involuntary attention are traditionally studied as separate types of attention, although they often interact in everyday situations to jointly influence perceptual processing. Here, we developed a hybrid attention task that uses peripheral auditory cues that capture attention reflexively but also carry predictive information about the location of a subsequent visual target, and examined EEG activity elicited by these cues to tease apart neural effects of voluntary and involuntary attention. Participants discriminated the tilt of a visual target which was preceded by a peripheral auditory cue presented from the left or right side. In Experiment 1 (N=16), the peripheral cues were either informative of the target location (80% valid) or not (50% valid). In Experiment 2 (N=14), the informative peripheral cue was compared to an informative symbolic cue presented centrally (both 80% valid). Across all conditions, participants showed higher target discrimination accuracy for validly versus invalidly cued targets (all ps < .008). Peripheral cues elicited increased neural activity in visual cortex contralateral to the cued side regardless of cue informativity, observed as a slow positive deflection ~260–400ms after cue onset (all ps > .002). This early positive wave was absent for informative symbolic cues, indicating that it reflects a unique signature of the reflexive orienting of attention. Critically, only informative cues elicited a sustained decrease in contralateral alpha power (~10Hz) that emerged rapidly for peripheral cues but was delayed for symbolic cues, suggesting that alpha activity plays an important role in biasing visual cortex activity in preparation of an expected visual target. Together, these results demonstrate a dissociation between the neural effects of involuntary and voluntary attention that depends on cue format and informativity of the cue, and suggest that the deployment of involuntary attention can hasten the sustained visual excitability engaged in anticipation of an impending target.