Interplay of action-based prediction and top-down attention: EEG evidence for joint modulation of late perceptual processing.

Voluntary action shapes our perception through sensory predictions of its consequences. These predictions are thought to inhibit perceptual processing of predicted outcomes, leading to sensory attenuation. However, some studies have reported findings that contrast with this effect, suggesting that the influence of predictions may reflect, or interact with, attentional processes. Here, we investigated the interplay of action-based prediction and top-down attention on early and late perceptual processing, with prediction and attention referring to the likelihood of a sensory event and its behavioral relevance, respectively. Electroencephalography (EEG) was recorded while participants viewed two sequential gratings. The orientation of the first was either predicted and self-generated or unpredicted and externally generated. Participants judged the tilt direction of the second grating relative to the first but responded only when the grating appeared in a task-relevant color. EEG analyses revealed no modulation of early visual potentials (N1a), but modulations at later processing stages. Specifically, the P3b exhibited reduced amplitude for predicted compared to unpredicted stimuli, but only when they were task-relevant, whereas task-relevance enhanced the P3b only for unpredicted stimuli. Interestingly, multivariate pattern analysis showed significant temporal clusters for decoding the grating's orientation exclusively for predicted and task-relevant stimuli, although decoding performance did not significantly differ between conditions. Furthermore, predicted and task-relevant stimuli elicited faster behavioral responses, with prediction-related P3b latency differences correlating with reaction-time differences. Overall, converging findings from the P3b, multivariate, time-frequency and behavioral analyses provide suggestive evidence that top-down attention and action-based prediction may jointly facilitate late perceptual and decision-related processing.