The Time Course of Attention Engagement in a Single-stream Rapid Serial Visual Presentation Design

When two stimuli are presented at the same spatial location in close temporal proximity-typically less than 500 msec apart-the second stimulus is often not perceived, a phenomenon known as attentional blink (AB). This striking failure of visual awareness is thought to reflect limitations in the allocation of attention for the selection and consolidation of visual input. While existing models of the AB differ in their predictions regarding when and why attentional engagement is required, no direct neural correlate has yet been identified to track this process during the AB. Here, we propose that the bilateral N2 posterior contralateral (N2pcb) component of the ERP time-locked to the second stimulus may serve as such a marker. To test this hypothesis, we reanalyzed data from our prior study [Dell'Acqua, R., Dux, P. E., Wyble, B., Doro, M., Sessa, P., Meconi, F., et al. The attentional blink impairs detection and delays encoding of visual information: Evidence from human electrophysiology. Journal of Cognitive Neuroscience, 27, 720-735, 2015], in which participants identified target letters embedded in rapid serial visual presentation (RSVP) streams of distractor digits. Each RSVP stream ended with either an unmasked letter (target-present trials) or a digit (target-absent trials). Subtracting ERPs elicited in target-absent trials from ERPs elicited in target-present trials revealed that the N2pcb component persisted even during the AB. These findings suggest that attentional engagement for the second target is largely preserved during the blink, indicating that a disruption of attention is not necessary for the AB to occur, and that post-attentional processing limitations likely play a major role-a conclusion consistent with a specific subset of current AB models.