Expectation modulates the preferential processing of task-irrelevant fear in the attentional blink: evidence from event-related potentials.

Background: Reporting the second of the two targets is impaired when it occurs 200-500 ms after the first, the phenomenon in the study of consciousness is the attentional blink (AB). In the AB task, both the emotional salience and the expectation of the second target increase the likelihood of that target being consciously reported. Yet, little is known about how expectations modulate the prioritized processing of affective stimuli. We examined the role of expecting fearful expression when processing fear in an AB task. Participants were presented with an AB task where the 2nd target (T2) is either a fearful face or a neutral face, and had to report the target's gender. The frequency of fearful to neutral faces on a given block was manipulated, such that participants could either expect more or less fearful faces.

Results: In the Experiment 1, we found that fearful faces were more likely to be recognized than neutral faces during the blink period (lag3) when participants were not expecting a fearful face (low fear-expectation); however, high fear-expectation increased the discrimination of fearful T2 than neutral T2 outside the blink period (lag8). In the Experiment 2, we assessed ERP brain activity in response to perceived T2 during the blink period. The results revealed that fearful faces elicited larger P300 amplitudes compared to neutral faces, but only in the low fear-expectation condition, suggesting that expecting a fearful expression can suppress the processing of task-irrelevant facial expression and unexpected fearful expression can break through this suppression. Fearful T2 elicited larger vertex positive potential (VPP) amplitudes than neutral T2, and this affective effect was independent of fear-expectation. Since no effect of expectation was found on the VPP amplitude while P300 exhibited significant interaction between expectation and expression, this suggests that expectations modulate emotional processing at a later stage, after the fearful face has been differentially processed.

Conclusions: These results provided clear evidence for the contribution of the expectation to the prioritized processing of second affective stimuli in the AB.