The Impact of Attentional Resources on Emotional Expressions Revealed by Event-Related Potentials

The prioritized processing for emotions has been found to modulate the N170, Early Posterior Negativity (EPN), and Late Positive Potential (LPP) within the processing of facial expressions. However, existing evidence on how available attentional resources affect the emotional modulation of these ERP components remains inconsistent. To investigate this issue, we precisely controlled the perceptual load of the first target (T1) in a dual-target rapid serial visual presentation (RSVP) task, aiming to modulate the attentional resources available for processing emotional expressions (happy, fearful, neutral) at the second target (T2). Our results revealed the main effects of emotion in the 180-280 ms and 400-800 ms intervals, which were consistent with the early-stage processing of emotional expressions, as well as the elaborate, late-stage processing. During 320-400 ms, the amplitudes were more negative for high compared to low load conditions, representing a bottleneck in visual processing. The interactions between emotion and perceptual load were observed for the late LPP interval (600-800 ms). Specifically, the processing of happy expressions was modulated by perceptual load levels, whereas fearful expressions exhibited robust prioritized processing even under limited attentional resources. Overall, the present study revealed that the early-stage processing of emotional expressions operates automatically due to their high biological salience. In contrast, late-stage processing relies on the available attentional resources, with fearful expressions requiring minimal attentional resources due to their evolutionary significance.