Temporally differentiated modulation of emotional face processing by attentional resource availability: An ERP study

The interplay between top-down attentional control and bottom-up emotional capture remains debated, particularly in the late positive potential (LPP) time window. In the present study, we used mass-univariate analysis to examine whether task difficulty itself modulates late-stage emotional processing in an implicit task. In a dual-target rapid serial visual presentation (RSVP) paradigm, perceptual load was manipulated at T1, and at T2, fearful, happy, neutral, or face-absent stimuli were presented in a face-detection task. Emotional differentiation emerged during 148-372 ms and was not influenced by perceptual load, suggesting that emotional features were extracted relatively automatically. During the early LPP (400-600 ms), emotional differentiation was detected under low but not high load, suggesting that inconsistencies in emotion-related LPP effects reported in previous implicit-task studies may stem from differences in task difficulty. During the late LPP (600-800 ms), however, fearful expressions remained distinguishable from neutral expressions even under high load, indicating that resource limitations did not eliminate late emotional differentiation. Together, these findings provide compelling evidence that the availability of attentional resources differentially shapes the processing of emotional information in implicit tasks.