Modulation of face processing by top-down attention: Insights from early ERP waveforms

The face fusiform area (FFA) plays a pivotal role in face recognition, yet the precise timeline of its activity remains debated. Using EEG, we conducted three experiments to investigate how expectancy-consistent versus expectancy-inconsistent visual stimuli influence processing dynamics. Participants viewed images of faces, houses, and tools (Experiment 1), celebrity faces (Experiment 2), or animal faces (Experiment 3), preceded by a priming question. Notably, both conditions presented identical visual stimulation, ensuring that observed differences stemmed from cognitive processing rather than sensory input. Our results from Experiments 2 and 3 reveal that while the initial 150 ms period, crucial for unconscious face detection, remained unaffected, subsequent processing exhibited a delay of several milliseconds for expectancy-inconsistent stimuli, indicating additional processing time required for unexpected recognition. Importantly, no significant differences were observed in Experiment 1, where less demanding tasks or generic mental imagery were used, suggesting that the priming effect was not as pronounced in this context. These findings underscore the critical role of the period immediately following the first 150 ms in face identification and individuation, highlighting the influence of top-down attention on face recognition dynamics. This study provides novel insights into the temporal dynamics of face processing and the neural mechanisms underlying top-down attentional modulation.