Investigating Facial Expression Processing during Fast Periodic Visual Stimulation using Highly Variable Stimuli

Facial expression recognition is a fundamental aspect of human social interaction, enabling effective communication and emotional understanding. Fast Periodic Visual Stimulation (FPVS) paradigms have recently emerged as a powerful approach for studying facial expression processing. However, previous studies often utilized identical base stimuli, making it difficult to disentangle neural responses to low-level perceptual differences from those reflecting conceptual discrimination of emotion. By introducing variability in our stimuli, we aimed to overcome these limitations and investigate neural responses to facial expressions of anger, fear, happiness, and sadness. Using EEG, robust oddball responses were observed across participants at both individual and group levels, demonstrating the paradigms sensitivity even with brief recordings and limited post-processing. Significant neural responses were detected across key regions of interest, with the right occipito-temporal region showing the strongest activity, consistent with its role in high-level facial expression processing. This study highlights the effectiveness of the FPVS paradigm for examining emotional processing using naturalistic stimuli and provides a framework for future research into neural mechanisms underlying facial emotion recognition in diverse and pathological populations.