Passing faces: sequence-dependent variations in the perceptual processing of emotional faces

Area of Science:

• Cognitive Neuroscience
• Social Psychology
• Psychophysiology

Background:

• Contextual factors significantly influence emotional facial expression processing.
• The temporal-dynamic aspects, specifically the sequence of neutral and emotional faces, remain under-investigated in face processing research.

Purpose of the Study:

• To investigate how the sequential order of neutral and emotional facial stimuli affects brain activity during face perception.
• To differentiate the roles of early posterior negativity (EPN) and late positive potential (LPP) in processing facial sequences and emotional interpretation.

Main Methods:

• Electroencephalogram (EEG) was recorded from 168 healthy participants.
• Participants performed a gender-discrimination task using sequences of angry and neutral faces.
• Event-related potential (ERP) analyses, including N170, EPN, and LPP components, were conducted.

Main Results:

• The N170 component showed strong emotional modulation, suggesting parallel visual encoding and emotional analysis.
• The early posterior negativity (EPN; 200-300 ms) was significantly influenced by preceding face sequences.
• The late positive potential (LPP; 400-600 ms) was less affected by sequences but reflected the net emotional interpretation.

Conclusions:

• The EPN appears to integrate contextual information from preceding faces into the perception of the current face.
• The LPP reflects the overall emotional interpretation of the current facial stimulus.
• Distinct ERP components (EPN and LPP) highlight separate processes in face analysis influenced by sequential context.