Event-related brain potentials distinguish processing stages involved in face perception and recognition

Area of Science:

• Cognitive Neuroscience
• Psychology
• Neuroimaging

Background:

• Face identification involves complex cognitive processes.
• Event-related potentials (ERPs) offer insights into the temporal dynamics of neural activity.
• Understanding face recognition is crucial for diagnosing and treating prosopagnosia.

Purpose of the Study:

• To investigate how different processing stages of face identification are reflected by ERP modulations.
• To examine the influence of stimulus repetitions and attentional set on ERPs during face processing.
• To differentiate neural correlates of early structural encoding versus later recognition processes.

Main Methods:

• ERPs were recorded in response to familiar faces, unfamiliar faces, and houses.
• Participants performed a target detection task (Part I) or engaged in directed/undirected attention tasks (Part II).
• Stimulus repetition and attentional manipulation were employed to probe face processing stages.

Main Results:

• The early face-specific N170 component was unaffected by face familiarity.
• Familiar faces elicited enhanced negativity (N400f) and positivity (P600f) compared to unfamiliar faces, with parietocentral distribution.
• These effects were attenuated by repetition and modulated by attention; N400f disappeared, but P600f persisted when attention was divided.

Conclusions:

• The N170 reflects pre-categorical structural encoding of faces.
• The N400f and P600f likely indicate subsequent face recognition processes.
• Impaired structural encoding, as seen in prosopagnosia, disrupts face identification, evidenced by absent N170 and later ERPs.