N400-like potentials elicited by faces and knowledge inhibition

Area of Science:

• Cognitive Neuroscience
• Psychology
• Neuroscience

Background:

• The brain's processing of complex stimuli, like faces, can lead to errors, activating both accurate and inaccurate representations.
• Inaccurate facial representations are hypothesized to be more frequent or intense for unfamiliar compared to familiar faces.
• Top-down mechanisms influence stimulus processing, favoring context-congruent representations and increasing activation for expected known faces.

Purpose of the Study:

• To test the hypothesis that the N400 component of event-related potentials (ERPs) reflects knowledge inhibition.
• To determine if this hypothesis explains the N400-like potential observed when processing faces.
• To investigate how context expectancy influences N400-like potentials in face recognition.

Main Methods:

• Recorded event-related potentials (ERPs) while participants viewed known and unknown faces.
• Manipulated the proportion of known faces within experimental blocks to alter expectancy for known faces.
• Analyzed N400-like component amplitudes in relation to face familiarity and contextual expectancy.

Main Results:

• N400-like component amplitudes were larger for unknown faces than for known faces, indicating greater inhibition.
• Contextual expectancy significantly modulated N400-like amplitudes, with larger effects for unknown faces.
• Increased inhibition was observed in blocks rich in known faces, particularly for unfamiliar faces.

Conclusions:

• The N400 component likely reflects the inhibition of knowledge during face processing.
• Contextual expectancy plays a crucial role in modulating inhibitory processes during face recognition.
• These findings support a model where the N400 indexes cognitive control mechanisms engaged during perception.