Why is the N170 enhanced for inverted faces? An ERP competition experiment

Area of Science:

• Cognitive Neuroscience
• Visual Perception
• Neuroscience

Background:

• The N170 component of event-related potentials (ERPs) is larger for inverted than upright faces.
• Two hypotheses explain this: increased processing difficulty within existing neural populations or recruitment of additional neural mechanisms.

Purpose of the Study:

• To investigate whether inverted face processing recruits additional neural mechanisms or augments activity in existing ones.
• To differentiate between two competing hypotheses explaining the N170 amplitude difference between upright and inverted faces.

Main Methods:

• Employed an ERP competition paradigm to measure the effect of context stimuli on target stimulus ERPs.
• Experiment 1: Upright target face with upright face, inverted face, or non-face context.
• Experiment 2: Inverted target face with upright or inverted face context.

Main Results:

• Replicated the ERP competition effect for faces with upright targets.
• Found similar competition effects for upright and inverted face contexts when targets were upright.
• Observed a larger competition effect for inverted targets in an inverted face context compared to an upright face context.

Conclusions:

• Findings support the hypothesis that inverted face processing recruits additional neural mechanisms.
• Suggests recruitment of additional neural mechanisms occurs as early as the N170 time window.
• Highlights distinct neural processing for upright and inverted faces.