Optimal eye-gaze fixation position for face-related neural responses

Area of Science:

• Cognitive Neuroscience
• Visual Perception
• Human Brain Imaging

Background:

• Facial feature salience, particularly eyes, is debated for early face encoding.
• Previous studies used artificial stimuli, lacking evidence for natural face processing.
• Understanding early face perception is crucial for cognitive neuroscience.

Purpose of the Study:

• To investigate if early face encoding in the brain is eye-driven using naturalistic stimuli.
• To determine the influence of gaze fixation on face-sensitive neural responses.
• To explore how face orientation affects optimal fixation points.

Main Methods:

• Simultaneous recording of scalp electroencephalogram (EEG) and eye gaze-fixations.
• Utilized a gaze-contingent paradigm with naturalistic face stimuli.
• Analyzed the N170 component, an early face-sensitive neural response.

Main Results:

• The N170 response was maximal when gaze fixation was centered on the nasion (nose bridge).
• For inverted faces, optimal fixation points were more variable, clustering around the mouth.
• This indicates early face encoding is not solely eye-dependent.

Conclusions:

• Early face encoding, indexed by N170, is influenced by fixation location, favoring the nasion for upright faces.
• A general upper-visual field advantage and template matching likely contribute to face perception.
• Findings challenge the notion that eyes are the primary drivers of early face processing.