Brain laterality and the subliminal perception of facial expression

Area of Science:

• Cognitive Neuroscience
• Visual Perception
• Psychology

Background:

• Facial expression recognition is crucial for social interaction.
• HemisphericSpecialization theories suggest differing roles for the left and right brain hemispheres in processing visual information, including faces.

Purpose of the Study:

• To investigate the influence of visual field presentation on face detection and emotion recognition.
• To explore whether emotional facial expression processing occurs outside of conscious awareness.

Main Methods:

• Presenting faces with varying emotional expressions in either the left or right visual field alongside a visual noise stimulus.
• Varying stimulus presentation durations to assess both above and below conscious perception thresholds.
• Employing dual forced-choice tasks requiring participants to identify face location and emotional expression.

Main Results:

• A significant left visual field advantage was observed for accurately locating the presented faces.
• While suggestive, evidence for right hemisphere superiority in processing facial emotion itself was limited.
• Crucially, participants could identify facial emotions significantly above chance even when face location detection was at chance level (i.e., unconscious processing).

Conclusions:

• Facial emotion recognition can occur effectively even without conscious awareness of the face itself.
• The findings suggest a dissociation between conscious face detection and subconscious emotional processing.
• This implies that the brain can process and interpret emotional cues from faces at a level below conscious perception.