Using transcranial Direct Current Stimulation (tDCS) to investigate why faces are and are not special

Area of Science:

• Cognitive Neuroscience
• Visual Perception

Background:

• The face inversion effect, superior recognition of upright over inverted faces, suggests specialized face processing.
• Understanding the neural basis of this effect is crucial for cognitive neuroscience.

Purpose of the Study:

• To investigate the neural underpinnings of the face inversion effect using transcranial direct current stimulation (tDCS).
• To determine if the face inversion effect relies on a unique neural mechanism compared to other visual stimuli.

Main Methods:

• A double-blind, between-subject design with 96 participants was employed.
• Two experiments utilized a matching task with faces and checkerboards from a familiar prototype-defined category.
• Anodal tDCS was applied to the Fp3 brain area.

Main Results:

• Anodal tDCS eliminated the inversion effect for checkerboards in the sham group.
• The face inversion effect was significantly reduced, but not eliminated, by anodal tDCS.
• A residual face inversion effect suggests a face-specific component unaffected by the tDCS protocol.

Conclusions:

• The face inversion effect comprises both expertise-based and face-specific components.
• The applied tDCS protocol selectively impacted the expertise-based component, leaving a face-specific element intact.