Is a neutral face really evaluated as being emotionally neutral?

Area of Science:

• Cognitive Neuroscience
• Affective Science
• Psychology

Background:

• Functional neuroimaging studies frequently use neutral faces as a baseline.
• The emotional valence of neutral faces in research is often assumed, not empirically verified.

Purpose of the Study:

• To investigate whether prototypical neutral faces are implicitly evaluated as neutral.
• To determine the potential impact of neutral face stimuli on emotional processing research.

Main Methods:

• Utilized the Extrinsic Affective Simon Task (EAST) with 21 subjects.
• Presented juxtaposed standardized facial pictures, including color-filtered positive, negative, and neutral faces.
• Subjects classified target faces based on filtered color (blue vs. green) while attribute stimuli (positive vs. negative) were classified by valence.

Main Results:

• Responses to positive faces aligned with positive emotions, and negative faces with negative emotions.
• Responses to neutral faces were unexpectedly similar to those for negative faces.
• Responses to positive/negative mixed faces were undifferentiated.

Conclusions:

• Prototypical neutral faces may be implicitly evaluated as negative, challenging their use as a neutral baseline.
• The use of neutral faces as a baseline in functional neuroimaging may introduce experimental confounds.
• Re-evaluation of baseline stimuli in emotion research is warranted to ensure accurate findings.