Automatic and intentional brain responses during evaluation of face approachability: correlations with trait anxiety

The judgment of the approachability of others based on their facial appearance often precedes social interaction. Whether we ultimately approach or avoid others may depend on such judgments.

We used functional magnetic resonance imaging to determine the neural basis for such approachability judgments and the relationship between these judgments and trait anxiety. Participants viewed ambiguous (i.e. neutral) or relatively unambiguous (i.e. angry, happy) faces, assessing either the approachability or the sex of the person depicted.

Neutral faces elicited more inconsistent responses within participants only during approachability judgment, suggesting ambiguous property as signals. The contrast pertaining to the interaction between task and face valence demonstrated activation in several areas, such that the left amygdala and medial, middle and inferior frontal gyri were responsive to angry faces when subjects were asked to recognize the sex (implicit task) and to neutral faces when required to discern the approachability (explicit task). Moreover, the blood oxygenation level-dependent change within the left amygdala in response to neutral faces during the judgment of approachability was positively correlated with participant trait anxiety.

These findings extend a proposed model of social cognition by highlighting the functional engagement of the amygdala in approachability judgments, which underlie an individual's sensitivity to ambiguous sources of probable threat.