Facing two faces: Defense activation varies as a function of personal relevance

- To model a group situation, two faces were differently oriented relative to observer.
- Defense activation varied as a joint function of facial expression and orientation.
- Threat-potentiated startle reflex increased with perceived personal relevance.
- This gradient was pronounced for angry faces and steeper in social anxious people.
- Social context determines defensive responding in person perception.

It can be unsettling to be watched by a group of people, and when they express anger or hostility, this can prime defensive behavior. In contrast, when others smile at us, this may be comforting. This study tested to which degree the impact of facial expressions (happy, neutral, and angry) varies with the personal relevance of a social situation. Modelling a triadic situation, two faces looked either directly at the participant, faced each other, or they were back to back. Results confirmed that this variation constitutes a gradient of personal relevance (directed frontally > towards > away), as reflected by corresponding defensive startle modulation and autonomic nervous system activity. This gradient was particularly pronounced for angry faces and it was steeper in participants with higher levels of social anxiety. Thus, sender-recipient constellations modulate the processing of facial emotions in favor of adequate behavioral responding (e.g., avoidance) in group settings.