The ecological signal value of faces: differential effects of threat-related expressions and evolutionarily significant social cues on recognition and source memory.

Extending the dimensional approach to emotion, emerging evidence suggests that facial expressions displaying discrete emotions modulate cognition according to their distinct ecological signal values. However, whether these divergent signals shape source memory processes remains unanswered. Here, we investigated whether angry, fearful, and neutral faces - varying across the evolutionarily significant social cues of sex and group membership (in-group vs. out-group) - differentially influence recognition and source memory performance. Following incidental encoding, participants completed a sequential source-monitoring test requiring confidence-based recognition judgments and forced-choice source decisions. While the emotional stimuli were equated for valence and arousal, a noteworthy portion of our findings indicates that memory is regulated by the communicative value and the threat potential of the expressions. Notably, a recognition advantage emerged for angry expressions, particularly among out-group targets, whereas a more liberal response bias was detected for angry male faces, demonstrating a mnemonic sensitivity to facilitate direct threat anticipation. Contrary to predictions, source memory accuracy was exclusively modulated by group membership, reflecting a robust in-group advantage regardless of the emotional signal or target sex. Collectively, this study illustrates the intricate interplay between emotional expressions and evolutionarily important cues, highlighting how mnemonic mechanisms differentially prioritise the multifarious facial signals to effectively guide adaptive behaviour.