Learning about faces: effects of trustworthiness on affective evaluation.

The results of two studies on the relationship between evaluations of trustworthiness, valence and arousal of faces are reported. In Experiment 1, valence and trustworthiness judgments of faces were positively correlated, while arousal was negatively correlated with both trustworthiness and valence. In Experiment 2, learning about faces based on their emotional expression and the extent to which this learning is influenced by perceived trustworthiness was investigated. Neutral faces of different models differing in trustworthiness were repeatedly associated with happy or with angry expressions and the participants were asked to categorize each neutral face as belonging to a "friend" or to an "enemy" based on these associations. Four pairing conditions were defined in terms of the congruency between trustworthiness level and expression: Trustworthy-congruent, trustworthy-incongruent, untrustworthy-congruent and untrustworthy-incongruent. Categorization accuracy during the learning phase and face evaluation after learning were measured. During learning, participants learned to categorize with similar efficiency trustworthy and untrustworthy faces as friends or enemies and thus no effects of congruency were found. In the evaluation phase, faces of enemies were rated as more negative and arousing than those of friends, thus showing that learning was effective to change the affective value of the faces. However, faces of untrustworthy models were still judged on average more negative and arousing than those of trustworthy ones. In conclusion, although face trustworthiness did not influence learning of associations between faces and positive or negative social information it did have a significant influence on face evaluation that was manifest even after that learning.