Temporal dynamics of trustworthiness perception.

Behavioral and neuroimaging studies suggest that the attribution of trustworthiness to faces relies on emotional and structural cues. Attributions happen spontaneously and very rapidly but the precise temporal dynamics of the underlying processes are not known. We investigated the temporal dynamics of trustworthiness perception by employing scalp recorded event related potentials and evaluating effects on components previously implicated in face processing: P1 (positive component ~100 ms post-stimulus), N170 (negative deflection sensitive to faces) and a posterior-occipital negativity~230 to 280 ms (early posterior negativity-EPN). Participants judged the gender and trustworthiness of female and male images manipulated to look either more or less trustworthy. The results indicated that facilitated behavioral processing of socially important stimuli-in particular males that looked untrustworthy (and should be avoided) but also females that looked trustworthy (and who might therefore be useful in cooperative ventures)-was reflected in an increased negativity of N170 amplitude over the right hemisphere. Additionally, trustworthiness continued to modulate the amplitude of the negative deflection~230 to 280 ms post-stimulus during explicit judgments of trustworthiness but not during gender judgments. The results suggest that negativity accompanies the relevance of the faces (female trustworthy and male untrustworthy) that are important to remember for future social interactions.