Facial trustworthiness affects outcome evaluation: an event-related potential study

Facial trustworthiness can influence trust behavior. The outcome may be concordant (a person with a trustworthy face who engages in reciprocal behavior) or conflicting (a person with a trustworthy face who does not reciprocate). This study investigated the temporal features of processing different outcomes following trustworthy or untrustworthy faces. Thirty-one college students participated in a decision-making task in which they were shown a face and were asked to judge whether the person would behave in a trustworthy or an untrustworthy manner in a hypothetical scenario, and feedback was then provided about the target person's behavior in the scenario, while the event-related potential of the electroencephalography of participants' brains was recorded. In the feedback presentation stage, there was a significant interaction between face type and feedback. Trustworthy faces with losses induced the largest feedback-related negativity (FRN), whereas trustworthy faces with gains induced the smallest FRN. For untrustworthy faces, there was no significant difference between losses and gains. Trustworthy faces with losses and untrustworthy faces with gains induced more positive P300. FRN is possibly sensitive to both negative outcomes and expectation violations. P300 is mainly sensitive to expectation violations. Individuals have high positive expectations for trustworthy faces. When the behavior of a trustee with trustworthy face was negative, so as to violate the trustor's expectation, it will elicit a more serious conflict in the mind of the trustor.