How Trust Priming Modulate Economic Decision Making in The Ultimatum Game: An ERP Study

IntroductionThis study investigated the effect of priming with trusty words on participant's behavioral responses to fair/unfair offers in a modified ultimatum game (UG). Besides, neural correlates of behavioral responses in three situations (no priming, trust/distrust priming) were compared. Two well-known ERP components in UG recipients were analyzed including; the feedback-related negativity (FRN) and the P۳۰۰.MethodThe EEG was recorded from eighteen subjects, during UG playing task, using a ۳۲-channel Psychlab system. Before EEG recording, the participants were told that they would play as a recipient in the UG with a stranger in the other room as a proposer. Each participant played UG in three situations including; no priming, trust and distrust priming. The standard preprocessing pipeline was implied on the EEG data using EEGLAB ۱۴.۱.۱ To remove artifacts. Then FRN and P۳۰۰ components were extracted using the ERPLAB plugin. Subsequently, behavioral and neural responses at the three mentioned conditions were statistically compared using the repeated measure ANOVA and paired t-test as the post-hoc analysis.ResultsBehavioral data analysis, showed accepting rate was significantly affected by the type of offer and a higher acceptance rate was for fair as compared to unfair offers in all priming situations. These findings support the inequity aversion in human economical decision-making. The rate of acceptance in the non-priming situation decreased as compared to trust priming, because of the negative association the word trust may bring to the mind in the cultural setting of the study. The neural data analysis showed the FRN amplitude was more negative in distrust priming versus no priming at the frontal regions, and no significant difference was observed in fair versus unfair offers. No significant difference was observed for the P۳۰۰ component.ConclusionsBased on the FRN amplitude changes, we suppose distrust priming can more significantly influence the participant's fairness consideration.