Objective: The aim of our study is to better delineate the role of personalities in economic decision-making by investigating the role of basic individual personality traits as factors potentially affecting the willingness-to-share during an iterated Ultimatum Game (UG). During such task the participants played alternatively the role of proposer and responder in block series. We studied the correlation between brain activity and personality traits by means of Event-Related Potentials (ERPs) recorded during the whole decision-making process.
Methods: We analyzed the performance, the reaction times and the ERPs of N=28 participants who played alternatively, in six block series, the role of proposer (90 trials overall) and responder (90 trials overall), in an iterated Ultimatum Game (UG). Personality traits were assessed using the HEXACO-60 personality questionnaire. For each profile we analyzed the total amount of money earned by each participant playing the role of proposer and responder and the reaction times to each value of the offer made and received. For each personality trait we separated two groups of subjects showing the highest and lowest scores and we analyzed the grand averaged ERPs during both experimental conditions.
Results: Participants were playing the role of proposer they were earning (219.4+/-5.7) significantly less than their opponent player (278.6+/-15.9), F (1,54) = 12.26, p < 0.01. Then, in our experimental paradigm participants gained more when they acted as responder (one-way repeated measures ANOVA, F (1, 27) = 283.46, p < 0.001). Differences of ERPs response, in particular FRN (Feedback-related Negativity), was clearly characterizing the two roles played by the participant. Conscientiousness was positively correlated to Honesty and was the most salient personality trait. Participants with a high score of conscientiousness exhibited a much larger FRN in the frontal areas.
Conclusions: These results suggest that patterns of brain activity can be associated with specific personality trait and behavioral response during an iterated Ultimatum Game. Our study contributes to the understanding of brain circuits involved in decision-making in a strategic social environment used to discriminate between different types of fairness tested against willingness-to-share.
Acknowledgements:
This study was funded by the Swiss National Science Foundation, grant nb. CR1311-138032.