Facial Trustworthiness Affects Individual Decision-making Behavior:An ERP Study

The economic theory "hypothesis of rational man" believes that individuals make rational decisions when they were engaged in economic activities,it's a rational behavior after judgment and calculation,and will not be blind or emotional.However,in fact,individuals often take into account other factors as well as interests when making decisions,and the faces of others may also influence their decision-making behavior.In this study,the ultimatum game paradigm and its variants were used to investigate the decision-making behaviors made by different game partners and highly simulate the economic decision-making activities in real life.In this paper,based on the previous studies,the event-related potential(ERP)technique was used to investigate the decision-making behavior and process of the subjects from different angles,and the influence of face trustworthness on individual decision-making behavior was discussed.In the first experiment,we used Facegen software to adjust the physiological structure of neutral face to change its trustworthiness,and we got two kinds of pictures with the level of face trust,and subjects were asked to rate their trustworthiness.The results show that there was a significant difference between the images of high and low face trustworthiness,which validated the face trustworthiness model proposed by Alexander et al.At the same time,it provides experimental materials for subsequent experiments.In the second experiment,the influence of face trustworthness on individual decision-making behavior was investigated.The high and low-trusted face pictures obtained in experiment 1 were taken as distributors in the game,and the distribution scheme presented was "fair" and "unfair".The results showed that low-trusted faces induced higher LPC amplitudes in the face recognition process.In addition,the face trustworthiness of the proposer influenced the decision-making behavior of the individual,and the "highly trusted proposer" urged the subjects to make more acceptance behavior.At the same time,"highly trusted proposer" weakens the individual's sensitivity to fairness,and under the group of "High trusted proposer",the amplitude of FRN induced by different level of distribution plan has no difference effect of "null".On the basis of experiment 2,experiment 3 improves the experimental paradigm.The face pictures obtained in experiment 1 were added to the game task as the role of no-right third party,and the influenced of the trust degree of the third party on individual decision-making behavior was investigated.The face picture of the experiment had two levels: "high credibility" and "low credibility",and the distribution scheme was divided into "fair /fair(4-4-4)" and "fair / unfair(7-4-1)"."unfair / fair(7-1-4)" and "unfair / unfair(10-1-1)" levels.The results showed that "highly trusted third party" causes individuals to produce more altruistic behavior in decision-making.When the third party was subjected to unfair treatment("7-4-1"),the individual produced a more negative FRN amplitude in the face of the " highly trusted third party " condition,and the individual is more willing to consider about the " highly trusted third party ".At the same time,"low trusted third parties" were able to reduce attentive resource allocation to unfair allocation schemes,and individuals faced unfair allocation schemes("7-1-4" and "10-1-11").The amplitude of P300 induced by "low trusted third party" was significantly smaller than that of "highly trusted third party".The experimental results of this paper showed that whether in a double game or in a multi-person game,the degree of trust of the face can influence the decision-making behavior of the individual.Individuals with highly trusted faces tend to have an advantage in social economic activities,and people tend to cooperation with individuals with highly trusted faces,and high trusted faces can reduce the fairness sensitivity of individuals.Individuals with low trusted faces are often at a disadvantage and their interests are often ignored by others.In social and economic activities,face trustworthiness influences our decision-making behavior subtly.