Prosocial Conformity In Games

Prosocial behaviors are voluntary acts intended to benefit others.Cultural and social norms encourage people to act prosocial behaviors.During past decades,many psychologists investigated prosocial behaviors.The majority of research on prosocial behaviors has involved direct and indirect observations of behaviors.Therefore,we know much about prosocial behaviors.However,we know little about the effect of social conformity in prosocial behaviors.In this thesis,we have three studies.Each study has two experiments.We used fMRI to study the effect of social conformity in trust decision and dictator decision and the neural mechanisms underlying the effect of social conformity in prosocial behaviors.Then we focused on individual difference in the effect of social conformity in prosocial behaviors.In study 2,we were interested in the moderating effect of social value orientation on the effect of social conformity in prosocial behaviors.In study 3,we studied moderating effect of interpersonal trust on the effect of social conformity in prosocial behaviors.In study 1,we have two experiments.In first experiment,we used psychological and neuroscientific methods to investigate brain activity in social conformity during a trust game.The behavioral results revealed that individuals are likely to be influenced by others' opinions and conform to the opinions of peers in a trust game.Subjects responded faster when they could see their peers' choices,especially when most group members decided to trust the trustee.The rate of trust was higher when participants found that the majority of group members trusted the trustee compared to in the baseline condition.Conversely,the rate of trust was lower when participants saw that most group members decided to keep the endowment(distrust)compared to in the baseline condition.Previous studies have shown that an individual's behavior can be influenced by the opinions of peers,even if the decision of the majority was against their own preference.The results of the present study indicated that the trust preference of individuals could be influenced by the opinions of peers.About the fMRI results,we analyzed the conforming behavior contrast(conformity vs.non-conformity)in trust information condition to capture the neural mechanisms underlying conformity effect in trusting behavior.Results shown that the trust information which successfully induced conformity in trusting behavior activated the brain regions such as bilateral parahippocampal gyrus,ventral medial prefrontal cortex,rostral cingulate zone,anterior cingulate cortex/ caudate head,middle occipital gyrus,middle frontal gyrus,middle temporal gyrus,postcentral gyrus and inferior parietal lobule.The psychophysiological interaction analyses showed that activity in the ventral striatum was accompanied by task-dependent(conformity > non-conformity)functional interaction with brain areas: medial prefrontal cortex,superior temporal gyrus,superior frontal gyrus,middle temporal gyrus and inferior temporal gyrus.The opposite contrast did not reveal any significant changes in functional connectivity.Taken together,these findings suggest that the underlying mechanisms of social conformity in trusting behavior may be similar to those implicated in reward learning.Agreement with the other group members might predict future acceptance from peer,which can also activate the reward system.Our results confirm results of previous studies that reported reward-related activity during social choices in interactive cooperation paradigms.In second experiment,we used a modified dictator game to investigate the effect of social conformity on making an equitable decision.We found that the effect of social conformity on equitable decision-making was influenced by the individuals' inequity aversion.Participants' decisions were influenced by equitable rather than inequitable group choices.To assess brain regions involved in the effect of social conformity in the equitable decision,we conducted a 2(offer type: selfish,generous)× 3(social conformity: selfish,generous,baseline)ANOVA.The interaction was significant in several brain regions,including the medial prefrontal cortex,dorsal medial prefrontal cortex,rostral cingulate zone,bilateral caudate,middle frontal gyrus,superior frontal gyrus,cingulate gyrus,inferior parietal lobule and postcentral gyrus.Post hoc contrast indicated that medial prefrontal cortex,dorsal medial prefrontal cortex,rostral cingulate zone,middle frontal gyrus and superior frontal gyrus were activated in the generous offer-selfish influence condition.The bilateral caudate were deactivated in the selfish offer-selfish influence.To identify brain regions involved in the effect of advantageous inequity influence,we compared selfish influence trials with baseline in the generous offer condition.As expected,advantageous inequity influence trials induced activation in the dorsal medial prefrontal cortex,caudate,middle frontal gyrus and inferior parietal lobule.In addition,we found that the neural response in the dorsal medial prefrontal cortex predicted subsequent conformity behavior in the generous offer-selfish influence condition.There was a significant positive correlation between the neural response in the dorsal medial prefrontal cortex and the rate of conformity behavior in generous offer-selfish influence decision.The psychophysiological interaction analysis showed that activity in the dorsal striatum was accompanied by task-dependent(advantageous inequity influence > baseline)functional interaction with brain areas: bilateral insula,supplementary motor area,middle occipital gyrus,cingulate gyrus and postcentral gyrus.A direct contrast of generous influence trials with baseline in the selfish offer condition showed significant activation of the bilateral medial prefrontal cortex,dorsal medial prefrontal cortex,rostral cingulate zone,insula,bilateral middle temporal gyrus,middle frontal gyrus,middle occipital gyrus and inferior frontal gyrus.We also found that the activation in the insula and rostral cingulate zone predicted individuals' conformity in the selfish offer-generous influence condition.Result showed a negative correlation between the neural response in the insula and the rate of conformity in selfish offer-generous influence decision.The other negative correlation was found between the neural response in the rostral cingulate zone and the rate of conformity in selfish offer-generous influence decision.By using psychophysiological interaction analysis,we found decreased functional connectivity between medial prefrontal cortex and insula,supplementary motor area,superior frontal gyrus,middle frontal gyrus,sub-gyral,cingulate gryus,dorsal anterior cingulate cortex,posterior cingulate gyrus,inferior temporal gyrus,middle occipital gyrus,postcentral gryus,cuneus,precuneus and bilateral lingual gyrus.These results indicated that the neural mechanisms underlying social conformity in an equitable decision may be similar to those implicated in social norms and reward processing.People often face mixed-motive social dilemmas in which their self-interest is at variance with what is best for their community.Previous studies have shown that people differ in fundamental ways in how they approach and interact in social dilemmas.Social value orientation has been defined as a personal trait that reflects how people resolve social dilemmas.The implications of individual differences in social value orientation refer to people's self-regarding versus other-regarding preferences.Researchers have noted that three social value orientations are common: individuals can be classified as prosocials,individualists,and competitors.Prosocials are defined as individuals who attempt either to maximize the welfare of others or to choose joint gain.Individualists prefer to maximize their own welfare,showing little concern with others' outcomes.Finally,competitors attempt to maximize the difference between their own welfare and others' outcomes.In study 2,we combined individual differences with social conformity and attempted to discover the effect of social value orientation and social conformity on prosocial behavior in a trust game and a dictator game.Prosocial behavior in the trust game could be motivated by strategic considerations whereas individuals' decisions in the dictator game could be associated with their social preference.One hundred thirty-six healthy right-handed participants completed experiment 3.One hundred sixteen participants fell into one of three social value orientations.The results indicated that the interaction between social value orientation and social conformity was significant.Prosocial individuals trusted the trustee at a significant higher rate than proself individuals in the baseline condition.In addition,prosocial individuals also trusted the trustee at a significant higher rate than proself individuals in the distrust condition.The difference between prosocials and proselfs in the trust condition was not significant.This result suggested that prosocials were less likely than proselfs to conform to the behavior of other group members when the majority of group members distrusted the trustee in the trust game.One hundred three healthy right-handed participants completed experiment 4.Ninety-five participants fell into one of three social value orientations.Social conformity effect was measured by the rate of allocate money to the receiver.The interaction between social value orientation,offer type and social conformity was significant.Regardless of the type of offer,proselfs allocated money to the receiver at a significantly higher rate in the generous influence condition than in selfish influence condition and in baseline condition.For prosocials,they allocated money to the receiver at a significantly higher rate in generous influence condition than in the baseline when the offer is generous offer.However,the difference between selfish influence condition and baseline was not significant.In addition,the difference between selfish influence condition and generous influence condition was also not significant.In the selfish offer condition,prosocials allocated money to the receiver at a significantly higher rate in the generous influence condition than in selfish influence condition and in baseline condition.The difference between selfish influence condition and baseline was not significant.These results suggested that,irrespective of the type of offer,in contrast to proselfs,prosocials were influenced more by others' generous choices than their selfish choices,even if the selfish choices were beneficial to themselves.The overall results demonstrated that the effect of social conformity appears to depend on individuals' social value orientation: that is,prosocials tend to conform to prosocial rather than proself behaviors.Previous studies indicated that high trusters are more likely to follow others' suggestions.They have been shown to cope more effectively with social stress than low trusters do.Previous studies have shown that individuals tend to conform to others.Some studies have demonstrated that conformity behavior could be modulated by personality traits.Although there are lots of studies about interpersonal trust and conformity,we still know little about how interpersonal trust might affect individuals' willingness to conform to others.To answer this question,we designed two experiments in study 3 to investigate the effect of interpersonal trust on informational conformity and normative conformity.We used Rotter's Interpersonal Trust Scale to measure participants' level of interpersonal trust.In the first experiment,participants played an invest game as an investor.They could see the choices of other group members before they made the decisions.A total number of 100 subjects participated in the experiment 5.Social conformity effect was measured by the rate of invest of participants.A two-way ANOVA revealed a significant main effect of the factor social conformity.Participants invested money to the trustee at a significantly higher rate in the invest influence condition than in the keep influence condition and baseline.The main effect of interpersonal trust was not significant.The interaction between interpersonal trust and social conformity was significant.The results indicated that high trusters invested money to the trustee at a significant higher rate than low trusters in the invest influence and kept money at a significant higher rate than low trusters in the keep influence condition.In experiment 6,participants made decisions about whether to allocate money to themselves,or to the partner.They could see the choices of other group members before they made decisions.A total number of 107 subjects participated in the experiment 6.Social conformity effect was measured by the rate of allocate money to others of participants.A three-way ANOVA revealed a significant main effect of the factor social conformity.The main effect of interpersonal trust was not significant.The interaction between interpersonal trust,offer type and social conformity was significant.The results indicated that low trusters allocated money to the partner at a significant higher rate than high trusters in the generous influence condition when the offer was generous.In conclusion,the results of the present study showed that individuals with high interpersonal trust were more likely to conform to others in an informational decision,whereas subjects with low interpersonal trust were more likely to conform to other group members in a normative decision.In present studies,we found that social conformity can influence individuals' prosocial behaviors.People tend to be prosocial when they see others acted prosocial behaviors,even if this kind of behavior against their profits.The fMRI results may reflect that the neural mechanisms underlying social influence on equitable decisions may be similar to those previously implicated in social norms and reward processing.We infer that people treat group's behavior as social norm.They tend to follow with this social norm.Additionally,we found social value orientation and interpersonal trust can moderate the effect of social conformity on the prosocial behavior.Prosocials tend to conform to prosocial rather than proself behaviors.Individuals with high interpersonal trust were more likely to conform to others in an informational decision,whereas subjects with low interpersonal trust were more likely to conform to other group members in a normative decision.