Cognitive Neural Mechanisms Of Social Responsibility Research

In our real life, people always tend to conduct appropriately and adjust their behavior based on personal sense of responsibility, which generates from social prescription and moral rule. Social responsibility links personal behaviour with society and plays a key role in affecting an agent's emotional state following a decision. Responsibility attribution--determining who is responsible for what outcomes--underlies this process and is fundamental to the allocation of social resources. Recently, neuroscientists have become greatly interested in exploring the neural basis of social cognition and moral judgement. Generally, decision-making process can be devided into two parts, the decision phase and outcome evaluation phase. In the last ten years, plenty of ERP (Event-related Potentials) studies have focused on the outcome evaluation process. However, researchers have neglected the role of responsibility in such social decision-making tasks. Besides, we believe that responsibility not only exists in decision-making process, but also played an important role in social moral and legal judgement. Therefore, the present thesis in aimed to explore the cognitive and neural mechanism of these two kinds of responsibilities.The aim of experiment one was to manipulate participants'social responsibility in a decision-making task under a social context and to investigate whether the social responsibility will influence the brain activity of outcome evaluation. Specifically, we developed a novel group gambling task and tried to simulate social responsibility diffusion phenomenon in laboratory. In one condition, participants conducted the task with other two confederates (i.e. low responsibility condition) while they performanced the game individually for the whole group in another condition (i.e. high responsibility condition). We collected the brain activity signal when they received the final feedback and also asked them to finish a post-experiment questionnaire. Based on some previous behavioral, ERP and fMRI studies, we predicted that different sense of responsibility will influence the ERP components observed during the outcome evluation process. Results showed that compared to low responsibility condition, feedback stimuli in high responsiiblity conditon elicited larger fERN and P300. The further correlation analysis revealed that the fERN is significantly correlated with subjective rating of sense of responsibility:the higher responsibility sense partcipants have, the larger fERN was observed.The aim of experiment two was to replicate the main finding of experiment one. We asked participants to finish two kinds of gambling tasks. The only difference between these two tasks is that there is a rule in one task while no rule in another. Thus, participants could have different sense of controllability between two conditions. We predicted that different controllability will arouse different sense of responsibility, which in turn will influence outcome evaluation. Participants' brain potentials and post-experiment rating score will also be recorded. The results of experiment two replicated the main finding of experiment one:larger fERN and P300amplitude were observed in high responsibility condition compared to in low comdition and only the fERN amplitude was correlated with subjective rating scores.The above two experiments domanstrated that the sense of responsibility influnced reinforcement learning process, indexed by fERN. However, the neural basis of social responsibility attribution has yet to be well explored. According to the reinforcement learning theory, basal ganglia, ACC and some other areas are invovled in learning process. Our two ERP studies proved that the responsibility sense could modulate this learning system. Then our next question is that which part in the brain is responsible for social responsibility attribution? These two studies can't answer this quesition due to the low spatial resolution of ERP technology. Thus, in experiment three, we intended to explore the neural basis of responsibility process by fMRI technology. We modified the paradigam used in experiment one. Participants were still required to finish a group task with other two partners, however, they were always set to be the final person to do the last shot. We tried to manipulate participants'responsibility sense by different contexts and reward probabilities. The behavioral data revealed that our manipulation made sense to them:they reported the highest blame sense and highest praise sense in the highest responsibility condition. More importantly, the fMRI results showed that dMFC is related to responsibility processing, higher dMFC activation was observed when people felt higher responsibility sense.In the experiment three, different valence of feedback elicited differently stronger brain activation while responsibility related regions were relatively activated weekly. We assumed that the reason was that participants might pay more attention to monetary gain or loss information in such gambling tasks. We also concerned that the responsibility-related regions might be overlapped with prediction error relation regions. To solve these problems, we carried out the expriment four and tried to separate the reward process and responsibility attribution. In this experiment, participants finished a task with their teammates and received the team feedback and individual feedback sequentially. We found that the (right) temporoparietal junction (RTPJ) was associated with social praise sense while dorsal striatum and dorsal anterior cingulate cortex (ACC) might be related to reinforcement learning during the attribution processing.In the above mentioned studies, we focused on the social responsibility under a social context. To further understand the cognitive mechanism of responsibility, we also studied the social moral and legal responsibility judgement in experiment five. Previous researchers have neglected the difference between the "conductor" scenario and "bystander" scenario. Therefore, in this expeiriment, we intended to investigate how belief and outcome valence influence moral and legal responsibility judgement in these two scenarioes. Results demonstrated that moral and legal responsibility judgements were different in the "bystander" scenario while they were similar in the "conductor" scenario. Moreover, moral responsibility judgement was more sensitive to belief and legal responsibility judgement was more sensitive to outcome valence.In all, the present thesis provided some important scientific contributions:first of all, we found individual responsibility influence the fERN component during outcome evalaution process and provide first ERP evidence to prove individual responsibility modulate outcome evaluation. This finding also helps us to understand the functional significance of fERN. Secondly, we found several important regions of "theory of mind" involved in the responsibility processing and provided original neuroimaging evidence to understand the neural mechanism of responsibility attribution under complicated social context. Finally, we also have done a primary study in social moral judgement field and found some fresh results which might lead us to reconsider the current theory.