Studies On Sequential Risky Decision Making And Regret Of Individuals With Different Risk-taking Propensity

People's risky decisions are usually affected by individual and situational factors.Among the individual factors,the risk-taking propensity reflects the attitude of an individual when facing risk,and thus can predict his/her risk-taking behaviors.Among the situational factors,risk situation will directly affect individuals' risk-taking behaviors.Studies found that individuals with higher risk-taking propensity behaved more riskily in sequential risky decision-making.Moreover,the risk situation has different effects on risky decisions made by individuals with different risk propensity.However,these studies failed to investigate the corresponding emotional response and its effect on subsequent decision-making,therefore could not answer why individuals with different risk-taking propensity make different risky choices.There were two viewpoints in previous studies concerning this question: 1)individuals with higher risk-taking propensity tend to be riskier to seek positive sensation;2)individuals with different risk propensity have different rational evaluation on reward and loss,and individuals with higher risk propensity take risks to obtain higher reward.It remains unclear which view is more in line with the facts.To clarify this issue,the current paper combined behavioral experiments,fMRI technique and morphological analysis to systematically examine the risk-taking behaviors,regret,the effect of regret on subsequent decisions,and the related brain responses in individuals with different risk propensity.This paper used a sequential risk-taking task,which simulate the real world decision-making and can effectively quantify risk-taking behaviors and regret responses induced by risky decision.In the task,eight boxes are presented on the screen at the beginning of each trial,with seven boxes containing a reward(gold)and one random box containing a punishment(devil).The participants should press buttons to consecutively open boxes from left to right side and decide when to stop.Once the participants open the box containing the devil,the trial ends and the goldcoins obtained by the round will be cleared;if the participants stop unpacking,they will get the corresponding gold coins,and know the position of the devil and the number of gold coins that have not been obtained in the round.There are four studies in the paper.Study 1 includes experiment 1 and experiment2: experiment 1 measures the risk propensity of the participants and divides them into the adventurous group and the conservative group,and then examine the risk-taking behaviors,regret and the effect of regret on subsequent decisions for each group;experiment 2 verifies the results of experiment 1,and further adopts fMRI technique to investigate the brain activation in two groups.Study 2 includes experiment 3 and experiment 4: experiment 3 examines the risky decision-making and regret under high/low risky situations in two groups;based on the experiment 3,experiment 4 uses fMRI technique to explore the between-group difference in brain activation under high/low risk situations.Study 3 and 4 respectively use morphological analysis and regional homogeneity method to investigate the differences between the adventurous group and the conservative group in the gray matter volume and spontaneous brain activity at rest,elaborating the distinctions between individuals with different risk propensity in the brain structure and function and their relationship with risk-taking behavior.Through the studies above,the results in this paper are summed as follow: 1)on risk-taking behavior,the adventurous group is riskier than conservative group in sequential risky decision making.After introducing different risk situations,the adventurous group is more conservative under high-risk situation(large magnitude of reward/loss)than low-risk situation(small magnitude of reward/loss),while the conservative group is conservative under both situations;2)on regret response,the two groups show the same emotional response pattern: in the gain trials,the degree of regret gradually decreases as the real gain percentage increases;in the loss trials,the feeling of regret gradually increases as the loss increases.Additionally,aftermanipulating the risk situations,the two groups feel more regret under high-risk situation than that in low-risk situation in the loss trials;the adventurous group feel more regret under high-risk situation than that in low-risk situation,while the conservative group exhibit no significant difference between the two risk situations in the gain trials;3)on the effect of regret on subsequent decisions,the two groups can both adjust subsequent decisions based on regret under different risk situations: the more regret participants feel when facing miss chances,the riskier they will be in the subsequent trial;the more regret participants feel when facing loss,the more conservative they will be in the next trial;4)on brain responses,as the outcome gets better or the feeling of regret decreases in gain trials,the activation of ventral striatum increases in both groups,and the activation of insula increases only in the conservative group.Moreover,compared with the high-risk situation,the adventurous group has a stronger functional connectivity between the ventral striatum and the prefrontal cortex under the low-risk situation.The conservative group shows no difference in functional connectivity under different risk situations.Additionally,the gray matter volume and spontaneous brain activity of the ventromedial prefrontal cortex are significantly increased in the adventurous group than the conservative group,and the spontaneous brain activity is positively correlated with the participant's risk-taking behavior.In summary,by using a sequential risk-taking task,this paper systematically examines the dynamic process of risky decision making of individuals with different risk propensity both on behavioral and neural level and draws conclusions that although the adventurous group tends to be riskier than the conservative group,these two groups display the same pattern in regret responses and the effect of regret on subsequent decisions,and the adventurous group becomes conservative when facing a large magnitude of reward/loss(high-risk situation).This may suggest that the risky decision of individuals with higher risk propensity is much based on rationalevaluation of reward/loss rather than simply sensation seeking.These findings are beneficial to understand the individual's risk-taking behavior,and provide a new perspective for future studies on risky decision-making.