The Cognitive And Neural Mechanism Of The Self-control Effect On Risky Decision Making

Risky decision making refers to the individual weighing of benefits against costs in the situation of different options and probability(Kahneman,2003).Risky decision-making is one of the classic study of decision-making area.To make decisions is a significant function in our everyday life. Throughout life, most of the daily decisions are involved with some degree of risk. In fact, nowadays the dual systems model has been widely applied in the interpretation of risky behaviors(Casey & Jones, 2010; Casey, Jones,& Hare,2008). According to this model, risky behavior is the product of the interaction between two distinct neurobio logical systems:the "socio-emotional" system, which is localized in limbic area of the brain, including the VS, OFC, superior temporal sulcus(STS), medial prefrontal cortex(mPFC) and amygdala; the "cognitive control" system, which is mainly composed of the parietal and lateral prefrontal cortices(Ernst & Mueller,2008; Steinberg,2010). The model suggests that at early years(such as puberty), people are predisposed towards risky behavior because of an imbalance between early maturation of limbic emotional systems and slower maturation of PFC(Somerville & Casey,2010). Based on this dual system model, we understand that the ability of self-control has a significant impact on risky decision making. But we still have no idea about how self-control affect risky decision making. Therefore, the study examed, from the sight of self-control, individuals’ risk preference, and discussed the cognitive and neural mechanism of the self-control effect on risky decision making. By adopting the behavioral test and rs-fMRI technique, and with the classic experimental paradigm of risky decision making-wheel of fortune(WOF) task, this study mainly explores two questions:(1)the relation between self-control and risky decision, and the effect of reward magnitude, probability and their interaction on risky decision making; (2)the cognitive and the neural mechanism of self-control effect on risky decision making. Therefore, the study contained two experimental researches as follows:Research I adopted the WOF task and the self-control inventory. We expected that the scores of self-control were in negative correlation with the risk preference, and reward magnitude, reward probability and their interaction could predict risk preference to some extent. And then we would prove the three processes of risky decision making from the sight of behavioral experiment. The results showed that:(1) the scores of self-control were in negative correlation with risk preference;(2) the probability were in positive correlation with risk preference. With the increasing of reward probability, the acceptant rate increased. And between 20-50%(probability), the acceptant rate showed a sharp upward trend;(3)the reward magnitude were in negative correlation with risk preference;(4)the regression analysis showed that both reward probability and the interaction between reward magnitude and probability could jointly predict risk preference.The results indicated that the probability process and risk process(interaction between reward magnitude and probability)could jointly predict risk preference. But we couldn’t deny the effect of reward process. Conversely, the significant effect of the interaction between reward magnitude and probability reflected the importance of the balanced development between "cognitive control" and "socio-emotional" systems to risky decision making. In general, research I showed that self-control can affect risk preference;and reward probability, the interaction between reward probability and magnitude could jointly predict risk preference. So our research proved that risky decision making involved three processes:reward magnitude process, probability process and risk process.In research Ⅱ, rs-fMRI was adopted to study the neural mechanism of self-control effect on risk preference. The key method was, from the perspective of reward magnitude process, probability process and risk process, to explore self-control’s regulating mechanism on risky decision making. Behavioral results proved the conclusion of research I:the scores of self-control were in negative correlation with risk preference. Rs-fMRI data mainly found out that:(1) self-control scores were positively related with RDLPFC-LVS,RDLPFC-RaINS, RDLPFC-RdACC and RDLPFC-RSPL functional couplings;(2) the index of risk preference were in negative correlation with RDLPFC-LVS, RDLPFC-RaINS and RDLPFC-RSPL couplings;(3) the structural equation model(SEM) results suggested that the effect of self-control on risk preference was completely mediated by RDLPFC-LVS, RDLPFC-RaINS and RDLPFC-RSPL couplings.Combined, these results of research 1 and research Ⅱ, it can be found out that:(1) self-control can predict individuals’ risk preference. Risky decision making involved three processes:reward magnitude process, probability process and risk process;(2)Importantly, the SEM results suggested that those three functional couplings supported the covariation between self-control and risk preference.This study explored the cognitive and neural mechanism of self-control effect on risky decision making from the perspective of three processes of risky decision making, widening the study field of risky decision making and providing theoretical basis for intervention, thus is of important practical application values.