Research On The Mechanism Of Risk Decision Making Based On Decision Neuroscience

Decision neuroscience is an emerging frontier discipline and a new growing point in the field of management science. It is an interdisciplinary field that derives from the recent development of the research in traditional behavioral decision making. By combining with the recent advance of the decision science in management science, cognitive science as well as psychology, decision neuroscience trys to adopt the neuroimaging technique to study the processing mechanism of human being's decision behavior, thus opening the "black box" of the brain. By virtue of understanding the neural processing of the decision making to slove the mechanism of decision making on the level of neuroscience, decision neuroscience will revisit the traditional behavioral decision making model and provide some empirical evidence for the reconstruction of the theoretical framework and normative basis of the decision making model.Risk decision making or decision making under risk is an important theme of decision science research. Behavioral decision making scientist Daniel Kahneman won the 2002's Nobel Laureate for his great contribution to the risk and uncertainty study. In the field of decision neuroscience, the director of the decision neuroscience lab in Unviersity of Arizona, America put forward in the "Decision neuroscience: New directions in studies of judgment and decision making" that there are two topics that deserve exhaustive exploration, one is the individual decision making and the other is social decision making, and the risk decision making is the main topic for individual decisions.The current studies take the processing procedure of the risk decision making as an object and utlize two neuroimaging techniques, the functional magnetic resonance imaging and even-related potential as the methods. These studies trys to observe the neural basis of the risk decision making by carrying out two experimental studies. The studies make full use of fMRI that possesses a high spatial resolution and the ERP with a high temporal resolution to explore the neural characteristics of the three stages of risk decision making—anticipation, decision making and outcome evaluation. This study found that the anticipation affect plays a key role in all three stages:anticipation, the decision choice and outcome evaluation. But the role it plays is not the same across the three stages and the processing procedures of these three stages per se are different from each other.The studies were carried out on the basis of the recent advance of decision science, cognitive science, neuroscience and etc. to intensively investigate the principle of the risk decision making according to the fMRI's spatial data, ERP's temporal information as well as the behavioral results.It draws the conclusion as follows:(1) At the stage of anticipation, the anticipatory affect exsits. With the method of functional magnetic resonance imaging, we observed that both gain and loss cues could induce the activation of reward-related regions including ventral, dorsal striatum and midbrain as well as the punishment-related areas insula at the same time. The signal of both reward and punishment areas increase with the raise of the cue levels. Such an activation mode indicate the complicated anticipatory affect consists of both the hope for large gain (small loss) and fear of small gain (large loss), reflecting the motivation of the decision maker.(2) At the stage of outcome evaluation, the brain is sensitive to the valence of the outcome. The positive and negative results have a discrepant activation, the medial prefrontal cortex and ventral striatum represent the win outcome, while the insula and cingulate cortex represent the loss results, different from the similar activation mode toward both gain and loss cues at the stage of anticipation. In addition, both the ventral and dorsal parts of the striatum is engaged in the process of the hope for possible gain in the stage of anticipation, but only the ventral striatum is involved in the positive outcome evaluation in representing the reward prediction error, further supporting the distinct processing of the anticipation and outcome evaluation.(3) Similar with the exsitence of the anticipatory affect at the stage of the anticipation, the decision affect exist at the decision stage, which helps the decision makers coordinate the affect to finish the decision making rapidly and effectively. With the adoption of the event-related potential, we observed both the ERN and Pe are involved in the modulation of the risky situation and investment choice. The ERN reflects the ancipatory affect evaluation that derives from the tradeoff the possible risk and reward in near future, and the subsequent Pe indicate the goodness or badness of the choice option. The ancipatory affect for the future that the ERN which orgined from anterior cingulate cortex conveys made the subject do the adaptive decisions. Additionally, such a processing is accomplished at the sysem 1 subconsciously from the perspective of the dual system hypothesis.(4) At the stage of outcome evaluation, the outome results reflect the re-evaluation of the decision anticipation, which makes a preparation for the learning and behavioral adjustment for the next round of decision making. Different from the processing that happened at the stage of decision making, although same as the ERN that is also orgined from ACC, the FRN is not engaged in the modulation of the risky situation,instead it's sensitive to the probability of choice at the stage of decision making. The larger the probability of the choice at the stage of decision making, the more obvious the FRN is at the stage of outcome evaluation, which represents the discrepancy between the decision anticipation at the stage of decision and the revealed results at the outcome stage. Again, the FRN represent the reward prediction error, consistent with the conclusion draw from the fMRI's ventral striatum activation at the outcome evaluation stage. The innovation points of this study are as follows:(1) In this study, we observe the existence of the anticipatory affect which reflects the motivaition toward the possible outcome in future. This study validates the basic conclusion of Knutson & Greer's anticipatory affect hypothesis with the fMRI technique. This study observe that both the reward and punishment-related system simultaneously involved in the processing of the gain and loss cues and such an engagement is sensitive to the arousal of the cues. This activation mode reflects the anticipatory affect for the fear and hope for the uncertain outcome and further embodys the decision motivation of the anticipation stage. Such a conclusion further extends the recent reports that the activation of the reward related system such as the necleus accumbens could predict the risk taking behavior while the activation of the punishement related system such as insula could predict the loss aversion behavior.(2) In this study, we observe the neural processing at the decision stage reflect the decision makers' adaptive choice. This study observe the ERN is involved in the dynamic processing of the risky decision situation and the risky investment choices, which reflects the ancipatory evaluation of the tradeoff of risk and reward, guiding the decision maker make the optimal choice in the dynamic risky settings. The guidance of the ERN that origned from the anterior cingulate cortex indicates that the affect play a key role at the efficient decision making of the individual decision maker, which gives a direct support for Damasio's somatic marker hypothesis and dual system model that Kahneman summarized in behavioral decision making from the neuroscience level. So from the perspective of the dual system model of the brain, the study suggests that the system 1 is quite important in the quick and accurate decision makings.(3) The ancipatory affect plays an important role at all the three stage of decision making:ancipation, decision selection and outcome evaluation stage. As mentiond in the first innovation point, ancipatory affect play a vital part at the anticipation stage, reflecting the anticipation motivation toward future reward and punishment outcome. At the decision selection stage, the anterior cingulate cortex worked as an important part to coordinate the emotion to represent the anticipated risk and reward through ERN. At the outcome evaluation stage, anterior cingulate cortex represents the anticipatory violation through the FRN. Therefore, the ancipatory affect involves in all three stage of decision making. The anticipatory affect not only play a role at the stage of the anticipation, but also at the stage of decision making and outcome evaluation, further enrich the content of the anticipatory affect hypothesis put forward by the decision neuroscientists.(4) The processing of anticipation, decision making and outcome evaluation are different, not only the anticipated and experienced utility are dissociated, but also the decision and experienced one. First, at the stage of the anticipation, the gain and loss anticipation activate both the reward and punishment-related systems at the same time reflect the decision motivation. At the stage of outcome evaluation, the positive and negative outcome has respective activation; the former has the reward related regions engaged, while the later has the punishment related regions involved. Therefore, the anticipated and experienced utilities are not the same. The decision stage is mainly represented by the activation of the ACC to reconcile the reward and risk tradeoff, suggesting the adaptive representation of the decision making. The outcome evaluation stage is also represented by the ACC orgined component, FRN. But different from the ERN that is sensitive to the risky situation, the FRN is not sensitive to the risky situation, but merely response to the anticipation violation. Therefore, decision and experienced utilities are distributed. In general, from the spatial and temporal levels of neuroscience, this study validates the difference of the utility at different stage of decision that was initially put forward by Kahneman & Wakker.