The Interactive Effects Of Emotional Engagement And Expected Value On Moral Decision-making And The Function Of VMPFC

The dual-process processing model of moral decision-making believes that moral decision-making mainly involves emotional processing and rational reasoning.The emotional processing process is affected by emotional engagement,while the rational reasoning process is related to cognitive processing such as the evaluation of expected value(determined by probability and magnitude).Existing studies have separately confirmed the influence of emotional engagement and expected value on moral decision-making.However,the dual-process model of moral decision-making indicates that emotion processing and rational reasoning are often integrated,but may conflict with each other in some circumstance,which suggests that the emotional engagement and expected value may interact with ethical decision-making.Therefore,the first goal of the study was to investigate the interactive influence of emotional engagement and expected value on moral decision-making.At the level of brain mechanism,neuroimaging studies have found that the ventromedial prefrontal cortex(VMPFC)is significantly activated in the process of people’s moral decision-making,and is related to the emotional processing;while researches on economic decision-making believe that VMPFC is mainly involved in the expected value evaluation.So,the role of VMPFC in the interaction of emotional engagement and expected value in moral decision-making is still unknown.In order to answer this question,the second goal of this research was to investigate the causal relationship between the excitability of the VMPFC and moral decision-making by using transcranial direct current stimulation(tDCS).We tried to explore the role of VMPFC in moral decision-making under different emotional engagement,probability and magnitude levels.This research included two experiments: Experiment 1 used moral dilemmas under high and low emotional engagement conditions with different probabilities and magnitudes to examine the interactive effects of emotional engagement and expected value on moral decision-making;Experiment 2 investigated the causal relationship of VMPFC in moral decision-making under different conditions by using transcranial direct current stimulation to inhibit the excitability of VMPFC.The results of this study found that:(1)Emotional engagement affected moral decision-making.Compared to high emotional engagement,participants showed higher propensity to endorse utilitarian solutions under the low emotional engagement;(2)Probability and magnitude influenced moral decision-making,as the decreasing of probability(the surviving probability of the lives)and the increasing of magnitude(the number of lives),participants showed higher propensity to endorse utilitarian solutions;(3)The interaction of emotional engagement,probability and magnitude was significant.Under the high emotional engagement,when the surviving probability was high(95%),the difference between the propensity to endorse utilitarian solutions of medium(15 people)and large number of lives(40 people)was not significant;under other probabilities of high and low emotional engagement,as the number of lives increased,participants showed higher propensity to endorse utilitarian solutions.There were significant differences in participants’ propensity to endorse utilitarian solutions between small,medium and large number of lives.(4)Transcranial direct current stimulation on VMPFC could influence moral decision-making.When the number of lives was large(40 people),the probability was medium(50%)and the number of lives was medium(15 people),the surviving probability was high(95%),under cathodal tDCS on VMPFC,female participants showed lower propensity to endorse utilitarian solutions in low emotional engagement;when the number of lives was small(2 people),the probability of surviving was medium(50)and low(5%),under cathodal tDCS on VMPFC,female participants showed higher propensity to endorse utilitarian solutions in high emotional engagement.In summary,the results of the study proved that in moral decision-making,emotional engagement and expected value could interactively affect participants’ propensity to endorse utilitarian solutions.VMPFC is a key area in moral decision-making.Depending on the condition,sometimes VMPFC is involved in emotion processing and sometimes it is involved in value judgment.This study is based on the dual-process model of moral decision-making.First of all,at the behavioral level,we systematically revealed the interactive influence of emotional engagement,probability and magnitude on moral decision-making,which provided empirical support and supplement to the dual-process model of moral decision-making.Secondly,as for the brain mechanism,we used tDCS to explore the influence of excitability changes of VMPFC on moral decision-making under different emotional engagement and expected value,which suggested that the function of VMPFC in moral decision-making under different conditions is dynamic.It is helpful for us to understand the brain mechanism of moral decision-making.