The Effects Of Monetary Reward Processing On Deception And Honesty:A Cognitive Neural Mechanism Study

For the purpose of improving the ecological validity of lying research,the study of spontaneous deception is becoming a hot spot.However,most of previous studies have unilaterally explored the impact of rewards on deception,and did not delve into how reward affects spontaneous deception when honesty is also valuable.In addition,these lying studies only compared the difference between deception and honesty,but rarely explore behavioral motivation.Finally,task-fMRI was usually used to explore the difference between deception and honesty,but the characteristics of both in the resting state are still need to be explored.The purpose of this study is to use fMRI to comprehensively and meticulously develop the effects of reward multiples and scale on deception and honesty,and its cognitive neural mechanism;whether monetary sensitivity that can describe the behavioral motivation and emotional experience of the subjects under the stimulus of money could be used to predict the spontaneous deception;and whether the spontaneous deception has a stable resting state functional network characteristics.This thesis is divided into two studies.The study 1 explores the impact of reward on deception and the relationship between monetary sensitivity and deception through a combination of point detection tasks(Experiment 1)that could stimulate the spontaneous deception of the participants and money stimulation delay task(Experiment 2)that could reflect the monetary sensitivity.In Experiment 1,we set reward size contrast,compare the difference between deception and more profitable honesty(relatively honest),deception and less profitable honesty(absolute honesty),and we also manipulating different reward size(0.1 and 1 yuan)and different bonus multiples(2x and 5x).It was found that the larger magnitude of 1 yuan can cause more deception,and there is a significant difference in activation of honesty and deception in the left precuneus.In the smaller order(0.1 yuan),the right superior frontal cortex is more active in the deception.These results show that the manipulation of the reward size can separate the psychological operation process of deception and honesty.Under the multiple conditions,there is no significant difference between the deception numbers under the conditions of 2x and 5x.Under the condition of 5x,there is a significant activation difference in the postcentral cortex and insula,which showed that reward regulated deception and honesty through the emotional processes.Under the condition of 2x,it can still be found significant activation difference of insula between honesty and deception.In addition,the activation of putamen is higher under this condition,indicating that the multiple condition can cause more intense emotion experience.Regardless of how the reward size or multiple changes,honesty can always lead to a more intense reward experience.Experiment 2 tried to predict the behavior of the participants from the perspective of motivation and emotional experience under the influence of money.We extracted the percentage change of BOLD(blood oxygen level-dependent)signal under different rewards in the nucleus accumbens(NACC),and calculated its correlation with deception numbers.We found that participants responded longer with greater reward,and the percentage change of NACC in the negative reward condition could predict the subjects' deception better.On the basis of Study 1,the study 2 used the graph theory method to explore whether there is a difference in the topological properties of the resting state functional network between the deception and honest group.We found there was no significant differences in the global attributes of the functional network.But compared with the honest group,the deception group had a decreased betweenness centrality in the left pars triangularis and left orbit frontal cortex,and increased betweenness centrality in the right insula.These results showed that although deception or honesty may not be related much to the global properties of the brain's functional network,local changes in some nodes in the network may be key factors influencing deception and honesty.In conclusion,this paper explores the role of value factors in lying using an experimental paradigm that allows better manipulation of reward information,and analyzes the effects of different value factors on lying from the perspective of imaging.In addition,by comparing the differences of network attributes between the lying and the honest groups in the resting state,the important role of the brain region of the prefrontal lobe in the psychological process of lying was further clarified.