The Effect Of Effort On The Dynamic Temporal Processing Of Prosocial And Pro-self Rewards: An Event-related Potential Stud

Reward processing is essential for human survival and development.The question of how reward processing is affected by the effort,whether the effort is perceived as a cost(reducing the subjective value of a reward)or a reward(increasing the subjective value of a reward),is called the "paradox of effort." As people pay more and more attention to the role of effort in motivation,cognitive control,and value-based decisionmaking,exploring the "effort paradox" will promote the formation of a unified theory and provide clues on enabling sustained effort.Although predecessors have preliminarily studied the neural mechanism of reward processing,some problems still need to be further explored.First of all,previous studies mainly focused on the single stage of reward processing and lack of efforts to decompose the different stages of reward processing in more detail.Secondly,previous studies have explored the impact of efforts on pro-self reward processing but ignored the relationship between efforts and prosocial rewards,and also need to work in pursuit of prosocial rewards,such as COVID-19’s ongoing efforts in epidemic prevention and control,medical treatment frontline staff and medical personnel.Finally,the time dynamic process of prosocial and pro-self reward processing is unclear.Through two experiments,using the adapted effort-door task,this study will strive to quantify the prosocial and pro-self reward processing process at the cognitive behavior and neurophysiology level and explore the dynamic changes of the time course of the two kinds of reward processing.In this study,pro-self reward operation is defined as winning money reward for themselves,and prosocial reward operation is described as winning money reward for charities.The time dynamic change operation of reward processing is defined as the increase or decrease of behavioral and neural indexes of reward expectation and result evaluation with the rise of trials.Experiment 1 explored the effect of effort on prosocial and pro-self reward processing habituation from cognitive behavior.A total of 44 subjects completed the adaptation effort-door task.By obtaining the scores of subjects’ desire for reward and happiness,this paper explores the dynamic impact of high and low effort on the time course of prosocial and pro-self reward in reward-anticipation and reward-outcome.The results showed that: in the reward-anticipation stage,the craving score of high effort was higher than that of low effort;In the reward-outcome stage,in the prosocial reward condition,there was no difference between the happiness score of high and low effort with the increase of trials,while in the personal reward condition,compared with the high effort,the happiness score of low effort decreased with the rise of trials.Experiment 2 explored the effect of effort on prosocial and pro-self reward processing habituation from the neurophysiological level.A total of 42 subjects completed the adapted effort-door task and collected their EEG data simultaneously.Through the relevant EEG indexes(effort-N2,effort-P3,Rew P,fb-P3),the subjects explored the time course dynamic impact of high and low effort on prosocial and proself reward in reward-anticipation and reward-outcome.The results showed that high effort induced a higher amplitude of effort-N2 and effort-P3 than low effort in the reward-anticipation stage.In the reward-outcome stage,under the condition of prosocial reward,there was no difference in the amplitude of Rew P induced by high and low effort with the increase of trials.In the pro-self reward condition,the Rew P amplitude induced by the low effort decreased with the rise in trials compared with the high effort.Under prosocial and pro-self reward conditions,there was no difference in fb-P3 amplitude induced by high and low effort with the increase of trials.Based on these results,the following conclusions can be drawn:1.Under the condition of prosocial reward,the motivation level of high effort is enhanced compared with low effort.Still,the happy experience is not affected by the degree of effort.Under the condition of pro-self reward,the motivation level and happy experience of high effort are enhanced compared with low effort.It has been verified from cognitive behavior and neurophysiology,which supports the theories of "effort valuation." 2.Under the condition of per-self reward,compared with low effort,the happy experience caused by high effort increases with the increase of trials,which confirms the "State-dependent valuation" model from cognitive behavior and neurophysiology aspects.