The Influence Of Gain And Loss Situations And Experimental Stimuli On Prosocial Behavior Learning ——Based On Reinforcement Learning Model

Helpfulness is a traditional virtue of the Chinese nation.Prosocial behavior often appears in daily life and promotes the harmonious development of society.Reinforcement learning is a basic behavioral mechanism in many species.For humans,however,reinforcement learning occurs not only in behaviors and results that affect themselves,but also in behaviors and results that affect others.Using a reinforcement learning model,we investigated the effects of different stimulus settings and types on prosocial behavior learning.In experiment 1,participants were asked to choose between two symbols to complete the probabilistic reinforcement learning task.Participants were required to learn to obtain monetary reward or avoid monetary loss under three conditions.Using the model parameters,in the first experiment,the study found that individuals can learn to get money reward or avoid money loss for others.The rate of learning was slower when getting a monetary reward for others than when getting a monetary reward for yourself.But there was no significant difference between the rate of learning to avoid financial loss for oneself and the rate of learning to avoid financial loss for others.In the second experiment,we added time as a new stimulus to explore the prosocial behavior of participants under the condition of time loss,and functional magnetic resonance（fMRI）was used to explore the brain regions involved in prosocial behavior learning.We found that individuals value avoiding lost time for themselves more than avoiding lost time for others.Brain regions such as the dorsolateral prefrontal cortext,cerebellum and parahippocampal gyrus were activated when the participants protected themselves from time loss;brain regions such as the bilateral dorsolateral prefrontal cortex and the dorsal anterior cingulate cortex were activated when the participants protected others from time loss.Set the dorsolateral prefrontal cortex as the seed point to explore the functional connections between dorsolateral prefrontal cortex and other brain regions during prosocial behavior learning,and it was found that ventromedial prefrontal cortex and cerebellum had stronger functional connections.Using the same way,we found dorsal anterior cingulate cortex had stronger functional connections with ventromedial prefrontal cortex,superior frontal gyrus and cerebellum.Therefore,on the behavior level,this study found,under different experimental settings of the same stimulus,subjects’ self-related learning and prosocial behavior learning performance will be different.In the loss condition,subjects will pay equal attention to avoiding losses for themselves and others.In addition,stimulus type will make different individual has different pro-social behavior learning performance.fMRI results showed that there were specific brain regions involved in prosocial behavior learning process.