Abstract:

Social exclusion exists widely, is a phenomenon that is ostracized or rejected by a group or an individual. It not only impairs people's needs of belonging and relationship but also has a negative impact on human cognition, affection, and behavior. For example, previous studies found that social exclusion could impair the cognitive function because people need to use their self-control resources to regulate the negative emotions resulting from social exclusion. Therefore, it is hard for excluded people to make rational judgments in decision-making which requires more cognitive resources. There were also empirical studies indicating that people tended to risk-seeking in risk decision-making tasks after been excluded. Intertemporal decision-making is a particular type of decision-making. It requires people to choose between the options occurring at different points of time, especially between present and future options. Though there was a high similarity between intertemporal decision-making and risk decision-making in theoretical development and neural basis, whether and how social exclusion affects intertemporal decision-making is largely unknown. Hence, the present study aimed to explore the effect of social exclusion on intertemporal decision-making and its potential mechanism.

From the perspective of the process, intertemporal decision-making could be divided into evaluation and selection stages. This research concluded that there are two mechanisms of social exclusion affect intertemporal decision-making which respectively in the evaluation and selection stages. And this research concluded two mechanisms of social exclusion that affect intertemporal decision-making, respectively, in these two stages. Thus, we constructed a two-stage model to explain how social exclusion affects intertemporal decision-making. Intertemporal decision-making is closely related to the time of delay. Previous studies revealed that social exclusion would impair the time perception of the excluded people. Considering the importance of time perception for intertemporal decision-making, it would be with a great possibility that social exclusion would lengthen the excludeds’ time perception at the valuation stage, therefore reduce their subjective value of the delay option. Then the excluded people had to regulate their negative emotions by consuming self-control resources at the selection stage. While the reduction of self-control resources may weaken the control capability and make excluded people unable to resist the urge for immediate options, consequently, result in the high discount rate of intertemporal decision-making.

We tried to buffer the negative effect of social exclusion and improve the intertemporal decision-making capability of the excluded people. Based on the two-stage model, time perception and self-control could mediate the effect between social exclusion and intertemporal decision-making. So, the key point is to recover the time perception and self-control resource damaged by social exclusion. Some studies indicated that the right ventrolateral prefrontal cortex (rvlPFC) was a crucial brain region that can regulate a range of negative effects of social exclusion, the activation of rvlPFC would significantly reduce the negative emotion and aggressive behavior in the social exclusion. Therefore, transcranial direct current stimulation (tDCS, a non-invasive brain stimulation technology) would be used to activate the rvlPFC of the excluded people. We assumed that the activation of rvlPFC would normalize their time perception and recover their self-control resource. Moreover, social exclusion is a dynamic situation, the effect of the short-term exclusion has highly possible be different from the long-term exclusion. So, this research would also distinguish the short-term and long-term exclusion and give them the respective study.

The results of this research would reveal how interpersonal factors affect the intertemporal choice and how to improve the excludeds' ability of intertemporal decision-making. The findings would have implications in helping the excluded people make rational decisions in life, such as health, education, marriage, savings, and improve their quality of life and personal achievement.

Key words: intertemporal decision-making, social exclusion, time perception, self-control