Cognitive neural mechanisms of social comparison: A review

Social comparison refers to the psychological phenomenon in which individuals compare themselves with others in some respects for accurate self-evaluation. It plays an important role in making reasonable decisions, building good interpersonal relationships, forming one's self-concept, and regulating negative emotions. However, comparing with others who are better than oneself may lower one's self-esteem and subjective well-being. Therefore, examining its psychological and neural mechanisms has important theoretical and practical implications. According to the selective accessibility model, social comparison can be divided into three stages: Selection, comparison, and evaluation. In the first stage, individuals choose the objects and fields of comparison, actively search or passively receive comparative information; in the second stage, individuals compare themselves with others based on their own goals and previous experience; in the third stage, individuals evaluate relative self with corresponding emotional and behavioral responses. The comparison stage, which is the second stage, is the most critical, as it directly determines the outcome evaluation. Although researchers have proposed different theoretical models to explain the mechanisms of social comparison, most of them have remained at the behavioral level. In recent years, more and more researchers have begun to explore the neural mechanisms of social comparison using functional magnetic resonance imaging (fMRI) and event-related potential (ERP) techniques. In this article, we reviewed studies on the neural mechanisms of social comparison in the past decades from the perspectives of spatial localization and temporal process. The findings of fMRI studies on spatial characteristics indicate that the brain regions related to social comparison mainly include the dorsal anterior cingulate cortex (dACC), dorsolateral prefrontal cortex (dlPFC), anterior insula (AI), and amygdala, which are associated with upward comparison (with others who are better than oneself), and the ventral striatum (VS) and ventromedial prefrontal cortex (vmPFC), which are associated with downward comparison (with others who are worse than oneself). Further organization of the functions of related brain regions proposes that the reward and pain networks, the mentalizing network, and the empathy network may be involved in different stages of social comparison. The mentalizing network is involved in the "selection", "comparison", and "evaluation" stages; the reward and pain networks are involved in the "comparison" and "evaluation" stages; while the empathy network is only involved in the "evaluation" stage. For temporal characteristics, the findings of ERP studies indicate that P2, feedback-related negativity (FRN), and P300/late positive component (LPC) reflect the early, middle, and late processing stages of comparison outcome evaluation, respectively. Finally, we discuss the limitations of the current social comparison research and propose that it is necessary to further investigate the neural mechanisms of social comparison in more complicated situations, as well as the mechanisms of individual differences and social factors affecting social comparison in the future.