The Neurocomputational Mechanism Underlying Decision-Making on Unfairness to Self and Others

Neural computational mechanisms underlying fairness-based decisions: Self-Unfairness and Other-Unfairness

Abstract: Fairness is a fundamental value in human society, and individuals show concern for both self-unfairness and other-unfairness. However, there has been a long-standing debate on whether self-unfairness and other-unfairness evoke shared or distinct neuropsychological processes. To address this issue, we combined a Three-Person Ultimatum Game, computational modeling, and advanced brain imaging analysis techniques to uncover the behavioral, cognitive, and neural patterns of self-unfairness and other-unfairness. Our behavioral and computational results reveal that participants show a higher level of concern for self-unfairness compared to other-unfairness. Furthermore, self-unfairness consistently activated brain regions such as the Anterior Insula, Dorsal Anterior Cingulate Cortex, and Dorsolateral Prefrontal Cortex, which play important roles in processing emotional and cognitive processes related to fairness-based decisions. In contrast, other-unfairness mainly activated areas such as the Middle Occipital Gyrus. In summary, our findings strongly support the existence of distinct neural computational signatures between self-unfairness and other-unfairness.

Background knowledge about this study indicates that while people show concern for unfairness experienced by both themselves and others, there is no consensus on whether these two forms of unfairness are based on the same or different neurocognitive mechanisms. This study was conducted by Lanxin Luo, Han Xu, Xia Tian, Yue Zhao, and others from institutions including the Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences. The research results were published in Neuroscience Bulletin (Neurosci. Bull.).

The research process details how participants handled decision-making scenarios involving elements of self-unfairness and other-unfairness in a Three-Person Ultimatum Game. The analysis methods involved statistical analysis of behavioral data, establishment and validation of computational models, and analysis of neural activity patterns at multiple levels, aiming to explore participants’ response patterns to unfairness and their underlying neural basis from different dimensions.

The main findings of this study are: Individuals show higher sensitivity to self-unfairness compared to other-unfairness, as evidenced by behavioral results, computational model parameters, and differences in brain activity; particularly when processing self-unfairness, the activation intensity of the Anterior Insula, Dorsal Anterior Cingulate Cortex, and Dorsolateral Prefrontal Cortex was more significant than in cases of other-unfairness. The activation of these three brain regions suggests that self-unfairness elicits stronger responses at both emotional and cognitive levels.

The research conclusion emphasizes that although individuals respond to both self-unfairness and other-unfairness, there are significant differences in the neural computational mechanisms for processing these two forms of unfairness. This finding further deepens our understanding of the foundations of the concept of fairness in human social interactions and has important implications for future exploration of real-world scenarios involving conflicts of interest and resource allocation among multiple parties.