Does Unfairness Evoke Anger or Disgust? A Quantitative Neurofunctional Dissection Based on 25 Years of Neuroimaging

bioRxiv (Cold Spring Harbor Laboratory)

Abstract

Abstract Over the last decades, the traditional ‘Homo economicus’ model has been increasingly challenged by convergent evidence underscoring the impact of emotions on decision-making. A classic example is the perception of unfairness operationalized in the Ultimatum Game where humans readily sacrifice personal gains to punish those who violate fairness norms. While the emotional mechanism underlying costly punishments has been widely acknowledged, the distinct contributions of moral emotions (anger or disgust) remain debated, partly due to methodological limitations of the conventional experiments. Here, we capitalize on a quantitative neurofunctional dissection approach by combining recent developments in neuroimaging meta-analyses, behavioral-level, network-level, and neurochemical-level decoding and data from 3,266 participants from functional neuroimaging studies to determine the common and distinct neural representations between unfairness and the two moral emotions. Experience of unfairness engaged a widespread bilateral network encompassing insular, cingulate, and frontal regions, with dorsal striatal regions mediating the decision to reject unfair offers. Disgust engaged a defensive-avoidance circuit encompassing amygdalar, occipital, and frontal regions, while anger engaged non-overlapping systems including mid-cingulate, thalamic, and frontal regions. Unfairness and anger or disgust respectively commonly engaged the anterior and mid-insula, while the latter additionally showed common recruitment of ventrolateral prefrontal and orbitofrontal cortices. Multimodal network, behavioral, and serotonergic decoding provided a more granular and convincing dissection of these results. Findings indicate a shared neuroaffective basis underlying the impact of emotions on unfairness-induced punishment behavior and suggest a common brain circuit has been evolutionarily shaped to protect individuals from personal harm and enforce societal norms.

Authors 11

1. Xianyang Gan

   University of Electronic Science and Technology of China

   Affiliation as printed

   University of Electronic Science and Technology of China;

   University of Electronic Science and Technology of China

2. Ran Zhang

   Southwest University

   Affiliation as printed

   Southwest University;

   Southwest University

3. Zihao Zheng

   University of Electronic Science and Technology of China

   Affiliation as printed

   University of Electronic Science and Technology of China;

   University of Electronic Science and Technology of China

4. Benjamin Klugah‐Brown

   University of Electronic Science and Technology of China

   Affiliation as printed

   University of Electronic Science and Technology of China;

   University of Electronic Science and Technology of China

5. Ting Xu

   Southwest University

   Affiliation as printed

   Southwest University;

   Southwest University

6. Nan Qiu

   University of Electronic Science and Technology of China

   Affiliation as printed

   University of Electronic Science and Technology of China;

   University of Electronic Science and Technology of China

7. Keith Maurice Kendrick

   University of Electronic Science and Technology of China

   Affiliation as printed

   University of Electronic Science and Technology of China;

   University of Electronic Science and Technology of China

8. Klaus Mathiak Aachen

   Universitätsklinikum Aachen · RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University Hospital;

   RWTH Aachen University Hospital

9. Justin Tiwald

   University of Hong Kong

   Affiliation as printed

   The University of Hong Kong

10. Dezhong Yao

    University of Electronic Science and Technology of China

    Affiliation as printed

    University of Electronic Science and Technology of China;

    University of Electronic Science and Technology of China

11. Benjamin Becker corresponding

    University of Hong Kong

    Affiliation as printed

    The University of Hong Kong