title: Diffusion of responsibility attenuates altruistic punishment: A functional magnetic resonance imaging effective connectivity study.
abstract: Humans altruistically punish violators of social norms to enforce cooperation and pro-social behaviors. However, such altruistic behaviors diminish when others are present, due to a diffusion of responsibility. We investigated the neural signatures underlying the modulations of diffusion of responsibility on altruistic punishment, conjoining a third-party punishment task with event-related functional magnetic resonance imaging and multivariate Granger causality mapping. In our study, participants acted as impartial third-party decision-makers and decided how to punish norm violations under two different social contexts: alone (i.e., full responsibility) or in the presence of putative other third-party decision makers (i.e., diffused responsibility). Our behavioral results demonstrated that the diffusion of responsibility served as a mediator of context-dependent punishment. In the presence of putative others, participants who felt less responsible also punished less severely in response to norm violations. Our neural results revealed that underlying this behavioral effect was a network of interconnected brain regions. For unfair relative to fair splits, the presence of others led to attenuated responses in brain regions implicated in signaling norm violations (e.g., AI) and to increased responses in brain regions implicated in calculating values of norm violations (e.g., vmPFC, precuneus) and mentalizing about others (dmPFC). The dmPFC acted as the driver of the punishment network, modulating target regions, such as AI, vmPFC, and precuneus, to adjust altruistic punishment behavior. Our results uncovered the neural basis of the influence of diffusion of responsibility on altruistic punishment and highlighted the role of the mentalizing network in this important phenomenon. Hum Brain Mapp 37:663-677, 2016. © 2015 Wiley Periodicals, Inc.
authors.affiliation: Institute of Affective and Social Neuroscience, School of Psychology and Sociology, Shenzhen University, Shenzhen, China.|State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China.
authors.forename: Chunliang
authors.initials: C
authors.lastname: Feng
authors.affiliation: Department of Electrical and Computer Engineering, Auburn University MRI Research Center, Auburn University, Auburn, Alabama.|Department of Psychology, Auburn University, Auburn, Alabama.|labama Advanced Imaging Consortium, Auburn University and University of Alabama Birmingham, Alabama.
authors.forename: Gopikrishna
authors.initials: G
authors.lastname: Deshpande
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Liu
authors.affiliation: Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Ruolei
authors.initials: R
authors.lastname: Gu
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University, Beijing, China.|Collaborative Innovation Center of Sichuan for Elder Care and Health, Chengdu Medical College, Chengdu, China.
authors.forename: Yue-Jia
authors.initials: YJ
authors.lastname: Luo
authors.affiliation: Molecular Neuroscience Department, George Mason University, Fairfax, Virginia.|Department of Psychology, George Mason University, Fairfax, Virginia.
authors.forename: Frank
authors.initials: F
authors.lastname: Krueger
mesh_terms: D000533:Altruism; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003657:Decision Making / Q000502:physiology*; D005260:Female; D005717:Games, Experimental; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D015999:Multivariate Analysis; D009434:Neural Pathways / Q000502:physiology; D009483:Neuropsychological Tests; D011678:Punishment / Q000523:psychology*; D055815:Young Adult
keywords: Granger Causality mapping; altruistic punishment; diffusion of responsibility; functional magnetic resonance imaging (fMRI); mentalizing