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Social Equality in the Number of Choice Options Is Represented in the Ventromedial Prefrontal Cortex

Aoki, Ryuta and Matsumoto, Madoka and Yomogida, Yukihito and Izuma, Keise and Murayama, Kou and Sugiura, Ayaka and Camerer, Colin F. and Adolphs, Ralph and Matsumoto, Kenji (2014) Social Equality in the Number of Choice Options Is Represented in the Ventromedial Prefrontal Cortex. Journal of Neuroscience, 34 (18). pp. 6413-6421. ISSN 0270-6474. PMCID PMC6608119. doi:10.1523/JNEUROSCI.4427-13.2014.

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A distinct aspect of the sense of fairness in humans is that we care not only about equality in material rewards but also about equality in nonmaterial values. One such value is the opportunity to choose freely among many options, often regarded as a fundamental right to economic freedom. In modern developed societies, equal opportunities in work, living, and lifestyle are enforced by antidiscrimination laws. Despite the widespread endorsement of equal opportunity, no studies have explored how people assign value to it. We used functional magnetic resonance imaging to identify the neural substrates for subjective valuation of equality in choice opportunity. Participants performed a two-person choice task in which the number of choices available was varied across trials independently of choice outcomes. By using this procedure, we manipulated the degree of equality in choice opportunity between players and dissociated it from the value of reward outcomes and their equality. We found that activation in the ventromedial prefrontal cortex (vmPFC) tracked the degree to which the number of options between the two players was equal. In contrast, activation in the ventral striatum tracked the number of options available to participants themselves but not the equality between players. Our results demonstrate that the vmPFC, a key brain region previously implicated in the processing of social values, is also involved in valuation of equality in choice opportunity between individuals. These findings may provide valuable insight into the human ability to value equal opportunity, a characteristic long emphasized in politics, economics, and philosophy.

Item Type:Article
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URLURL TypeDescription DOIArticle CentralArticle
Camerer, Colin F.0000-0003-4049-1871
Adolphs, Ralph0000-0002-8053-9692
Additional Information:© 2014 the authors. Beginning six months after publication the Work will be made freely available to the public on SfN’s website to copy, distribute, or display under a Creative Commons Attribution 4.0 International (CC BY 4.0) license ( Received Oct. 9, 2013; revised March 15, 2014; accepted April 2, 2014. This work was supported by a Grant-in-Aid for the Japan Society for the Promotion of Science Fellows to R. Aoki (no. 249856), Grand-in-Aid for Scientific Research on Innovative areas to K.Matsumoto (no. 24120717), and a Tamagawa University Global Center of Excellence grant from the Ministry of Education, Culture, Sports, Science, and Technology, Japan. We thank Dr Adam Phillips for assistance. The authors declare no competing financial interests. Author contributions: R. Aoki, M.M., Y.Y., K.I., K. Murayama, A.S., C.F.C., R. Adolphs, and K. Matsumoto designed research; R. Aoki, M.M., Y.Y., A.S., and K. Matsumoto performed research; M.M. contributed unpublished reagents/analytic tools; R. Aoki analyzed data; R. Aoki, Y.Y., K.I., K. Murayama, C.F.C., R. Adolphs, and K. Matsumoto wrote the paper.
Funding AgencyGrant Number
Japan Society for the Promotion of Science (JSPS)249856
Japan Society for the Promotion of Science (JSPS)24120717
Tamagawa UniversityUNSPECIFIED
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Subject Keywords:neuroeconomics; reward system; social comparison
Issue or Number:18
PubMed Central ID:PMC6608119
Record Number:CaltechAUTHORS:20140613-154102084
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46270
Deposited By: Tony Diaz
Deposited On:13 Jun 2014 23:05
Last Modified:10 Nov 2021 17:23

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