Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published April 30, 2014 | Published
Journal Article Open

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


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.

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 (https://creativecommons.org/licenses/by/4.0/). 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.

Attached Files

Published - 6413.full.pdf


Files (929.6 kB)
Name Size Download all
929.6 kB Preview Download

Additional details

August 22, 2023
October 26, 2023