title: Honesty mediates the relationship between serotonin and reaction to unfairness.
abstract: How does one deal with unfair behaviors? This subject has long been investigated by various disciplines including philosophy, psychology, economics, and biology. However, our reactions to unfairness differ from one individual to another. Experimental economics studies using the ultimatum game (UG), in which players must decide whether to accept or reject fair or unfair offers, have also shown that there are substantial individual differences in reaction to unfairness. However, little is known about psychological as well as neurobiological mechanisms of this observation. We combined a molecular imaging technique, an economics game, and a personality inventory to elucidate the neurobiological mechanism of heterogeneous reactions to unfairness. Contrary to the common belief that aggressive personalities (impulsivity or hostility) are related to the high rejection rate of unfair offers in UG, we found that individuals with apparently peaceful personalities (straightforwardness and trust) rejected more often and were engaged in personally costly forms of retaliation. Furthermore, individuals with a low level of serotonin transporters in the dorsal raphe nucleus (DRN) are honest and trustful, and thus cannot tolerate unfairness, being candid in expressing their frustrations. In other words, higher central serotonin transmission might allow us to behave adroitly and opportunistically, being good at playing games while pursuing self-interest. We provide unique neurobiological evidence to account for individual differences of reaction to unfairness.
authors.affiliation: Department of Psychiatry, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan. hidehiko@kuhp.kyoto-u.ac.jp
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Takahashi
authors.forename: Harumasa
authors.initials: H
authors.lastname: Takano
authors.forename: Colin F
authors.initials: CF
authors.lastname: Camerer
authors.forename: Takashi
authors.initials: T
authors.lastname: Ideno
authors.forename: Shigetaka
authors.initials: S
authors.lastname: Okubo
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsui
authors.forename: Yuki
authors.initials: Y
authors.lastname: Tamari
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Takemura
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Arakawa
authors.forename: Fumitoshi
authors.initials: F
authors.lastname: Kodaka
authors.forename: Makiko
authors.initials: M
authors.lastname: Yamada
authors.forename: Yoko
authors.initials: Y
authors.lastname: Eguchi
authors.forename: Toshiya
authors.initials: T
authors.lastname: Murai
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Okubo
authors.forename: Motoichiro
authors.initials: M
authors.lastname: Kato
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ito
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Suhara
mesh_terms: D006801:Humans; D008297:Male; D017008:Negotiating; D049268:Positron-Emission Tomography; D011985:Receptors, Serotonin / Q000378:metabolism; D012059:Rejection, Psychology; D012701:Serotonin / Q000378:metabolism*; D012919:Social Behavior; D055815:Young Adult
chemical_list: D011985:Receptors, Serotonin; D012701:Serotonin