Overall performance
Mean rejection rates for unfair and fair offers were 78.8 ± 25.1 and 16.9 ± 22.3, respectively. Participants were more likely to reject unfair offers than fair offers (t = 10.4, P < 0.001). Mean of T scores of overall neuroticism and agreeableness scores were 54.1 ± 12.6 and 46.4 ± 15.4, respectively. As we expected, the rejection rate for unfair offers was positively correlated with straightforwardness (R = 0.59, P = 0.006) and trust (R = 0.54, P = 0.015) facets (Fig. S1 A and B), subscales of agreeableness, but not with the overall agreeableness score (R = 0.35, P = 0.13). That is, honest and trustful people are more likely to reject unfair offers. However, importantly, the rejection rate for unfair offers was neither correlated with the overall neuroticism score (R = ?0.15, P = 0.52) nor with subscales such as anger–hostility (R = ?0.20, P = 0.40) and impulsivity (R = 0.21, P = 0.37). The rejection rate for fair offers did not correlate with any personality scales.
Voxel-wise statistical parametric mapping (SPM) (Fig. 1 A and B) analysis revealed significant negative correlation between the rejection rate for unfair offers and the binding potential for nondisplaceable radioligand in tissue (BPND) (15) of [ 11 C]DASB in the midbrain regions including DRN (Fig. 2A). Confirmatory region-of-interest (ROI) analysis revealed identical results (Fig. 2B). The mean BPND of [ 11 C]DASB in the midbrain including DRN was 3.05 ± 0.86. There were no significant correlations between the rejection rate of fair offers and [ 11 C]DASB binding of any of the brain regions, nor were the rejection rates of unfair and fair offers correlated with [ 11 C]WAY100635 binding. SPM and ROI analyses also revealed that straightforwardness (R = ?0.54, P = 0.013) (Fig. S2 A and B) and trust (R = ?0.51, P = 0.022) (Fig. S3 A and B) were negatively correlated with BPND of [ 11 C]DASB in the midbrain regions including DRN. 70, P = 0.04, one tailed) (Fig. 3). The mediation effect of trust approached significance (Sobel test = ?1.47, P = 0.07, one tailed) (Fig. S4). Because straightforwardness and trust were highly correlated (R = 0.58, P = 0.008), we averaged these indices to enhance the robustness of the mediation model. The analysis revealed a more robust mediation effect (Sobel test = ?1.91, P = 0.03, one tailed). We also tested an alternative model in which personality drives 5-HTT in DRN, which then mediates the relationship between personality and rejection to unfair offers. This model showed that 5-HTT in DRN was not a significant mediator of the relationship between personality and rejection to unfair offers in UG (straightforwardness: Sobel test = 1.09, P = 0.14,one tailed and trust: Sobel test = 1.25, P = 0.11, one tailed).
Correlation anywhere between rejection rates off unfair now offers in the UG and you can 5-HTT binding within the DRN. (A) SPM image exhibiting aspects of negative relationship ranging from rejection speed off unfair now offers and you may 5-HTT joining when you look at the DRN. (B) Plots and regression collection of correlation ranging from rejection rate of unjust now offers and you can 5-HTT binding inside DRN (Roentgen = ?0.fifty, P = 0.026). Dashed outlines are 95% trust period borders.
They indicated that straightforwardness is actually a life threatening intermediary of the relationship anywhere between 5-HTT joining in the DRN and getting rejected off unfair now offers inside the UG (Sobel shot = ?step one
Crockett mais aussi al. (10) showed you to serotonin (5-HT) starred a role inside the modulating reaction to unjust now offers within the UG. A lessening central 5-HT top increased getting rejected in order to unfairness. This means, low-level 5-HT causes us to be shorter open minded away from unfairness and more honest from inside the expressing all of our fury. Having fun with an in vivo molecular imaging techniques, positron emission tomography (PET), we personally measured 5-HT transporters (5-HTT) and you can 5-HT1A receptors and investigated its relation to identification and you may a reaction to unfairness. Because the dishonest behaviors are known to enroll attention regions of sayfa cognitive control, including the dorsal lateral prefrontal cortex (DLPFC) (eleven, 12), and 5-HT signal in the prefrontal cortex (PFC) is important to own intellectual manage (thirteen, 14), we hypothesized that lower 5-HT indication from inside the DLPFC and/or dorsal raphe nucleus (DRN), a major way to obtain 5-HT, might possibly be associated with large rejection of unjust also provides during the UG, which the fresh personality trait of honesty perform mediate that it you’ll relationships.