Cross-cultural differences in prefrontal cortex activity in moral judgment: A functional near-infrared spectroscopy (fNIRS) study based on the CNI model.

BACKGROUND: In the past, comparative cultural neurological studies of moral judgments have mainly focused on Eastern and Western groups. We initially examined Japanese and Chinese groups, both East Asian cultures. We utilized a recently proposed polynomial model known as the "consequences, norms, and generalized inaction" (CNI) model to investigate the variations in the overall prefrontal cortex activity between these two groups during moral judgment. METHODS: We employed functional near-infrared spectroscopy (fNIRS) to analyze the prefrontal cortex (PFC) activity within a CNI model of moral judgment among 23 healthy Japanese and 26 healthy Chinese adults. RESULTS AND CONCLUSIONS: Our study revealed significant differences in the PFC activation between Japanese and Chinese individuals in the CNI moral judgment task context. Specifically, during the CNI task, Chinese men exhibited higher right dorsolateral prefrontal cortex (R-DLPFC) activity than Chinese women. In contrast, Japanese women showed greater left dorsolateral prefrontal cortex (L-DLPFC) activity than Japanese men. In an international comparison, R-DLPFC activity was higher in Chinese men than in Japanese men. Conversely, the left ventrolateral prefrontal cortex activity was higher in Japanese men compared to Chinese men. Additionally, among women, the right ventromedial prefrontal cortex activity was higher in Japanese women than in Chinese women. In conclusion, our findings support the perspective of cultural psychology and identify cultural and sex differences in PFC activity between Japanese and Chinese individuals.

Exploring cultural and gender differences in moral judgment: A cross-cultural study based on the CNI model.

Recently, researchers have proposed a polynomial model called the "consequences, norms, generalized inaction" (CNI) model for researching moral judgment. However, it is unclear whether the model can be used to explore cultural differences in moral judgment. In this study, we investigated the applicability of the CNI model of moral judgment to East Asian groups, and subsequently explored cultural and gender differences in moral judgment between East Asian (i.e., Japan, n = 211; China, n = 200) and Western (i.e., USA, n = 201) groups. The CNI model was proposed by Gawronski et al., and it can quantify individuals' sensitivity to moral consequence, sensitivity to moral norms, and their general preference for inaction or action in moral dilemmas. Our results indicate that the CNI model fits well for Japanese and Chinese individuals. Both East Asian women and Western women were significantly more sensitive to moral norms than men in their respective countries. In the international comparison, Westerners were more sensitive to moral norms. The Japanese groups, for both men and women, were most biased towards inaction. Regarding sensitivity towards consequences, no differences were observed in the comparison between Eastern and Western male groups, whereas poor sensitivity was observed among women. By using this new model, this study provides new insights into the differences of cultural and gender in moral judgment. Supplementary Information: The online version contains supplementary material available at 10.1007/s12144-023-04662-6.