Ishii, K.（石井敬子）, Kim, H. S., Joni Y. Sasaki, J. S., Shinada, M. （品田瑞穂）, & Kusumi, I. (2014). Culture modulates sensitivity to the disappearance of facial expressions associated with serotonin transporter polymorphism (5-HTTLPR) Culture and Brain, March 2014 doi: 10.1007/s40167-014-0014-8
The present research investigated an association between the serotonin transporter polymorphism (5-HTTLPR) and sensitivity to the disappearance of facial expressions cross-culturally and found, for the first time, that cultural norms and practices modulate the association. Participants watched both happy-to-neutral and sad-to-neutral movies and judged the point at which the emotional expressions disappeared. As predicted, the results showed that Japanese with the s/s genotype detected the disappearance of facial expressions (particularly the disappearance of smiles) with greater perceptual efficiency than did those with s/l and l/l genotypes, whereas such a tendency was not found in Americans. This suggests that people with the s/s genotype of 5-HTTLPR are more sensitive to environmental changes, but only when the change is culturally important, compared to people with the long allele. Moreover, Asian Americans’ pattern was much more similar to European Americans than to Japanese, supporting the idea that the differences between cultural groups are indeed due to different cultural experiences.