Sex difference in mate preference based on physical attractiveness in Japan: No longer present or still present?

Since Buss (1989) initiated research in the field, sex differences in preferences for long-term mates have been extensively studied in evolutionary psychology. Numerous studies have reported robust sex differences such as: 1) a preference for a younger mate is stronger in men than women, 2) a preference for an older mate is stronger in women than men, 3) women value traits associated with resource acquisition, such as economic status and educational attainment, more highly than do men, and 4) men value physical attractiveness more highly than women. However, our replication of Bech-Sørensen & Pollet (2016) did not to show a significant sex difference in the preference for physical attractiveness among a Japanese sample while the other sex differences (age differences and resource acquisition abilities) were significant (Study 1). We designed study 2 to test if the non-significance was an artifact of the item used to measure the preference for physical attractiveness. Study 2 showed that the sex differences were not statistically significant. In addition, the effect of sex was significantly smaller than the pre-determined smallest effect size of interest (SESOI). #Pre-registration of the study can be found at https://psyarxiv.com/acy9z