In Japan, a lot of people used to be prejudiced against gay men, lesbians or bisexuals despite the fact that “homosexuality” as a category was eliminated from diagnostic criteria. Still, there is little investigation into the relations between individual's personality and the attitudes toward homosexuals.

A total of 164 heterosexual students of health and welfare (91 men and 67 women) with a mean age of 19.7 (SD = 1.0) years participated in the questionnaire survey. They were asked to complete the Index of Attitudes toward Homosexuals (IAH) and a short form of Five Factor Personality Questionnaire as well as an inquiry about their encounters with homosexuals.

Factor analysis of IAH resulted in three-factor solutions with factors identified as “avoidance of homosexual neighbors”, “avoidance of contacts with homosexuals” and “avoidance of approach from homosexuals”. Logistic regression analysis showed that “encounters with homosexuals” (=yes, OR = .15, 95%CI: .05–.46) and personality traits such as “extroversion” (OR = 1.12, 95%CI: 1.05–1.19), “emotionality” (OR = 1.14, 95%CI: 1.07–1.21) and “playfulness” (OR = .85, 95%CI: .79–.93) were predictors of “avoidance of homosexual neighbors”. Similarly, “avoidance of contacts with homosexuals” was associated with sex (=male, OR = 2.73, 95%CI: 1.38–5.42), “extroversion” (OR = 1.05, 95%CI: 1.00–1.11) and “playfulness” (OR = .92, 95%CI: .86–.98), and “avoidance of approach from homosexuals” was associated with sex (=male, OR = 6.90, 95%CI: 3.25–14.64), “emotionality” (OR = 1.08, 95%CI: 1.02–1.14) and “playfulness” (OR = .92, 95%CI: .86–.99). These results indicate that personality traits weakly but significantly influence the development of attitude toward homosexuals among Japanese adolescents.