Same-sex and opposite-sex best friend interactions among high school juniors and seniors.

Eighteen adolescents were videotaped during same-sex and opposite-sex interactions in the eleventh and twelfth grades. In both grades, females felt more comfortable during same-sex interactions than during opposite-sex interactions, and they rated their same-sex partners more positively than did males. Females in both grades and males in eleventh grade showed more peer intimacy than did males in twelfth grade. Eleventh-grade females showed the most playful behaviors (the most engaged state). More synchrony (matching of behavior) was found for the animated state in the twelfth grade as compared with the eleventh grade.