A new study by a team of psychology researchers shows that adolescent boys may also respond aggressively when they believe their masculinity is under threat -- especially boys growing up in environments with rigid, stereotypical gender norms. "We know that not all men respond aggressively to manhood threats -- in past work, we have found that it is primarily men whose stereotypical masculinity is socially pressured who are the most aggressive under such threats," says Adam Stanaland, a postdoctoral researcher at New York University and the paper's lead author.