Anti-gay attitudes and behaviors (sometimes called "homophobia" or "heterosexism") have been objects of psychological research. Such research usually focuses on attitudes hostile to gay men, rather than attitudes hostile to lesbians. Anti-gay attitudes are often found in those who do not know gay people on a personal basis. There is also a high risk for anti-gay bias in psychotherapy with lesbian, gay, and bisexual clients. One study found that nearly half of its sample had been the victim of verbal or physical violence because of their sexual orientation, usually committed by men. Such victimization is related to higher levels of depression, anxiety, anger, and symptoms of post-traumatic stress. Through the 2015 U.S Transgender Survey, which was conducted by the National Center for Transgender Equality, transgender people of color were found to face disproportionate discrimination because of their overlapping identities. These forms of discrimination included violence, unreasonable unemployment, unfair policing, and unfair medical treatment.