LOS ANGELES (AP) - A new study suggests the proliferation of gay and transgender characters in films and television shows has not prevented gay, lesbian, bisexual and transgender actors from experiencing discrimination in Hollywood. The Screen Actors Guild-American Federation of Television and Radio Artists commissioned the survey, released Friday. It found that more than half of the actors who identify as gay, bisexual and transgender think directors and producers are biased against them. More than one-third of the actors who don't fall into those categories agreed with that perception. Only 16 percent of the gay, bisexual and transgender respondents, however, said they had experienced discrimination. Gay men reported the most, with about one-fifth saying they had been discriminated against. The online survey of nearly 5,700 SAG/AFTRA members also found that more than half of the gay, transgender and bisexual respondents had heard producers and directors make anti-gay comments while working on-set. The performers' union, which is holding its annual convention in Los Angeles, said it pursued the first-of-its-kind research at the request of a committee that represents lesbian, gay, bisexual and transgender members and as a methodical way to explore an issue usually discussed through anecdotes. The study was conducted by the Williams Institute, a think tank based at UCLA that specializes in sexual orientation, gender identity and public policy. "The survey results show both progress and indications that more work will be necessary to make the workplace an equal and fully welcoming place for LGBT performers," M. V. Lee Badgett, a University of Massachusetts, Amherst economics professor affiliated with the UCLA institute. The good news is that almost no one thought that opportunities for LGBT actors were getting worse. Of the 5,692 participants, 465 identified as gay men, 61 as lesbians, and seven as transgender. Another 301 men and women described themselves as bisexual. The survey also revealed that despite concerns about being typecast, two-thirds of the gay actors who had played gay characters felt that it had not harmed their careers or limited the roles they were offered. Nine percent of the gay men and lesbians said they had been turned down for roles during the past five years because of their sexual orientations.