(CN) – State legalization of same-sex marriage has significantly reduced homophobia across the United States, though federal action may have led to national polarization on attitudes toward lesbian and gay people, according to a new study released Monday.
The findings – published in the Proceedings of the National Academy of Sciences of the United States of America – provide evidence public policy can shape social norms and alter the attitudes of people, according to senior author, Eric Hehman, a psychology professor McGill University in Montreal, Canada.
“The idea that norms shape attitudes has been around in social psychology for many years,” Hehman said in a statement.
“We wanted to measure if laws and policies can also act as norms and potentially change deeply rooted biases,” he added.
Massachusetts was the first U.S. state to legalize same-sex marriage in 2004. Thirty-four other states and the District of Columbia followed suit before same-sex marriage became legal under federal law in June 2015, following the U.S. Supreme Court decision in Obergefell v. Hodges.
The study was conducted over 12 years and gathered about 1 million responses using the website Project Implicit, launched in 2002 to measure biases of respondents. Researchers tested whether state-by-state legalization of same-sex marriage was associated with regional decreases in antigay implicit and explicit bias.
Researchers compared trends before and after state-level legalization of gay marriage in each state.
The study found the local legislation reduced antigay bias, even though biases against lesbian and gay people were already decreasing. States which legalized same-sex marriage experienced decreases in homophobia at a sharper rate – declining at roughly double the previous rate – after legalization, according to the study.
For the 15 states that didn’t pass laws legalizing same-sex marriage before it became federal law, Hehman and his research team found a “backlash effect” where homophobia increased in those states in the immediate aftermath after the Supreme Court ruling – despite a decreasing trend in anti-gay bias prior to Obergefell.
While the data gathered by the researchers cannot show the “specific factors driving this effect,” the researchers postured “a tipping point of local support had not yet been reached for the majority to accept the federal ruling” despite a softening of antigay bias before Obergefell.
“Research at the individual level suggests that the attention given the federal decision may have sharpened some respondents’ sense of symbolic threat to their lifestyle and values, and this sense of threat could have exacerbated antigay biases among those individuals,” the study says.
But the dearth between states with increasing positive attitudes toward lesbian and gay people and those with increasingly negative attitudes toward homosexual people – especially after federal legislation of gay marriage – highlights the importance of the locality of social norms, according to researchers.
“Should legislation be perceived as imposed upon the local culture, a backlash effect might be expected … provid[ing] tentative evidence that more localized policies may be more strongly associated with attitude change, perhaps because the norm is perceived as stronger and arising from a more local population,” the study states.
According to the study, the results “indicate that attitudes and legislation may be mutually reinforcing” where improving attitudes regarding gay people in all states prior to legalization “may have served as impetus and momentum for both state and federal legislation.”
“These enacted legislations in turn strengthened and consolidated favorable attitudes toward lesbians and gay men,” according to the study.
The study found identical effects among both implicit and explicit measures of bias, an important finding according to the researchers.
“That a similar pattern is evident among implicit measures, which are less susceptible to conscious control and social desirability, is important evidence supporting that government legislation is associated with true changes in the attitudes of its citizens,” according to the study.
Researchers Eugene Ofosu, Michelle Chambers and Jacqueline Chen also contributed to the study.