Doctoral student Jessica Remedios of the University of Toronto had 22 women and nine men view 104 photos of straight and gay black and white males and rated their likeability on a scale of 1-7 -- with 1 as not likable and 7 extremely likable.
Participants were not informed that some of the men pictured were gay.
"We observed that people judge others based on sexual orientation even if they are not consciously aware of whether someone is gay or straight," Remedios said in a statement.
In a second study, 36 women and 14 men were divided into groups to view the same 104 photos. One group was instructed to approach whites and avoid blacks, by pulling a joystick toward them when a white face appears and pushing the joystick away when a black face appeared -- while the other group was instructed vice versa, to approach blacks and avoid whites.
The responses were faster for the straight men than for the gay ones, but among participants approaching blacks, responses were faster for gay than straight men.
"These findings suggest that sexual orientation, despite lacking explicit perceptual markers, infiltrates the automatic impression that is formed," Remedios said. "Further, our judgment of gay men depends on whether they are white or black."
The findings were Journal of Experimental Social Psychology.