Researchers know that guys tend to find women in red to be alluring; now, they're investigating how women react to the color. Research headed by a University of Rochester psychologist finds that women see others wearing red "as if these other women are actively advertising" sexual availability. For instance, "there is a huge reluctance to introduce or let a boyfriend spend time alone (with a woman wearing red)," Adam Pazda tells LiveScience. "You see this defensive behavior intention, like, 'I don't want my boyfriend anywhere near this girl.'"
His team referred to studies across two continents. In one, half of the women participating saw an image of a woman in red; the other half saw the same picture—except the woman was wearing white. Their responses supported statements like "this person is interested in sex," the Pacific Standard reports. Another study saw subjects viewing photos of a woman in a red or green shirt. Asked how likely they'd be "to introduce this person to your boyfriend," women "reported stronger intentions to guard their mate from the target" when she was wearing red. Pazda emphasizes that his results refer to "tendencies" and aren't always applicable. An earlier study points to a link between red and fertility.