I’ve just read two books about sex (Sex at Dawn, and Perv), and the same fascinating study, about something called “erotic plasticity,” was mentioned in both.
In 2005 psychologist Meredith Chivers set up an experiment where she showed a variety of sexual videos to heterosexual and homosexual men and women. The videos depicted a wide variety of activities covering various sexual combinations: male/female, male/male, female/female, female alone, and man alone. At the end, just for the hell of it, she threw in one of bonobos mating. The subject’s genitals were wired to measure blood flow (an accurate indicator of arousal) and the subjects also indicated how turned on they felt with a keypad.
Men were consistent—if they were heterosexual the naked women turned them on but the men did not, and if homosexual, vice versa. The bonobos didn’t turn any of the men on. In addition, the men’s reported feelings matched their genital blood flow.
But women responded genitally to everything—even the bonobos! However, they didn’t report being turned on to everything. They only acknowledged arousal about a subset of videos.
This is interesting enough, but there’s more. It would be easy to conclude that this is just a strange human quirk. But another study, done in 2001 with goats and sheep, shows the same erotic plasticity difference between males and females.