The "arousometer" was a vaginal photoplethysmograph - a clear acrylic tampon-shaped device to measure genital blood flow.
Using a device inserted into women to measure genital blood flow as a gauge of sexual arousal, Diana Fleischman, PhD, an evolutionary psychologist at the UK's University of Portsmouth, investigated 76 heterosexual women aged between 18 and 42 years.
The findings, which also measured the women's self-reported feelings, are published in the online journal PLOS One.
Dr. Fleischman says: "Sex includes increased contact with body odors and fluids which, in other contexts, strongly suggest disease and would elicit disgust.
"Women are more vulnerable to contracting diseases through sex than men and show worse outcomes once infected, so we should expect that women will be especially turned off when they are disgusted."
One group of women in the study were shown disgusting images before watching an erotic film. The second group watched an erotic film and were then shown disgusting images.
The third group were shown frightening images before watching an erotic film. And the fourth watched an erotic film and were then shown frightening images.
Images used to elicit disgust in the women included diseased or injured humans and human corpses, feces and people vomiting. The images designed to elicit fear included violent people, dangerous animals, weapons, heights, tornados and fire.
The erotic films were intended to be sexually appealing specifically to women and were produced and directed by women.
Before the experiments, all the women were asked to insert a vaginal photoplethysmograph - a clear acrylic tampon-shaped device that measures blood flow to the vagina as an indication of sexual arousal. They were also asked to report their own degree of arousal, disgust and fear after their tests.
Women exposed to disgusting images before watching an erotic film were three times less sexually aroused than those who had seen frightening images or those in the control group.
Overcoming disgust to have sex
Dr. Fleischman says: "It makes sense that sexual arousal and disgust would affect one another. Sexual arousal motivates us toward closeness with others and their bodies while disgust motivates us away." He adds:
"Given these competing motivations, every one of our ancestors had to overcome disgust in order to have sexual contact and reproduce."
The researchers found that previous evidence was mixed on the question of whether sexual arousal decreases feeling of disgust in women.
A consistent difference has been found between men and women: men are less sensitive to disgust when it comes to sex.
"Previous studies have found that men and women who are exposed to sexually explicit images report less disgust," Dr. Fleischman explains. "However, our study is the first to measure blood flow to the genitals, which is necessary for sexual arousal, and how it interacts with disgust."
The research found that women who are not very sensitive to feelings of disgust reduce their sensitivity further when sexually aroused.
By contrast, women who are highly disgust-sensitive show greater disgust when they are sexually aroused.
Dr Fleischman says: "When we are deciding whether to have sex, there are trade-offs to consider. On the one hand you must have sex to reproduce, and on the other hand sexual encounters are risky for disease transmission.
"What our results suggest is that the story is more complicated for women and that women differ in how sexual arousal changes their disgust response."