Cover Story

Men and women experience sexual arousal very differently, not only physiologically but psychologically, according to researchers who are studying arousal using an array of new and refined methods.

Those methods are making it possible for researchers to understand the causes of real-world problems, such as sexual dysfunction and high-risk sexual behavior (see pages 54 and 58). But they are also giving researchers the means to explore basic questions about the nature of sexual arousal and how its different components--such as physiological arousal and subjective experience--are related to each other.

"It's easier to get funding for research that focuses on, let's say, AIDS-related sexual behaviors, than for research on the very fundamental question of what sexual motivation and sexual arousal really are," says Erick Janssen, PhD, a psychologist at the Kinsey Institute for Research in Sex, Gender and Reproduction at Indiana University. "But in the long run, those basic questions have to be answered before we can move on to explain other, related behaviors."

Cognition and arousal

One active area of research concerns cognitive factors that influence sexual arousal. In the mid-1980s, Boston University psychologist David Barlow, PhD, and his colleagues conducted a series of studies to examine the relationship between anxiety and sexual arousal. They found that men with and without sexual problems reacted very differently to anxiety-inducing threats of mild electric shock.

Men who reported having no trouble getting and maintaining erections, says Barlow, "would believe that they were going to get shocked if they didn't get aroused, so they would focus on the erotic scene." The result was that the threat of shock actually increased sexual arousal. But men who had sexual problems responded to the threat of shock very differently, says Barlow. "Their attention would be so focused on the negative outcomes that they wouldn't be able to process the erotic cues," he explains.

Since those initial studies, Barlow and his collaborators have been trying to tease apart the factors that distinguish men with and without sexual problems. One of the key differences, he says, is that men with sexual arousal problems tend to be less aware of how aroused they are.

Another difference has to do with how men react to instances when they can't become aroused, says Barlow. "Males who are able to get aroused fairly easily seem unfazed by occasions where they can't get aroused," he notes. "They tend to attribute it to benign external events--it was something they ate, or they're not getting enough sleep--not as characteristics of themselves." In contrast, men with arousal problems tend to do just the opposite, thinking of every instance of difficulty as a sign of a long-term internal problem, either physiological or psychological, he says.

At the Kinsey Institute, Janssen and John Bancroft, MD, the institute's director, have been developing a theoretical model and a set of measurement tools that define sexual arousal as the product of excitatory and inhibitory tendencies. Last year, they published papers in the Journal of Sex Research (Vol. 39, No. 2) describing the Sexual Inhibition and Sexual Excitation Scale--a new questionnaire that measures individual differences in the tendency to become sexually inhibited and excited.

Early research on the model suggests that while a single factor accounts for all of the variation among men in their tendency to become sexually excited (SES), there are two inhibitory factors--one that represents inhibition due to the threat of performance failure (SIS1) and one that represents inhibition due to the threat of such performance consequences as an unwanted pregnancy or a sexually transmitted disease (SIS2).

One implication is that people with different levels of SES, SIS1 and SIS2 will respond differently to different kinds of stimuli, says Janssen. In one study, for instance, Janssen, Bancroft and their collaborators found that people who scored highly on SIS2 were less likely to be aroused by erotic films that included threatening stimuli than people with low SIS2 scores.

"We believe that people who are high in inhibition-proneness are more vulnerable to developing sexual problems, whereas those who are low are more likely to engage in high-risk sexual behavior," says Janssen.

Physiological and subjective arousal

For most of the history of research on sexual arousal, studies involving women have been much rarer than studies involving men. Recently, however, the gap has started to narrow due to the work of psychologists such as Cindy Meston, PhD, of the University of Texas at Austin, Julia Heiman, PhD, of the University of Washington, and Ellen Laan, PhD, of the University of Amsterdam. Janssen and his colleagues at the Kinsey Institute have also begun studying female arousal.

One of the most interesting results to come out of that work, researchers say, is that there are significant differences between men and women in the relationship between physiological and subjective arousal.

"What we find in research in males is there's a very high correlation between their erectile response and how aroused they say they are," says Meston. "But in women we get low, if any correlations."

In addition to being interesting from a scientific standpoint, the sex difference could also have important implications for the treatment of female sexual dysfunction, says Meston. Researchers have not yet been able to pinpoint the source of the difference, she says, but some progress has been made.

Several explanations that once seemed likely candidates have been eliminated in recent years. One of them is the idea that women are less likely than men to talk honestly about their sexuality because of sexual taboos. But Meston says she sees no evidence of reticence in the women who volunteer for her studies.

Another possibility is that erotic films might evoke negative emotions in women, which could mask their arousal. But Laan and her collaborators at the University of Amsterdam have found no evidence that such reactions can account for the physiology-experience gap.

Meston and others suspect that the difference probably has something to do with the fact that male genital arousal is simply easier to notice than female genital arousal. Men also seem to be more attentive than women to all kinds of physiological signals, not just sexual ones, says Janssen.

An open question is whether the resulting sex differences in the relationship between physiological and subjective arousal are permanent, or whether they can be changed through training. Meston says her lab is currently conducting a study to find that out.