survey found 75 percent of American men and 29 percent of American women experience orgasm virtually every time they have intercourse. That's not terribly startling. More interesting are the results of new studies that focus on the physiology of orgasm. Many experts say men and women are capable of having much more sexual pleasure than they might suspect. (In a truly astounding case, researchers in one lab found a man who had 17 orgasms in an hour and a woman who had 134.) Other studies are challenging the notion that the secret to orgasm lies in the genitals. Rutgers University researchers Beverly Whipple and Barry Komisaruk found that victims of spinal-cord injuries whose nerve pathways from the genitals have been severed often develop hypersensitive areas elsewhere on their body that, when stroked, will bring them to orgasm. They also looked at healthy women and found that the right caressing of the back, the neck, the hands or other favored spot would bring them to orgasm as well. Together with therapist Gina Ogden, Whipple and Komisaruk took it a step further and discovered that women can indeed reach full-blown orgasm through fantasy alone, with no body stimulation whatsoever. Nobody knows for sure why different stimulations trigger ecstasy. But Komisaruk hypothesizes that orgasm is a matter of the brain recruiting increasing numbers of sensory neurons to fire simultaneously until a threshold is crossed and ecstasy is unleashed. Not only is orgasm the peak of physical pleasure, it may have significant health benefits that mirror some of the salutary effects of exercise. Orgasm acts as a powerful pain-relief agent, and some studies suggest it bolsters immune functioning. The typical orgasm will boost the body's T3 and T4 lymphocyte cells--the cells that fight off foreign invaders--by up to 20 percent. In an ongoing study, Ohio University gynecologist Dudley Chapman has followed the progress of women with breast cancer and finds that the frequency of orgasm might aid their health progress; the more climaxes they have, the healthier they are. He discounts the idea that the beneficial impact of orgasm is due to the general love and support given the cancer victims by their lovers because several of the women who improved most live alone and masturbate to orgasm. "I don't want to wave any flags and say [orgasm] cures cancer," Chapman cautions. "Still, I'm optimistic that we're on to something here." THE SOCIAL SIDE OF SEX The Sex in America survey shows just how strongly societal norms rule bedroom behavior. Sexual impulses are not purely instinctive, untamable and unvarying among most ordinary men and women. Not only does society constrain what we do and with whom we do it, but social dictates affect what we think about and what we find arousing. The survey authors say Americans' sex lives, in large part, follow social "scripts" that influence everything from what's happening when potential sex partners encounter each other casually, to what they find alluring in each other and to their reactions to the impulses those encounters stir. For example, when males listen to the story of a woman entering a room, removing her clothes, a man entering and various activities occurring, they will often be sexually aroused if told the man is her boyfriend. But the same script will not arouse them if told the man is her doctor. One trouble with scripts is that they can sometimes lead people to act in inappropriate or harmful ways. In general, researchers have found that men are more prone than women to read sexual implications into casual encounters. That may explain the results of a University of New Orleans study that found men thought women had initiated sexual encounters in far more instances than the women themselves said they had. "The survey shows how troubled the relationship between the sexes still is," says Gagnon, because the signals men and women are trying to send each other often get confused. The power of social scripts also extends to more benign sexual encounters. When instances of rape are not included, research at the University of Kansas suggests that men actually engage in more unwanted sex than women, perhaps because of the societal expectation that men have stronger desires than women and should therefore be more eager for sex. Other evidence shows wives tend to initiate more and more sex as each year of marriage goes by, which might reflect how they are freeing themselves from stigmas against acting on sexual impulses that they picked up when they were younger. Sometimes, however, basic sexual arousal prevails over societal taboos. For instance, much pornography is so appealing that it has managed to survive from the days of cave drawings and thrives even in today's disapproving society. The Sex in America survey shows that 41 percent of men and 16 percent of women buy erotica in the course of a year. And even though women say they're less turned on by erotica, lab researchers find they are usually just about as aroused as men and even tend to be slightly more "turned on" if the plot features a woman as the main character. But even when breaking the rules, Americans often keep them in mind. Virtually all viewers of pornography prefer highly conventional sex acts between consenting adults and are disturbed by acts that deviate from the norm, according to Clive Davis at Syracuse University. GOOD SEX, BAD SEX With all the modern folklore about what constitutes great sex, it's easy to forget that for a significant portion of Americans, sex can be the source of deep anxiety if not outright misery. One in 5 women and 1 in 10 men told Sex in America surveyors that sex is not pleasurable for them. The American Urological Association reports that 30 million men a year have trouble with erections, and 20,000 get penile implants to help with their dysfunction. Clinicians say that men also complain about their inability to control the timing of ejaculation, and both sexes routinely report problems with desire. Twenty years ago, such individuals were automatically assumed to be racked with mental problems. "Today the pendulum has shifted to the other extreme, where everything is medicalized," says Raul Schiavi, director of the Human Sexuality Program at the Mount Sinai Medical Center in New York. The reality is that true sexual dysfunction often stems from a mix of mental and physical problems. An even greater reality is that many of the "problems" that therapists are asked to cure are actually quite normal sexual behaviors. Those patients only need accurate information about the range of sexual normalcy. Even with the abundance of tell-all talk shows and pop sex advice books, therapists still see plenty of men who think they're sick because they masturbate and women who think they're frigid because they can't reach orgasm