every time they have intercourse. "The more research I do, the more I realize how normal most people are and how few realize it," says Donald Strassberg, a sex therapist and psychology professor at the University of Utah. Though most men will ejaculate within two to six minutes with genital stimulation, for example, many feel inadequate if they can't hold out for much longer periods. One of the most promising areas of research is focused on the sexuality of aging people. Many complain of low desire, and that has created the widespread impression that the golden years mean the end of one's sex life. But work by Helen Singer Kaplan and Richard Cogan at Cornell Medical Center shows that lack of testosterone is often the culprit and that tiny doses of it can return a zesty libido to many women who have lost their drive. (Research on the impact of giving testosterone doses to older men is underway.) "The difference between sexually satisfied and unsatisfied older couples is primarily one of attitude," says Schiavi. "Those who don't cling to unrealistic notions--say that the man should always have a rigid penis--find that sex provides just as much pleasure as ever." Though fears of sexual deviance or dysfunction are unfounded for the vast majority of the population, there are distinct subgroups with severe sexual sicknesses who do pose a danger to others. Unfortunately, researchers know little about the causes of these problems because they start during childhood or early adolescence years. Since most parents are loath to let researchers near their children to talk about sex, it is likely to take years to unearth the roots of severe deviance. BEYOND THE MEASURING STICK There are certain aspects of sexuality that survey research and laboratory experiments cannot illuminate, argues therapist Gina Ogden, author of the new book, Women Who Love Sex. She is a kind of anthropologist gathering stories from couples that focus on the emotional side of arousal. Her work centers on people like Judy Tobin, a subject who comes to orgasm without touching herself. That has been confirmed in a lab, but it doesn't reveal much about the role sexuality plays in her life. As it turns out, Tobin was raised as a "good little Jewish girl" to think sex and masturbation were bad. She lived a commonplace life with two kids and two cars in the New Jersey suburbs, until the day she decided she felt dead inside and left her marriage. As she and her second husband, Paul, explored their sexuality, they both discovered capabilities like the ability to "think off" (to come to orgasm through fantasy) or to create orgasmic states just by breathing in certain ways. For now, one can only guess how many people have secretly experienced phenomena like this. But researchers like Bernie Zilbergeld and Carol Ellison are trying to form a larger picture of the less definable aspects of sex by polling 2,600 women across the nation and allowing for expansive, essay-like answers to questions such as: What exactly do you like about sex? How important is it whether or not you have an orgasm? Beyond those deeply personal issues lie some enormous social ills that are linked to some aspects of Americans' sexual behavior. The AIDS epidemic and the teen-pregnancy problem have worsened at least in part because of the public's squeamishness about asking basic questions about sex and conveying explicit information about it. The Sex in America survey and other sexuality research projects will do two things. They will help fill gaps in our understanding of how to address these cultural problems. And they will help explain the source of the greatest human pleasure. That's not a bad marriage at all. SEX IN AMERICA SURVEY Here are some of the major highlights from the University of Chicago pathbreaking sex survey of 3,432 Americans: ROMANCE HOW MANY PARTNERS: 71 percent of Americans have only one sexual partner in the course of a year. 12 percent have none. Only 3 percent have five or more. 53 percent had one sex partner in the last five years. Median number of partners since age 18 reported by men: 6; women: 2 HOW OFTEN: Men: 6.5 times a month; Women: 6.3 times One third of Americans have sex at least twice a week. A third have sex a few times a month. The final third have sex a few times a year or not at all. About 40 percent of married people and over half of people living together have sex twice a week. 25 percent of singles living alone have sex that often. Percentage of people who married without first living together-- Born 1933-42. Men: 84.5, women: 93.8 Born 1963-74. Men: 33.9, women: 35.3 MARRIAGE LIKE ATTRACTS LIKE: Married couples share many key traits--Same race: 93 percent; Within 5 years in; age: 78 percent; Similar education: 82 percent; Same religion: 72 percent MARITAL BLISS: Spouses who enjoy great sexual pleasure: 88 percent Who enjoy great emotional satisfaction: 85 percent INFIDELITY: Wives who have ever had an affair: 15 percent; Husbands: 24.5 percent 37 percent of men in their 50s have had an affair; 12.4 percent of women that age have. 94 percent of married people were faithful in the past year. ORGASM: 75 percent of men but just 29 percent of women always have an orgasm during sex. 4 percent of women and 1 percent of men never have an orgasm. HOW LONG SEX LASTS: Most spend between 15 minutes and an hour having sex. 20 percent of men and 15 percent of women spend over an hour. Married men are five times more likely than single men to spend 15 minutes or less on sexual intercourse. PRACTICES TURN-ONS: The sexual practices that appeal most to Americans: 1. vaginal intercourse 2. watching mate undress 3. receiving oral sex 4. giving oral sex All other practices, such as group sex or sex with a stranger, appeal to only a small minority of Americans. MASTURBATION: The more active your sex life, the more likely it is that you masturbate. 60 percent of men and 40 percent of women masturbated in the past year. Among couples living together, that increases to 85 percent of men and 45 percent of women. About 25 percent of men and 10 percent of woman masturbate at least once a week. EROTICA: 41 percent of men and 16 percent of women purchased erotic materials in the past year