If you cheated on your spouse, would you admit it to a researcher? That question is one of the biggest challenges in the scientific study of marriage. 22 Surveys conducted in person are likely to underestimate the real rate of adultery because people are reluctant to admit such behavior not just to their spouses but to anyone. For example, researchers from the University of Colorado and Texas A&M surveyed 4,884 married women, using face-to-face interviews and anonymous computer questionnaires. 23 In contrast, on the computer questionnaire, more than 6 percent did. 

    A handful of new studies suggest surprising changes in the marital landscape in the United States. 24 For example, University of Washington researchers have found that the lifetime rate of infidelity for men over 60 increased from 20 to 28 percent to 15 percent. 25 About 20 percent of men and 15 percent of women under 35 say they have ever been unfaithful, up from about 15 and 12 percent, respectively, over the past fifteen years. While infidelity rates do appear to be rising, a vast majority of people still say adultery is wrong, and most men and women do not appear to be unfaithful.