Cheating at Sex? It Depends When President Bill Clinton stood before the world and declared, "I did not have sexual relations with that woman," he probably fooled no one. At least not after Monica Lewinsky's little blue dress surfaced. New research from the University of Michigan suggests that the vast majority of Americans see little difference between sexual intercourse and oral sex when it comes to infidelity. Psychologists find almost unanimous agreement that intercourse and several other behaviors, including emailing naked pictures of oneself and texting erotic messages, are serious infractions on the cheating index. Video: 1998: Clinton Denies Lewinsky Affair However, 456 college students who were asked to rate 27 different behaviors revealed considerable ambiguity over the relative seriousness of many activities. Hugging a member of the opposite sex for less than 10 seconds only scored 12.2 on a scale of 100, compared to 97.7 percent for intercourse and 41.4 for going out to dinner together. Oral sex was a close second to intercourse, with an average score of 96.8. The study, published in the journal Evolutionary Psychology, also found that the ratings were strongly influenced by how secure each participant felt in his or her own relationships. Those who felt they were not very secure in their relationships, a condition called "attachment anxiety," were likely to rate many activities as far more serious than participants who actively tried to avoid making strong commitments. "Attachment anxiety is when you are worried that your partner doesn't share the same feelings you do," social psychologist Daniel Kruger, lead author of the study, said in a telephone interview. You are worried that he or she is going to leave you. Those people, not surprisingly, were hypersensitive to anything that would threaten their relationship. Across the board, he added, they rated "ambiguous behavior higher because it's a warning sign to them. It's sort of like they have the smoke detector turned up. Video: Digital Infidelity By contrast, persons who were reluctant to make long-term commitments were much more likely to rate those same activities lower, so "someone sitting on my lap doesn't mean I'm cheating," said Kruger, who conducted the research with colleagues at the University of Michigan and three other universities. The difference in opinion is not just a matter of semantics, he added, because different values on different behaviors "could create conflicts" in their relationship. If a husband thinks sharing a hotel room with a female working companion to save money is all right (52.7 average,) but not the same bed (a jump to 68.4,) and his wife thinks it's a lot more serious, chances are there's going to be conflict there. Perhaps surprisingly, the study did not find strong gender differences among the participants. Some recent studies have indicated men are more upset when they imagine their partner being sexually unfaithful, and women tend to have stronger reactions if their partner forms deep emotional attachment to someone else (52.4 on the cheating index.) "We didn't find a parallel phenomenon here," Kruger said. Both men and women thought sex was cheating. They may have agreed on that, but there was considerable disagreement over the importance of some activities, depending on whether the participant felt secure in personal relationships, or didn't want to make commitments. Texting erotic messages, staying in the same hotel room, talking on the phone several times a week, and even holding hands was far more serious for those suffering from "attachment anxiety" than those wanting to avoid commitments. The researchers did not zero in on a form of sexual behavior that seems to be rampant these days -- cybersex. Kruger noted that they did include sending photos and erotic messages, but Web porn, which is available to anyone anywhere, probably figures in to a lot of troubled relationships. What is clear, however, is there is considerable disagreement over the seriousness of some behaviors, especially those that fall between sharing that hotel room (52.7) and telling dirty jokes (25.9.) But what does it all say about Clinton's efforts to fib his way out of a really messy situation? Offering just his own personal opinion, Kruger said he's not even sure the president was lying. Recalling another famous quote from that era ("It depends upon what the meaning of the word 'is,' is"), Kruger noted this: Bill Clinton said that he wasn't actually lying because he was looking at one of the reporters in the second row, because he in fact did not have sex with that woman (sitting in the second row). Lewinsky was a separate concept. That was my interpretation of why he worded it in such a strange way. But at least now we know he ranked second on the cheating index, not first.