Infidelity
Infidelity is a violation of a couple's emotional or sexual exclusivity that commonly results in feelings of anger, sexual jealousy, and rivalry.
What constitutes infidelity depends on expectations within the relationship. In marital relationships, exclusivity is commonly assumed. Infidelity can cause psychological damage, including feelings of rage and betrayal, depression, low sexual and personal confidence, and even post-traumatic stress disorder. People of both sexes can experience social consequences if their act of infidelity becomes public, but the form and extent of these consequences can depend on the gender of the unfaithful person.
Incidence
After the Kinsey Reports came out in the early 1950s, findings suggested that historically and cross-culturally, extramarital sex has been a matter of regulation more than sex before marriage. The Kinsey Reports found that around half of men and a quarter of women studied had committed adultery. The Janus Report on Sexual Behavior in America also reported that one-third of married men and a quarter of women have had an extramarital affair.According to The New York Times, the most consistent data on infidelity comes from the University of Chicago's General Social Survey. Interviews with people in monogamous relationships since 1972 by the GSS have shown that approximately 12% of men and 7% of women admit to having had an extramarital relationship. Results, however, vary year by year, and also by age-group surveyed. For example, one study conducted by the University of Washington, Seattle, found slightly, or significantly higher, rates of infidelity for populations under 35, or older than 60. In that study, which involved 19,065 people during a 15-year period, rates of infidelity among men were found to have risen from 20% to 28%, and rates for women ranged from 5% to 15%. In more recent nationwide surveys, several researchers found that about twice as many men as women reported having an extramarital affair. A survey conducted in 1990 found that 2.2% of married participants reported having more than one partner during the past year. In general, national surveys conducted in the early 1990s reported that between 15 and 25% of married Americans reported having extramarital affairs. People who had stronger sexual interests, more permissive sexual values, lower subjective satisfaction with their partner, weaker network ties to their partner, and greater sexual opportunities were more likely to be unfaithful.
Rates of infidelity among women are thought to increase with age. In one study, rates were higher in more recent marriages, compared with previous generations. Men were found to be only "somewhat" more likely than women to engage in infidelity, with rates for both sexes becoming increasingly similar. Another study found that the likelihood of women being involved in infidelity reached a peak in the seventh year of their marriage and then declined afterward. For married men, the longer they were in relationships, the less likely they were to engage in infidelity, until the eighteenth year of marriage, at which point the chance of men engaging in infidelity began to increase.
Research on pregnancy and its effects on sexual desire and rates of infidelity conducted in southern Spain indicated that men were more likely to engage in infidelity while their partner was pregnant. It was estimated that 1 in 10 fathers-to-be engaged in infidelity at some point during their partner's pregnancy and suggested that the likelihood of the man engaging in infidelity increases as the woman's pregnancy progresses through its trimesters.
One measure of infidelity is paternal discrepancy, a situation that arises when someone who is presumed to be a child's father is in fact not the biological parent. Frequencies as high as 30% are sometimes assumed in the media, but research by sociologist Michael Gilding traced these overestimates back to an informal remark at a 1972 conference. The detection of paternal discrepancy can occur in the context of medical genetic screening, in genetic family name research, and in immigration testing. Such studies show that paternal discrepancy is, in fact, less than 10% among the sampled African populations, less than 5% among the sampled Native American and Polynesian populations, less than 2% of the sampled Middle Eastern population, and generally 1–2% among European samples.
Gender
Differences in sexual infidelity as a function of gender have been commonly reported. The National Health and Social Life Survey found that 4% of married men, 16% of cohabiting men, and 37% of dating men engaged in acts of sexual infidelity in the previous year compared to 1% of married women, 8% of cohabiting women, and 17% of women in dating relationships. These differences have been generally thought due to evolutionary pressures that motivate men towards sexual opportunity and women towards commitment to one partner. In addition, recent research finds that differences in gender may possibly be explained by other mechanisms including power and sensations seeking. For example, one study found that women in more financially independent and higher positions of power, were also more likely to be more unfaithful to their partners. In another study, when the tendency to sensation seek was controlled for, there were no gender differences in the likelihood to being unfaithful. These findings suggest there may be various factors that might influence the likelihood of some individuals to engage in extradyadic relationships, and that such factors may account for observed gender differences beyond actual gender and evolutionary pressures associated with each.Gender differences
There is currently debate in the field of evolutionary psychology whether an innate, evolved sex difference exists between men and women in response to an act of infidelity. A study published in 2002 suggested there may be sex differences in jealousy. Those that posit a sex difference exists state that men are 60% more likely to be disturbed by an act of sexual infidelity, whereas women are 83% more likely to be disturbed by an act of emotional infidelity. Those against this model argue that there is no difference between men and women in their response to an act of infidelity. From an evolutionary perspective, men are theorized to maximize their fitness by investing as little as possible in their offspring and producing as many offspring as possible, due to the risk of males investing in children that are not theirs. Women, who do not face the risk of cuckoldry, are theorized to maximize their fitness by investing as much as possible in their offspring because they invest at least nine months of resources towards their offspring in pregnancy. Maximizing female fitness is theorized to require males in the relationship to invest all their resources in the offspring. These conflicting strategies are theorized to have resulted in selection of different jealousy mechanisms that are designed to enhance the fitness of the respective gender.A common way to test whether an innate jealousy response exists between sexes is to use a forced-choice questionnaire. This style of questionnaire asks participants "yes or no" and "response A or response B" style questions about certain scenarios. For example, a question might ask, "If you found your partner cheating on you would you be more upset by the sexual involvement or the emotional involvement". Many studies using forced choice questionnaires have found statistically significant results supporting an innate sex difference between men and women. Furthermore, studies have shown that this observation holds across many cultures, although the magnitudes of the sex difference vary within sexes across cultures.
Although forced-choice questionnaires show a statistically significant sex-difference, critics of the theory of evolved sex differences in jealousy question these findings. In consideration of the entire body of work on sex differences, C. F. Harris asserted that when methods other than forced-choice questionnaires are used to identify an innate sex difference, inconsistencies between studies begin to arise. For example, researchers found that women sometimes report feeling more intense jealousy in response to both sexual and emotional infidelity. The results of these studies also depended on the context in which the participants were made to describe what type of jealousy they felt, as well as the intensity of their jealousy.
In her meta-analysis, Harris raises the question of whether forced choice questionnaires actually measure what they purport: jealousy itself and evidence that differences in jealousy arise from innate mechanisms. Her meta-analysis reveals that sex-differences are almost exclusively found in forced-choice studies. According to Harris, a meta-analysis of multiple types of studies should indicate a convergence of evidence and multiple operationalizations. This is not the case, which raises the question as to the validity of forced-choice studies. DeSteno and Bartlett further support this argument by providing evidence which indicates that significant results of forced-choice studies may actually be an artifact of measurement; this finding would invalidate many of the claims made by those "in favor" of an "innate" sex difference. Even those "in favor" of sex-differences admit that certain lines of research, such as homicide studies, suggest against the possibility of sex-differences.
These inconsistent results have led researchers to propose novel theories that attempt to explain the sex differences observed in certain studies. One theory that has been hypothesized to explain why men and women both report more distress to emotional infidelity than sexual infidelity is borrowed from childhood attachment theories. Studies have found that attachment styles of adults are consistent with their self-reported relationship histories. For example, more men are reported to have an insecure, dismissing avoidant attachment style; where these "individuals often attempt to minimize or constrict emotional experience, deny needs for intimacy, are highly invested in autonomy, and are more sexually promiscuous than individuals who have other attachment styles". Levy and Kelly tested this theory and found that adult attachment styles strongly correlate to which type of infidelity elicited more jealousy. Individuals who have secure attachment styles often report that emotional infidelity is more upsetting whereas dismissing attachment styles were more likely to find sexual infidelity more upsetting. Their study did report that men in general were more likely than women to report sexual infidelity as more distressing, however this could be related to more men having a dismissing attachment style. The authors propose that a social mechanism may be responsible for these results. Similar studies focusing on the masculinization and feminization by society also argue for a social explanation, while discounting an evolutionary explanation.
A 2015 study found a correlation between AVPR1A expression and predisposition to extrapair mating in women but not in men.