Infidelity - Incidence of Infidelity - Gender Differences in Infidelity

Gender Differences in Infidelity

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; this is often called a "sex difference". Those that posit a sex difference exists state that men are more likely to be disturbed by an act of sexual infidelity (having one’s partner engage in sexual relations with another), whereas women are more likely to be disturbed by an act of emotional infidelity (having one’s partner fall in love with another). Those against this model argue that there is no difference between men and women in their response to an act of infidelity.

One evolutionary hypothesis is based on a theory that aspects of cognition are retained in one’s genes. These genes are theorized to code for cognitive modules that have been shaped by evolution to perform a specific task. In our case, they would code for a sex specific jealousy response. 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 (A) the sexual involvement or (B) the emotional involvement". As the name implies, one is forced to choose between the two options. 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, these findings are questionable when the entire body of work on sex-differences is considered. When methods other than forced-choice questionnaires are used to identify an innate sex difference, inconsistencies between studies begin to arise. For example, in a study by Sangrin & Guadango (2005), the authors 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. From this study, it is clear that context plays a role in the responses men and women give researchers and therefore how sex-differences are interpreted.

In her meta-analysis, Harris (2003) 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 (2002) 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. In Levy & Kelly’s (2010) study, subsets of men were observed to show more emotional jealousy than sexual jealousy, a contradiction from the evolutionary theorists’ perspective. In an attempt to explain findings such as these, Levy & Kelly propose that differences between sexes, and within sexes, may be a result of the attachment they feel towards their partner. Their findings indicate that men who are more deeply attached to their partner have a greater chance of feeling more emotional jealousy versus sexual jealousy. The authors propose that a social mechanism may be responsible for the observed results. In other words, replicable sex differences in emotion and sexual jealousy could be a function of a social function. Similar studies (Ward & Voracek, 2004) focusing on the masculinization and feminization by society also argue for a social explanation, while discounting an evolutionary explanation.