The terminology “extradyadic” sex (EDS) is chosen as the concept is more inclusive than referring to marital relationships and due to the number of common-law relationships, more recent research might prefer a more inclusive terminology. The following research however, mostly refers to infidelity among marital couples and vaginal sex outside the marital relationship.
Study 1: Drigotas, S., & Barta, W (2001). The cheating heart: Scientific Explorations of Infidelity. Current Directions in Human Sexuality and Intimate Relationships, 192-.
Method: Descriptive research based on retrospective self-report data.
- Descriptives: Researchers reported that 37% of men and 12.4% of women born between 1933 and 1942 have engaged in EDS. For those born between 1953 and 1974 it was 27.6% for men and 26.2% for women. Researchers reported that more men than women reported sexual motivation versus emotional motivation.
- Divorce: More men see infidelity as a reason for divorce compared to women, but if the female partner considered herself to be more attractive to her cheating spouse, she was more likely to seek divorce as a consequence of his infidelity :).
- Opportunity: The decrease in gender differences of reported infidelity seems to be a direct consequence of opportunity (working outside the home with opposite genders), as well as greater economic independence and it is also correlated to an increase in marital instability.
- Familiarity and normalisation: Those who know someone who is engaging in EDS is more likely to follow suit.
- Marital satisfaction: although more recent research shows a correlation between marital dissatisfaction and EDS, historically men were more likely to be unfaithful even if reported marital satisfaction was high.
- Committment: Highly committed individuals are less likely to engage in EDS. They consider the long-term consequences and therefore are motivated to derogate potential alternatives (seeing them as unattractive) to protect the marriage.
Study 2: Atkins, D., Baucom, D., & Jacobson, N. (2001). Understanding Infidelity: Correlates in a National Random Sample. Journal of Family Psychology, 15(4), 735-749.
Method: National Opinion Research Center, University of Chicago. Survey dates from 1972 to 1994. Number of participants 3,000.
- Marital satisfaction: those reported to be “pretty happy” were twice as likely to report EDS compared to those reported to be “very happy”.
- Opportunity-income-power and status: women and men with an income 75,000 and more were 1.5 times more likely to have EDS, compared to those earning up to 30,000 per year. Employment, status, income and opportunity (travel) are closely related.
- Religious Services: Those never attending religious services were 2.5 times more likely to have EDS compared to those who attended religious services more than once a week.
- Age at marriage: Likelihood of EDS was reported four times higher among those married at age 16 versus those married at age 23 and older.
Study 3: Authors: Lammers, J., Stoker, J., Jordan, J., Pollmann, M., & Stapel, D. (2011). Power Increases Infidelity Among Men and Women. Psychological Science Online, 30, 1-7.
Method: emails to readers of a Dutch magazine. Number of participants, 1,275 of which 46% female and 54% male. Mean age 39.1 (SD 8.2 years).
- Power: Power is associated with increased self-reported EDS and with an intention to engage in EDS. Power increased confidence and increases the psychological distance to their partner (also due to other correlates such as travel and employment requirements).
- Gender: gender did not moderate the above findings. Power independent of gender has a positive relationship to EDS.
Study 4: Whisman, M., Coop Gorden, K., & Chatav, Y. (2007). Predicting sexual infidelity in a population-based sample of married individuals. Journal of Family Psychology, 21(2), 320-324.
Method: 2, 291 married participants were drawn from a National Comorbidity Survey, a nationally representative survey based on a stratified sample of people aged 15-54.
- Personality characteristics: Neuroticism (impulsivity and low dependability) was a significant predictor of EDS.
- Religion: Religiosity was negatively associated with EDS.
- Marital functioning: EDS was predicted by greater marital dissatisfaction
- Parenting variables: Husbands whose wives are pregnant are more likely to engage in EDS.