Considering how universal, automatic, and potent these tendencies are, one might wonder: why doesn't everyone cheat? Obviously, everyone does not cheat, raising the question: why are some people better able at resisting this immediate temptation than others?

Recent research suggests the answer has a lot to do with cognitive control. The default state is to act on impulse. Overriding this requires mental effort, and the more attractive alternatives you have (imagine all the offers Tiger Woods received), the harder it is to control your impulses.

In recent years, neuropsychologists have located a set of brain areas located in the frontal lobe (around the forehead) of humans that support self-control processes. These so-called "executive functions", which were the last bit of our brain to evolve, involve the ability to plan, inhibit, or delay responding. Whenever someone must focus hard on a task and ignore distractions, this area is particularly active. The extent to which these areas of the brain light up predicts a lot of important outcomes, including whether people are likely to follow the rule norms of society, resist a wide variety of temptations, and engage in risky behaviors. Executive control even predicts the ability to resist the urge to eat M&M's when on a diet!

Therefore, executive control may play a role in cheating behaviors. If your long-term goal is to stay committed to your partner, and you've got a heck of a lot of temptation, this requires a heck of a lot of executive control. Executive control may also help people avoid situations in the first place where they may experience the lure of attractive potential partners.

Recent evidence suggests that executive functions do have a lot to do with cheating. Simone Ritter and her colleagues at Radboud University Nijmegen found that under normal conditions, romantically involved heterosexual individuals reported less interest in attractive opposite-sex individuals than those who were single. All bets were off though when they were cognitively taxed by the experimenter, such as given a heavy time pressure. In these situations, with their executive control guard down, there was no longer a difference between single and romantically involved individuals! It appears that romantically involved people only reject attractive potential partners when they have enough cognitive resources and time to decide.

In a hot-off-the-press study in the prestigious Journal of Personality and Social Psychology, Tila Pronk and her colleagues at Radboud University Nijmegen (the researchers at Radboud do awesome research!) looked at the issue more directly by scientifically investigating why some people have more difficulty than others in staying faithful to their romantic partners. Across three studies, they investigated the relation between a different aspect of executive control and people's ability to stay faithful.

In their first study, 72 romantically-involved students completed a task measuring their ability to shift between two sets of instructions. After completing the task of executive control, they completed a short questionnaire which asked them how good they are staying faithful to their partner (e.g., "If a cute guy/girl shows interest in me, I find it hard to resist temptation"). They found that those with lower executive control tended to report having a higher level of difficulty staying faithful. There were no gender differences. 

The skeptic may argue this may only pertain to self-reports. How do we know executive control is related to a real world inability to resist a temptation to cheat? Their second study addressed this issue. 22 heterosexual men completed a task of executive control that required the ability to keep letters in memory while simultaneously processing information. This task requires constant updating of memory, which taxes executive control processes. After completing the task, participants were asked to sit in the waiting room until the experimenter called them.

Then in walked an attractive female, who the experimenters recruited to help out with their experiment. The female was instructed by the experimenters to behave in a friendly, but not obviously interested or flirtatious manner. None of the participants reported being aware that the women was a part of the experiment. The interactions were videotaped and afterwards the women, and four independent observers, were shown the first 5 minutes of the interaction and judged how much the guy was flirting. All observers agreed with each other highly in their perceptions of the guy's flirting behavior. Consistent with their first study, they found that the lower the level of executive control, the greater the flirting behavior.

In their third and last study, they looked at whether executive control helps prevent people from ending up in a situation with an attractive alternative in the first place. Sixty-five men and women completed the famous Stroop Test, in which they had to name the color of a word while ignoring the meaning of that word. This is not an easy task: try it yourself!

After taking the measure of executive control, they were told they would be playing an "acquaintance game" with a randomly-assigned participant. They were shown a picture of this other participant (who just happened to be an attractive opposite-sex person!). In the first part of the game, participants selected questions they wanted to ask the other participant and in the second part, they answered questions that the other participant supposedly selected for them (e.g., "Would you like to be famous?"). The game lasted for 3 minutes, after which participants indicated how attractive they found the other participant by moving a slider somewhere between totally not attractive to very attractive. Then they indicated how much they would like to meet the other participant in real life.