Do you have what it takes to resist temptation? Or do you find yourself indulging too often in a decadent dessert, using company time to check Facebook, or foregoing morning exercise in favor of sleep? We do not need a science experiment to understand the universality of cravings, desires and longings, or to understand how human desire serves as a double-edged sword. Urges motivate us in positive and important ways - to seek food, find shelter, make friends, get sleep, procreate. But left unchecked, our urges and desires can lead to a myriad of negative consequences, from obesity and poor health to reduced productivity, overspending, damaged relationships, substance abuse, and violence.
If your willpower is weak, a little divine intervention may help. In a series of studies, Kevin Rounding and colleagues tested participants' self-control by asking them to endure discomfort to earn a reward, or to delay immediate payment to obtain a larger stipend. Before the test of self-control, half of the participants were exposed to words with religious themes (e.g., divine, spirit, God) in a puzzle-solving task, and half completed the same task without the religious primes. Those who saw the primes were willing to endure greater discomfort and delay gratification longer than those who did not. Additional studies showed that religious primes also fortified self-control after the fact. In these studies, participants first attempted to resist temptation, and afterward half of the participants viewed religious primes while the other half did not. Finally, all participants were faced with an additional task involving self-restraint. Exposure to the religious words refueled resolve, as participants who saw the religious primes were able to persist at a frustrating task far longer than those who did not.
Resisting temptation can be difficult, especially if it involves repeated self-denial. Indeed, entire industries have evolved to provide support for those who have trouble saying "no" (consider weight loss and smoking cessation programs). Research by Roy Baumeister, Kathleen Vohs, and Dianne Tice sheds light on why self-control can be so elusive. According to Baumeister and colleagues, self-control operates in many ways like a muscle: It depends on a limited energy source that can be depleted. Thus with overexertion, particularly in a short time frame, self-control will fatigue and ultimately fail.
Support for the notion that self-control taxes a limited resource, and that depletion of this resource will lead to lapses in resistance, comes from studies that measure individuals' ability to resist temptation on consecutive tasks. In these studies, some participants first performed a self-control task (e.g., passing up chocolate chip cookies and instead eating a healthier alternative), while others performed a task that allowed them to indulge (e.g., eating the cookies). The critical question is how the experience of resisting temptation affected self-control when individuals were then immediately given another self-control challenge (e.g., solving a difficult puzzle without getting frustrated). Although researchers have varied both the initial temptation and the subsequent self-control challenge across studies (including physical, intellectual, and emotional enticements), the pattern of findings has been the same: People who successfully deny an urge or desire are less likely to regulate their behavior if faced with another test of self-control shortly thereafter.
This ego-depletion, as Baumeister and colleagues call it, occurs not only in the lab but in everyday experience as well. In a recent study, adults carried smart phones for a week, and were queried about their cravings at seven random times every day from early morning until late at night. When signaled, participants were to report whether or not they had experienced a desire within the last 30 minutes, and to indicate the nature of the desire (e.g., eating, coffee, sex, sleep, alcohol, social media, tobacco, spending, etc.). They also indicated the strength of the desire, whether it conflicted with other goals, whether they attempted to resist the desire, and whether they fulfilled the desire. When individuals repeatedly denied their impulses in a given day, the likelihood that they would give in to future temptations that day increased. This heightened vulnerability to temptation occurred even when the urges varied over the day, suggesting that the simple act of self-denial, regardless of what we are denying, weakens our global resolve.