A great deal of psychology research has pursued this particular line, demonstrating, for example, that willpower seems to be a finite resource. Expend it in one situation and you'll have less left over for another.
A new study by Jessie de Witt Huberts and her colleagues at Utrecht University takes a different perspective. They point out that we often over-indulge, not because we can't help it, but because we reason that it's okay to do so. After that half-hour run, we tell ourselves, we deserve the doughnut! de Witt Huberts' team call this self-licensing and they say it's surprisingly under-researched.
Previous studies have shown how self-licensing affects our choices. For example, after working harder, people are more likely to choose a cake over a fruit-salad. But before now, no-one's looked to see how self-licensing might affect actual indulgent consumption.
Before they got started, de Witt Huberts and her team had to confront a complication with researching this topic - the need to separate out the effects of low energy from self-licensing. If someone's been working hard, not only might this encourage them to think they deserve a naughty snack, their lack of energy might also deplete their willpower (indeed, studies have suggested that low sugar levels reduce willpower).
To get around this problem, de Witt Huberts and her colleagues needed a way to trick people into thinking they'd worked hard (inviting self licensing) without actually diminishing their willpower levels. They did this by having participants test-out what they were told was a new screening tool for dyslexia. It involved looking at 200 words on a computer screen, one at a time, and pressing the key on the keyboard that corresponded to the first letter of each word. Crucially, one group of participants did this for five minutes, and were then told they had to do it all over again for another five minutes to check the reliability of the screening tool. The other participants simply had a one-minute break between two 5-minute sessions.
In a pilot study with 106 women, the group who thought they'd had to test the screening tool twice, felt like they'd worked harder than the other group, who thought they'd done it just once (even though both groups had worked for the same length of time). Next, both groups completed the Stroop test, a classic measure of self control that requires people to read colour words (e.g. blue), whilst ignoring the ink colour they're written in. This test confirmed that both groups had the same levels of self control even though one group felt like they'd worked harder than the other.
When it came to the study proper, 39 women were split into two groups - one did the dyslexia screening tool in two phases, to make them feel like they'd worked harder, and the other group did it in one bash. Next, ostensibly as part of a separate consumer research study, all the women taste-tested some crisps, M&Ms, Wine gums and Chocolate chip cookies.
The take-home finding? Both groups said their willpower levels felt the same, but the women who thought they'd worked harder tended to eat more of the naughty food. In the ten minutes available, they consumed an average of 26 grammes of more snack-food, which equated to 130 more calories. As well as feeling like they'd worked harder, they also said they felt more hungry, but this wasn't correlated with the amount they ate. The researchers speculated that the feelings of hunger could have been a further form of self-licensing - "I've worked hard and I'm hungry".
This study is one of the first steps towards uncovering the part that self-licensing plays in giving in to temptation. It's limited in that the sample only included women and the self-licensing was implicit. The women who thought they'd worked harder were more indulgent, but we don't know anything about the way they reasoned with themselves, or if the effect was conscious at all. "Nevertheless," the researchers concluded, "although many questions about self-licensing require further investigation, the current studies demonstrate that sometimes people strategically choose to indulge and that gratification of our desires is not inevitably governed by our impulses."
ESSIE C. DE WITT HUBERTS, CATHARINE EVERS, and DENISE T. D. DE RIDDER (2012). License to sin: Self-licensing as a mechanism underlying hedonic consumption. European Journal of Social Psychology DOI: 10.1002/ejsp.861
Post written by Christian Jarrett for the BPS Research Digest.