Out on a shopping trip after lunch, you buy a couple of boxes of chocolates to put in storage for enjoyment over the festive break. You're not particularly hungry, and you see no obvious problems with the plan. Later that night, however, the munchies kick in and before you know it you're raiding the cupboard, tearing open the box and gorging yourself. According to a new paper by Loran Nordgren and colleagues, such lapses occur all to frequently because of our inability, when satiated, to fully recognise the power of our visceral needs when hungry, tired, or lustful. They call this the "cold-to-hot empathy gap". They say that when we're satiated, as we are most of the time, we overestimate our ability to resist temptation - a phenomenon they've dubbed the "restraint bias".
The researchers first demonstrated this in relation to mental fatigue. One group of students performed an easy two-minute memory task whilst a second group completed an arduous twenty-minute version. The group who'd completed the easy version subsequently rated their ability to overcome mental fatigue more highly than the group who'd performed the arduous task. What's more, the easy group said they planned to leave more of their coursework until the last week of term, consistent with their inflated belief in their ability to work through fatigue.
A second study involved students who were either arriving or leaving the college cafeteria. The students ranked seven snack bars from least favourite to favourite and then had to choose one bar to take away. If they brought it back in a week's time, they'd get to keep the bar and win $4. You guessed it - compared with the hungry students arriving at the cafeteria, the departing students (who'd eaten) rated their self-control more highly, were more likely to choose to take away their first or second favourite snack bar, and were more likely to eat that bar during the following week.
It doesn't end there. In a third study, the researchers contrived to influence beliefs about self-control by giving student smokers a bogus implicit test of impulse control. Later, the students were challenged to watch the film "Coffee and Cigarettes" whilst abstaining from smoking. They were promised a greater cash reward the more difficult they made the challenge for themselves. In this case, students given bogus test feedback indicating they had high self-control were more likely to opt for greater temptation - holding the cigarette in their hand rather than having it on the desk - and they were more likely to give in to that temptation.
Finally, Nordgren's team tested the idea that "restraint bias" could explain why drug addicts are so prone to relapse. They recruited 55 participants through a smoking-cessation programme, all of whom had been smoke free for at least three weeks. Those who said they had more impulse control also tended to say they wouldn't be trying so hard to avoid temptation, such as the company of other smokers. Four months' later, those with the inflated sense of impulse control were more likely to have relapsed.
"The restraint bias suggests that people are willing to experiment with addictive drugs simply because they believe they can overcome the addiction," the researchers said. "An urgent task for future research is to test whether enduring shifts in impulse-control beliefs can be created."
Nordgren, L., van Harreveld, F., & van der Pligt, J. (2009). The Restraint Bias: How the Illusion of Self-Restraint Promotes Impulsive Behaviour. Psychological Science, 20 (12), 1523-1528 DOI: 10.1111/j.1467-9280.2009.02468.x