Want to eat less? Try using your non-dominant hand

Much of our eating behaviour is habitual. Many of us eat biscuits with tea, nibbles before dinner, popcorn at the cinema and so on. A new study by David Neal and his colleagues has put these habits under the microscope and shown just how entrenched they can become and how they can be broken.

One hundred and fifty-eight participants were recruited to either watch movie trailers at a cinema or music videos in a university department meeting room. In both settings they were given popcorn to eat, which was either stale or fresh. Now, some of the participants were habitual popcorn eaters at the movies, others weren't. The notable finding was that in the cinema setting the habitual popcorn eaters ate just as much of the popcorn when it was stale as when it was fresh. This they did even though they said they liked it less (just as the non-habitual popcorn eaters did), and regardless of whether they were hungry or not. Neal's team said this highlights how habits are driven by context (the cinema) and are immune to attitudes (i.e. liking) and motivation (i.e. hunger). By contrast, when in the department meeting room (not the usual setting for eating popcorn), the habitual popcorn eaters ate less of the stale popcorn and their consumption was influenced by hunger. This shows that if you escape the context that usually drives a habit then its power weakens and motives and intentions can take over.

A second study was similar to the first except this time half the participants were told to eat the popcorn with their non-dominant hand (i.e. right-handers had to eat with their left). This manipulation, which obstructs the automatic execution of a habit, had a similar effect to changing the environmental context. Habitual popcorn eaters allowed to use their dominant hand again ate just as much stale popcorn as fresh, in spite of liking it less, and regardless of their hunger levels. But those instructed to use their non-dominant hand were freed of their usual habit - they ate less of the stale popcorn and their consumption was driven more by hunger and liking.

"Habit change may ... require impeding habit activation [by contexts] or interrupting fluid habit execution," the researchers said. "Although our findings suggest that both avenues are effective, it is not always possible for dieters to avoid or alter the environments in which they typically overeat. More feasible, perhaps, is for dieters to actively disrupt the execution of the activated eating sequence by simple manipulations such as eating with the non-dominant hand and, in so doing, bring their eating under their personal control."
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Neal, D., Wood, W., Wu, M., and Kurlander, D. (2011). The Pull of the Past: When Do Habits Persist Despite Conflict With Motives? Personality and Social Psychology Bulletin DOI: 10.1177/0146167211419863

Further reading: How to form a habit.
Seven ways to be good.

Post written by Christian Jarrett for the BPS Research Digest.