People eat out of habit, a study finds, even when food is stale

Being a creature of habit may mean mindlessly eating food, even when it’s stale.

An online study in the journal Personality and Social Psychology Bulletin looking at how certain cues and adjustments can affect our habits used two experiments involving mindless eating. In the first, 98 people were recruited to watch movie trailers and were given water and boxes of popcorn. The popcorn was either 1 week old and stale, or freshly popped. It was randomly doled out to the participants who had also been surveyed about how often they typically eat popcorn in movie theaters.

Those who who were very used to eating popcorn at the movies ate the same percentage of popcorn whether it was fresh or stale, while those who had moderate or weak habits of eating movie popcorn ate considerably less stale popcorn than fresh. Controlling for hunger didn’t alter the outcome.

Researchers also tested the habit theory in a different context -- a meeting room. While not in the familiar confines of a movie theater, would people be more aware of the fact that the popcorn was stale?

Here, taste mattered. Everyone ate less stale popcorn compared with fresh regardless of how strong their habit of eating movie popcorn.

In the second experiment, 89 movie-goers were asked to eat popcorn with their dominant or nondominant hand to see if that type of interference would disrupt their habits and alter how much they ate of stale and fresh popcorn. Eating with the nondominant hand caused those with moderate and high popcorn habits to eat less stale than fresh popcorn (those with low popcorn-eating habits ate about the same amount of fresh and stale popcorn, but researchers noted that they ate so slowly it caused a floor effect).

“People believe their eating behavior is largely activated by how food tastes. Nobody likes cold, spongy, week-old popcorn,” said study co-author Wendy Wood in a news release. Wood, provost professor of psychology and business at USC, added, “But once we’ve formed an eating habit, we no longer care whether the food tastes good. We’ll eat exactly the same amount, whether it’s fresh or stale.”

Brian Wansink, director of the Cornell University Food & Brand Lab, believes some easy changes -- switching from larger plates to smaller ones, for example -- could help us eat less without putting too much thought into it.

But in some situations, it may take more drastic measures to make us notice what we’re eating. “It’s not always feasible for dieters to avoid or alter the environments in which they typically overeat,” Wood said. “More feasible, perhaps, is for dieters to actively disrupt the established patterns of how they eat through simple techniques, such as switching the hand they use to eat.”