It may come as a surprise to takeaway lovers, but scientists have found people don't keep eating junk food just because it is tasty., Instead they found we are such creatures of habit that once we have associated a place with a certain kind of food, like popcorn at the cinema, we will keep eating it - even if it's stale., Researchers from the University of Southern California devised a test to see what causes us to overeat., They gave people about to enter a cinema a bucket of just-popped fresh popcorn, or stale week-old popcorn., Moviegoers who didn't usually eat popcorn at the movies ate much less stale popcorn than fresh popcorn because it just didn't taste good.
But those who said they typically had popcorn at the movies ate about the same amount of popcorn whether it was fresh or stale.
In other words, for those in the habit of snacking at the movies, it made no difference whether the popcorn tasted good or not.
Co-author Wendy Wood from USC, said: 'People believe their eating behaviour is largely activated by how food tastes. Nobody likes cold, spongy, week-old popcorn.
'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.'
The study, in the current issue of the journal Personality and Social Psychology Bulletin, has important implications for understanding overeating and the conditions that may cause people to eat even when they are not hungry or do not like the food.
Lead author David Neal said: 'When we've repeatedly eaten a particular food in a particular environment, our brain comes to associate the food with that environment and makes us keep eating as long as those environmental cues are present.'
The researchers also gave popcorn to a control group watching movie clips in a meeting room, rather than in a cinema.
In the meeting room, a space not usually associated with popcorn, it mattered a lot if the popcorn tasted good. Outside of the cinema context, even habitual movie popcorn eaters ate much less stale popcorn than fresh popcorn, demonstrating the extent to which environmental cues can trigger automatic eating behaviour.
'The results show just how powerful our environment can be in triggering unhealthy behaviour,' Mr Neal said.
'Sometimes willpower and good intentions are not enough, and we need to trick our brains by controlling the environment instead.'
In a further experiment, researchers found they could also disrupt eating habits by asking participants to eat the popcorn with their non-dominant hand.
This caused them to pay more attention to what they were eating and so ate much less stale popcorn.
'It's not always feasible for dieters to avoid or alter the environments in which they typically overeat,' Miss 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.'