One of the most obvious cognitive bias’ that has application to the understanding and treatment of obesity is the unit bias. Unit bias is a “sense that a single entity (within a reasonablerange of sizes) is the appropriate amount to engage, consume, or consider.” In regards to food, people will think that a “unit” like a single package, tablespoon, plate, bowl, ect is the right amount of something to eat. If you click the above link you can read more about the unit bias.
Today, the good folks at Obesity Panacea posted some new info on the unit bias. They discuss a new study in Obesity that looked at the effect of 100-calorie snack packs on voluntary consumption between overweight and normal weight individuals.
If there is a unit bias, then 100-calorie snacks packs (which have come under much fire) should lead people to eat less. If so, then maybe they aren’t as silly as everyone has said. So, what did researchers do and what did they find?
A total of 42 undergraduate students participated in the simple study which basically had the participants snack on crackers while watching a sitcom…
Half of the participants were given one large 400-calorie package of crackers or a similar-sized package that had then been sub-divided into four smaller 100-calorie sub-packaged crackers. They were blinded to the purpose of the study.
After watching the show, the crackers not consumed by the participants were counted to calculate everyone’s caloric intake. Also, each participant was asked how many crackers they think they consumed.
Turns out, overweight participants ate significantly more crackers when eating from one large package than from four small packages. In fact, they consumed more than double the number of calories with the bigger package: 384 calories versus 176 calories.
Surprisingly, there was no difference in consumption between package conditions among the normal-weight participants.
Interestingly, the researchers found that only the overweight subjects were susceptible to unit bias! This is a really cool finding and it offers us a new contribution to overweight & obesity.
Research I’d like to see next is whether or not eduction of proper portion sizes can help overcome unit bias. Another possibility is that changing your environment so that your home is stocked with smaller bowls or plates could lead to a spontaneous reduction in calorie intake.