I knew I was going to blog about this study before I was even done with the abstract. I suspect that it will be one of those things that once you hear it, it makes total sense - but you never really thought about it before.
This study had an interesting approach. There are four studies, but the method is about the same in each and I am only going to cover the first one. They created a fake restaurant menu and put a daily special on the front. In every case, the picture, the description, and the list of ingredients of the daily special were exactly the same and it was made up of pasta, vegetables, and dressing. The only thing different was the title. Half of the people saw it labeled as “Daily Pasta Special” and half saw it as “Daily Salad Special.” Then they tested it on people who were either dieting or not dieting. And they had respondents rate the special for how healthy they thought it was and how good it would taste.
First the non-dieters. They didn’t seem to care what it was called. Non-dieters who saw the “salad” rated it the same on expected healthfulness and expected taste as non-dieters who saw the “pasta” (a little more healthy, but not statistically significant). Apparently, non-dieters don’t really care about ingredients or titles, they just select what they want. The follow-up studies confirm this explanation.
The dieters who saw the “salad” special rated its expected healthfulness and taste the same as the non-dieters did. So they don’t look at healthy items as extra special (a positive attitude). But the dieters who saw the “pasta” special rated it less healthy and less tasty. They turned this into a negative experience. So it wasn’t that dieters are happy to get a salad or overconfident that the salad is healthier. It was that when they saw the “pasta” special, they got a negative bias – expecting it to be less healthful and less tasty. So when dieters look at a menu, they aren't happy that there are healthful options, they are unhappy at the unhealthful options, even if they don't have to order one.
In general, negative biases like this lead you to avoid the option, have increased mental workload, more stress, and be less happy overall. So if the dieters around you are unhappy, it isn’t because they are always hungry, it is because they look at the world with a negative frame.