Optical Illusions Can Trick Your Eyes And Your Appetite

In 2011, the USDA replaced the infamous Food Pyramid, with a simpler new icon, MyPlate. Designed to remind Americans about healthier eating habits, it suggests that half of your plate should be filled with colorful fruits and vegetables. Whole grains and lean protein should fill the other half, with a cup of low-fat dairy on the side.

The plate symbolically represents a meal, Delboeuf illusiongenerosity and nourishment, but you may not realize that your choice in dishware can affect what we eat and how much. We make many choices subconsciously, with hard-wired responses to aromas, the company we’re in and visual cues. Our eyes are easily misled, and this can have a big impact on our diets.

There’s an old saying, “The first bite is with your eyes.” Authors and professors Brian Wansink, of Cornell’s Food and Brand Lab, and Koert van Ittersum, of Georgia Tech’s Marketing department, found this to be very true. They explored how an optical illusion first documented in 1865 leads us astray with inaccurate estimates of serving size, depending on what size plate they are presented on.

The Delboeuf illusion [see image] has long been known to cause us to misjudge the size of identical circles when they are surrounded by larger circles of varying sizes. The more “white space” around the circle, the smaller it appears.

The professors found that the same applies to the dishes we use every day. Larger plates can make a serving of food appear smaller, and smaller plates can lead us to misjudge that very same quantity of food as being significantly larger. Restaurants are very aware of this, and you will often see different entrees served on plates customized for presentation of that dish. Diners expect to see supersized portions, and plate size matters.

In research conducted at a health and fitness camp, campers who were given larger bowls served and ate 16% more cereal than those given smaller bowls. To make matters worse, they underestimated what they ate, as estimates of their cereal consumption were 7% lower than the estimates of the group eating from the smaller bowls.

A study conducted in a real-world buffet line showed that when asked to shoot for a specific serving size of soup, people underserved and overestimated by 12% when they had a smaller soup bowl, but with a larger bowl, participants overshot the target by 13%. This happened even if the study group was taught about the optical illusion beforehand!

There are other illusions that even experienced bartenders can’t overcome. A pour looks a lot more voluminous in a tall, thin glass versus a short, wide glass.

This may affect your family barbeque as well. Hamburger patties that were flattened out and appeared larger were rated as more satisfying, despite the fact that the serving size was the same.

Visual placement is another factor influencing our eating behavior. People who keep a bowl of fruit on the counter, or cut veggies at eye level in the fridge, tend to eat more fruits and vegetables. In a hospital cafeteria, sales of water and other low-calorie beverages jumped when they were placed at eye level.

At the same hospital, a color-coding system of green (healthy), yellow (eat in moderation, with caution), and red (a less healthy option), dramatically improved sales of healthy choices.

So what can you do at home?
1.    Use smaller plates overall, but in particular when serving calorie dense foods. You’ll be more satisfied with a smaller portion.
2.    Stock up on tall, thin glasses. Now is the time for iced tea or water lightly infused with a few slices of cucumber and orange.
3.    Cook colorfully. Meals that are uniform in color tend to be less filling. Vibrantly colored foods served side by side gives the appearance of increased quantity.
4.    Consider blue plates. Since blue is not a color that naturally occurs in our food, it seems to tame the appetite.
5.    Beware of food porn. Watching the Food Network and reading cooking magazines may increase levels of the hormone ghrelin, which makes us hungrier and eat more.
6.    Eat mindfully. Ok, so this isn’t an optical illusion, but it’s really helpful. Since I grew up in a big family, then transitioned to eating on the run during medical school and residency, this is a big one for me to remember. Slow down and pay attention to your food and your stomach. This will help you enjoy and feel pleasure with your meal. Also, it helps you assess your level of fullness, so you can stop before you are stuffed.