Today’s Wonder of the Day was inspired by Henry. Henry Wonders, “Do red and yellow actually make you hungry?” Thanks for WONDERing with us, Henry!

Are you hungry right now? If it's been awhile since breakfast or lunch, you might be thinking that a snack would hit the spot about now. If you're like most kids, you'll also be searching for an after-school snack the minute you arrive home after school.

Even if your body doesn't actually need food, you might still feel hungry at certain times. Have you ever felt hungry even you know it hasn't been that long since you last ate?

For example, a television commercial with a picture of a steaming-hot pizza fresh out of the oven might make your mouth water. Likewise, smelling popcorn upon walking into a movie theater can make you hungry even if you just ate.

What if you're riding in the car on the way home from school or soccer practice? Does the sight of fast food restaurant signs make you hungry for a cheeseburger, some French fries, or a slice of pizza?

Think about some of the signs for the most popular fast food restaurants. What do the signs for McDonald's, Wendy's, Burger King, Dairy Queen, and Pizza Hut have in common? They all make prominent use of two colors: red and yellow.

Could it be that these colors — red and yellow — make you hungry and want to stop for fast food? Although it might sound crazy, that's exactly what some scientists believe. The idea even has a name: the ketchup and mustard theory.

Scientists who study psychology believe that colors have certain effects on our feelings and emotions. They also point out that studies show that color gets communicated to the brain faster than any other type of communication.

For example, experts believe that the color red elicits feelings of warmth, comfort, and love. Likewise, yellow elicits feelings of happiness, excitement, and cheer.

Researchers believe that these colors, especially when used on fast food restaurant signs, create the perfect combination of emotions and feelings to make us feel hungry and want to stop to eat.

Critics of the ketchup and mustard theory, however, point out that there isn't enough scientific data to support the theory. They claim that feelings of happiness, excitement, and stimulation associated with the colors red and yellow don't necessarily equate to hunger.

While the science of colors and their exact effect on us may be unsettled, it's clear that fast food restaurants believe that there's some benefit to including red and yellow on their signs. Do these colors make us hungry? Maybe…or perhaps it's our own happy memories of delicious cheeseburgers, salty French fries, ice-cold sodas, and ice cream cones that keep us coming back for more!

Wonder What's Next?

Tomorrow’s Wonder of the Day will teach you not to fight fire with fire!