Key concepts
The brain

Have you ever tried adding green food coloring to your milk? Or blue coloring to the butter you spread on your bread? You might not have tried this, but for years scientists have been studying the effect of color and food appearance on how we perceive food tastes. Believe it or not our eyes are an important part of tasting and perceiving food! In this activity you will learn about how you can trick your taste buds—with just a little food coloring!

The taste buds on your tongue detect flavors and help you identify the foods you eat. Other senses, however, also play a role in how we experience our foods. You probably know the aroma of foods can have a strong effect on how they taste, but did you know the appearance of food also changes how we experience it? Because we usually look at food before putting it in our mouths the very first information your brain gets about any particular food often comes from the eyes!

From an early age we learn to associate colors with flavors. When something is orange, we expect an “orange” flavor. If you tasted orange pudding, you would be surprised to find it had a mint flavor. Discrepancies between the appearance of foods and their tastes can make it more difficult to identify the flavoring.

Research has shown the appearance of food can dramatically affect how it tastes to us. In one study participants ate a plate of normal-looking steak and French fries. All the participants said they enjoyed the food, and it tasted fine. When the lights were brightened, however, it was revealed that the steak was dyed a blue color, and the fries were green. When they saw this many of the participants refused to eat any more of the food—and a few even became sick.

In this activity you will be exploring how the appearance of the food we eat affects how it tastes. Don’t worry, there won’t be any blue meat!


  • At least three volunteers
  • Large bottle of apple juice
  • Blue, green and red food coloring
  • At least nine clear disposable cups (three for each volunteer)
  • Permanent marker
  • Piece of paper
  • Pen or pencil
  • Three regular water glasses
  • Water
  • Table where you and your volunteers can sit
  • Timer or stopwatch


  • Prepare the drinks ahead of time. It’s important that your volunteers don’t know that there is apple juice in each cup! The idea is that your volunteer should expect something different in each cup. Therefore, don’t let them see you preparing the drinks.
  • Use your marker to number the clear cups. Label three of the cups with the letter “A,” three cups “B” and the remaining ones “C.” (That will give you three cups for each volunteer.)
  • Add one-quarter cup of apple juice to each clear cup.
  • Line up in rows all the cups labeled A; all those labeled B; and all the C cups.
  • Add at least two drops of blue food coloring to the A cups. (If necessary, with this and the other colors add more to darken.)
  • Add two drops of green coloring to the B cups.
  • Add two drops of red coloring to the C cups.
  • What color do you think will be volunteers' favorite? What about their least favorite? Why?
  • Use your pen and paper to make a chart with five columns (or two more than the number of volunteers that you have) and four rows. Label the first column, “Letter on Cup”; the second column, “Volunteer 1”; the third column, “Volunteer 2,” etcetera; and the final column, “Total.” Label the second row, “A”; the third row, “B”; and the fourth row, “C.”
  • Fill the three drinking glasses with water.


  • Have your first volunteer sit down at the table. Line up one of each cups labeled A, B and C in front of your volunteer. Also give them a glass of water.
  • Ask them to start by drinking some water as a palate cleanser.
  • Tell your volunteer you want them to taste the drink in cups A, B and C, drinking water in between each. They have two minutes total to taste the drinks. Once they’ve tasted the drink in each cup, they should rate them from the one they liked the best to the one the liked the least. Your volunteer can taste each cup more than once, but should drink water in between each taste. Let your volunteer know you cannot provide any information about what is in the cups or respond to during the sampling.
  • Have your volunteer start the test. As they taste their first cup, start your timer or stopwatch. Remember to not answer any questions or react to anything your volunteer says!
  • After two minutes stop your timer and tell your volunteer to stop tasting.
  • Ask which drink was their favorite. In the Volunteer 1 column mark their favorite cup with the number 3. If your volunteer said the cup B drink was best, for example, you would write number 3 in the B row under Volunteer 1.
  • Ask your volunteer which drink they liked least. In the Volunteer 1 column record their least favorite cup with the number 1.
  • Write the number 2 in the remaining row.
  • Repeat these steps with your remaining volunteers. Record their responses in the corresponding columns.
  • Add the values across each row and record the totals in the Total column. If Volunteer 1 gave a 2 rating to cup A, Volunteer 2 rated cup A a 1 and Volunteer 3 rated cup A a 2, you would record 5 in the Total column for cup A. Which cup has the highest total? Which has the lowest? Were there any patterns in which cup the volunteers seemed to prefer? Did these match your expectations?
  • Extra: At the end of the activity have your volunteers close their eyes and taste the juice in each cup again. Do they notice a difference in how the juice tastes, compared with when their eyes are open?

Observations and results
In this activity you tested whether the color of a liquid impacted your volunteer’s perception of the liquid’s taste. Despite the fact each cup contained the same thing (apple juice), you probably found your volunteers preferred the taste of the juice one of the cups over the other. Because the only difference between the liquids was the color, we can determine from this activity that the appearance of the liquid affects how it tastes.

If any of your volunteers noticed the cups all contained the same thing—compliment them on their acute taste perception! We rely so heavily on visual information, it often influences how we perceive information coming from our other senses. If any of your volunteers were able to separate the visual information from what they were tasting, their perceptions are especially sharp!

More to explore
Battle of the Senses: Taste versus Smell, from Science Buddies
Do You Love the Taste of Food? Find Out If You’re a Supertaster!, from Science Buddies
Sensory Science: Testing Taste Thresholds, from Scientific American
STEM Activities for Kids, from Science Buddies

This activity brought to you in partnership with Science Buddies

Science Buddies