Stumping Stroop


Stumping Stroop

By Adventure Science Center

Ready to work out your brain? Can you name a color and read a color? What if the word and the font color are different? Discover more about how the brain works to process information quickly with this tricky task!


Middle Tennessee native John Ridley Stroop’s research focused on measuring mental processes involving naming objects as well as reading object names. He developed a color-word task to demonstrate the interference between reading an object’s name and naming an object, and explained some of its psychological effects – which is now known as the “Stroop Effect!”


  • 10 3×5 index cards
  • Scissors
  • Ruler (optional)
  • Colored markers of five colors (should be distinctly different, such as green, brown, blue, red and yellow)
  • Timer or stopwatch
  • Volunteers


  1. Hold an index card vertically and cut across it twice to make three smaller cards, each about three inches by 1.6 inches. Do this to all 10 index cards so you end up with 30 cards.
  2. On 15 of the small cards, use a colored marker to write the name the marker’s color on the card (i.e., write the word “blue” with the blue marker). Each card should only have ONE color with matching name on it. Create three cards for each of your five colors.
  3. On the remaining 15 cards, use the same colored markers but this time write a color name that is not the same as the marker’s color (i.e., write the word “blue” with the yellow marker). Again, make sure you use all five different color markers, and make sure you use each marker on three cards.
  4. Keep the two sets of cards separated.


  1. Get your first volunteer ready by explaining that they will be given a set of cards where each card contains a word written in colored ink and their task is to call out the ink color of each word as quickly as possible without making a mistake.
  2. When you are both ready, give one of the sets of small cards to the volunteer and time how long it takes the volunteer to name the colors in the card set.
  3. Next, give the volunteer the other set of small cards and again time how long it takes the volunteer to name the colors in this card set.
  4. Repeat this process with your other volunteers. For each one, switch which set you start them with.
  5. Overall, which set did volunteers take the longest amount of time to get through, the set where the words on the cards match the colors they’re written in or the set where the words and ink color don’t match? Why do you think this is?

Further Exploration

  • Try this activity again but this time use cards with words written on them in matching ink compared with cards that have color words written on them all in black ink.
    • Do you find a difference in how easily people can read the color words based on the whether they’re written in matching ink or only black ink?
  • Repeat this activity but this time have people look at the cards so that the words are upside down.
    • Is there still a Stroop effect when the cards are used this way?


Did you find that people could more quickly go through the set of cards with the words written in matching ink compared with words that were written in a different color ink?

The Stroop effect shows that when a color word is printed in the same color as the word, people can name the ink color more quickly compared with when a color word is printed with an ink color that is different from the word.

One explanation for the Stroop effect is called interference. When we are asked to name the color of the word instead of reading the word, somehow the automatic reading of the word interferes with naming the color of the word. This interference effect provides scientists with a measurable means to investigate how the brain works.




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