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Neuroscience For Kids

Colors, Colors

The famous "Stroop Effect" is named after J. Ridley Stroop who discovered this strange phenomenon in the 1930s. Here is your job: name the colors of the following words. Do NOT read the words...rather, say the color of the words. For example, if the word "BLUE" is printed in a red color, you should say "RED". Say the colors as fast as you can. It is not as easy as you might think!


Try this Interactive Stroop Effect Experiment. The computer will keep track of the time it takes you to say the colors of the words.

[Run Experiment]

Also available: print out Stroop Test Mini Cards.


The words themselves have a strong influence over your ability to say the color. The interference between the different information (what the words say and the color of the words) your brain receives causes a problem. There are two theories that may explain the Stroop effect:

  1. Speed of Processing Theory: the interference occurs because words are read faster than colors are named.
  2. Selective Attention Theory: the interference occurs because naming colors requires more attention than reading words.

I think that this puzzle would be easier for a very young child than for older children or adults. Try this out on some small kids who know their colors, but cannot yet read! I would imagine that the children would not get confused by this puzzle because the words would not have any meaning to them.

My scores: Test #1 = 10.1 seconds; Test #2 = 22.4 seconds
It took me more than TWICE the amount of time to read the "confusing" words.

There is some evidence that the anterior cingulate area is active in people during the Stroop effect.

More experiments to try:

The original reference to the Stroop paper is: Stroop, J.R. Studies of interference in serial verbal reactions. J. Exp. Psychol., 18:643-662, 1935. You can even read this complete 1935 paper on the web!

If you would like to use the Stroop Effect as an experiment in class, here is a lesson ready to go.

Other web resources on the Stroop effect:

  1. Interference - from the American Psychological Association
  2. Stroop Effect - from NOVA

New Stroop Tests

Here are three new variations of the Stroop Effect that you may not have seen.

  1. Try this Interactive DIRECTIONAL Stroop Effect Experiment. The computer will keep track of the time it takes you to say the LOCATION of the words.
    [Run Directional Stroop Experiment]
  2. Try this Interactive NUMBER Stroop Effect Experiment. The computer will keep track of the time it takes you to count the number of words. [This "Counting Stroop Effect" was described originally by Bush, G. et al., The counting Stroop: An interference task specialized for functional neuroimaging--validation study with functional MRI. Human Brain Mapping, 6:270-282, 1998.]
    [Run Number Stroop Experiment]
  3. Try this Interactive ANIMAL Stroop Effect Experiment. The computer will keep track of the time it takes you to say the NAME of animals you see.
    [Run Animal Stroop Experiment]
  4. Shape Stroop Test. Download the test papers. Try the test two ways. First, say what the word says and ignore the shape on each paper. Second, say what the shape is and try to ignore the word.

Are these new tests easier or harder than the original colored word Stroop Effect? Why?

Did you know?
Dr. Stroop left the laboratory not long after he published his studies on his "effect" and joined the faculty at David Lipscomb College, a small Christian college in Nashville, TN. He died in 1973 at the age of 76. Read more about "Brother Stroop" (that's what his students called him) in Science News, Vol. 141, pages 312-316, 1992. Also, read about the donation of Stroop's original thesis to Vanderbilt University.

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