How it works
- A cross appears in the middle of the card. Look at it.
- A word appears: RED, GREEN, BLUE or YELLOW, printed in one of those four inks.
- Press the swatch of the ink color as fast as you can, and ignore what the word says. On a keyboard, use D, F, J and K, shown under the swatches.
- Eight practice trials tell you whether you were right. The 40 timed trials don’t.
Half the trials match (RED in red ink) and half don’t (RED in blue ink). Each word disappears after 2.5 seconds. Answers under 0.2 seconds are too soon to have seen the ink, so they don’t count.
What the numbers mean
Your Stroop effect is your median time on mismatched words minus your median time on matching words, using correct answers only. It’s the extra time it takes to name the ink when the word says another color. Reading is so automatic that the word gets in the way even when you try to ignore it.
The effect is named after J. Ridley Stroop, who published the experiment in 1935. Reaction times depend on your device as well as on you: a phone screen, a keyboard and a mouse each add their own delay. Results are kept apart for each kind of input, and only compared with your own.
If fewer than 70% of your answers are correct, or more than 1 in 5 come too soon, the result is marked unreliable. It’s saved in your history but never counts as a best.
If you switch tabs or windows during the timed trials, the test stops and nothing is saved: a pause would change the times.
Keyboard
D, F, J and K answer with the swatches in that order, left to right. Rest two fingers of each hand on them before you start.
Your results
Results stay in this browser. Nothing is sent anywhere. For fun and self-tracking: this is not a medical or diagnostic test.
More to play
- El Word: One hidden word a day. Six guesses to find it.
- All brain tests
- El Trivia home