How the test works
- A colour word appears, printed in a coloured ink.
- Click the button for the ink colour, not the colour the word names. You can also press R, B, G or P.
- There are 20 words. About one in four matches its ink; the rest don't.
- Your score is your average time per word. A wrong answer adds a 1-second penalty.
What it measures
The Stroop effect, first described by John Ridley Stroop in 1935, shows how hard it is to ignore something your brain does automatically. Reading is so automatic that the word gets in the way of naming the ink, so you slow down or make mistakes. The test measures selective attention and how well you can block out distractions.
What is a good score?
| Score | Faster than about |
|---|---|
| 587 ms | 99% of people (top 1%) |
| 762 ms | 90% of people (top 10%) |
| 887 ms | 75% of people |
| 1050 ms | 50% of people (average) |
| 1243 ms | 25% of people |
Estimated from typical scores for this kind of test.
Tips to improve
- Focus on the colour of the letters and try to blur the word itself.
- Rest a finger on each colour button (or the R, B, G and P keys) so you don't have to search.
- Accuracy matters: a wrong answer costs a full second, more than hesitating.
- Try it in a language you can't read; the effect mostly disappears, which shows it's caused by reading.
Frequently asked questions
What is a good Stroop test score?
Around 1,050 ms per word is typical when clicking. Under 850 ms puts you in roughly the top 20%, and under 700 ms is in the top 5%.
What is the Stroop effect?
It's the delay in naming a colour when it's printed as a different colour word, such as the word RED printed in blue. Your brain reads the word automatically, and that clashes with naming the ink.
Can I use this Stroop test in class?
Yes. It's a popular psychology and science activity. Use the For teachers page to share it with your class, and compare results with matching and mismatching words.