🎨Stroop Test

About this tool

Press Start and colour words appear one at a time, such as RED printed in blue ink. Click the button for the ink colour, or press 1 to 4, as quickly and accurately as you can. After 24 trials you see your median time on matching and clashing words, the difference between them, which is your Stroop effect, and your accuracy.

What the Stroop test measures

In 1935 the American psychologist J. Ridley Stroop showed that people are slower to name the colour of the ink a word is printed in when the word itself names a different colour. Reading is so automatic for practised readers that the word's meaning interferes with naming the ink, even when you try to ignore it. The Stroop task has since become one of the best-known experiments in psychology, used to study attention, cognitive control and processing speed. This version mixes congruent trials, where the word matches its ink, with incongruent trials, where they clash, in equal numbers and random order. Your Stroop effect is your median response time on incongruent trials minus your median on congruent trials; medians are used because they're less affected by an occasional slow response. Typical adults are about 50 to 150 milliseconds slower on clashing words, and errors are more common on them too. Practice, sleep, focus and even the device you use change results, so compare your own scores over time rather than with other people. Honest limits: this is an educational demonstration, not a clinical or diagnostic test of attention or any condition, and people with colour vision deficiency may find some ink colours harder to tell apart. The reaction time test measures simple reactions and the colour blindness test screens colour vision.

Frequently asked questions