Stroop Test — the free browser version of the classic colour–word experiment

The word on screen says GREEN. It is printed in red ink. Your job is to answer red — and for about a quarter of a second, your brain refuses. That delay is the Stroop effect, one of the most reliably reproduced findings in all of psychology, and this is a 45-second game built on it. Every correct answer is a point, every wrong one costs three seconds of your clock, and the run gets harder as you go: the palette widens from four colours to six, and past a certain score the question starts flipping between "the ink" and "the word" without warning.

No download, no account, nothing to install. It plays with a thumb on a phone or with the number keys on a desktop, and your best five runs are stored on your own device so there is always a target sitting on the menu.

How to play

• Read the prompt above the word: it says TAP THE INK COLOUR almost every time.
• Tap the button naming that colour. On a desktop, keys 1–4 map to the four buttons.
• Correct is +1 point. Wrong costs 3 seconds — guessing is worse than pausing.
• After 10 points the palette grows to six colours; after 18 the prompt sometimes flips to TAP THE WORD. Read it every time.

Why a word you aren't even trying to read still slows you down

For a literate adult, reading is automatic in the technical sense: it does not wait for permission. Show a fluent reader a word and the meaning arrives whether or not it was asked for, in roughly 200 milliseconds — faster than the same brain can name a colour patch, which takes closer to 350. So by the time your colour-naming system has an answer ready, a competing answer is already sitting in the response queue, and the extra 200–300 milliseconds you feel is the cost of throwing it out.

John Ridley Stroop published the effect in 1935, and it has held up for ninety years across languages, alphabets and screens. The details are revealing: the interference nearly vanishes if the word is upside down or in an unfamiliar script, because those break automatic reading — and it is much weaker in children who have just learned to read, then grows as their fluency does. In other words, this test punishes you for being good at reading.

Two things genuinely improve your score, and one popular tip doesn't. Defocusing your eyes helps: blur degrades letter shapes, which reading depends on, far more than it degrades a large block of colour. Looking slightly off the word helps for the same reason, since peripheral vision reads badly but sees colour fine. What does not work is trying harder to ignore the word — suppression is effortful, it is the thing that is already costing you the time, and pushing on it tends to slow you down further. The clinical version of this test is used as a measure of exactly that capacity, so treat your score as a fun proxy for it and nothing more: it is a browser game, not an assessment.

More games

More brain tests: Color Test, Verbal Memory, or the Reflex Test. Or browse all games.