Free online Stroop test โ name the ink color, not the word, in 20 trials and get a "brain age" plus a global ranking
What is the Stroop effect?
In 1935 psychologist John Ridley Stroop showed that when the word RED is printed in blue ink, people are slower and make more errors naming the color than when the word and color match. Reading is automatic, so the meaning of the word interferes with the color-naming task. The size of that delay โ the Stroop effect โ is one of the most widely used measures of selective attention and cognitive control, used in clinical neuropsychology, ADHD assessment and brain-training apps alike.
In cognitive-science terms it is the textbook task for selective attention and inhibitory control: you must pick out the one relevant feature (ink color) and suppress the response that comes automatically (reading the word). On congruent trials, where word and ink agree, reading actually helps; on incongruent trials it gets in the way. This app mixes the two half and half and times all 20 trials in one go, so your result blends raw color-judgement speed with the ability to override interference.
How to play
- Press START. The first word appears at once and the timer begins โ a single stopwatch that never pauses during the 20 trials.
- A large word is shown in the middle. Ignore its meaning and look at its ink color, then tap the matching button below. Each button shows a color swatch, the color name and a number.
- On a keyboard you can answer with the 1ยท2ยท3ยท4 keys, in the same order as the buttons.
- A correct answer moves straight to the next word. A wrong one turns the button red for 0.22 s and adds one to the Wrong counter; the trial stays on screen until you pick the right color.
- Answer the 20th word correctly and the clock stops; 0.5 s later the result screen shows your brain age, raw time, wrong count and penalized score.
How this Stroop test works
- The words Red, Blue, Green and Yellow appear in a random ink color. About half of the trials are incongruent (word โ color).
- Tap the button (or press 1โ4 on a keyboard) that matches the ink color. A wrong answer adds a 1-second penalty.
- Your score is the total time for 20 trials plus penalties; that time is what the global leaderboard ranks.
- The brain age maps your average response time per trial onto typical reaction-speed trends by age. It is for fun, not a diagnosis.
| Trials | 20, using four colors: red, blue, green, yellow |
|---|---|
| Answer buttons | Always in the order red, blue, green, yellow; keys 1โ4 follow the same order |
| Incongruent share | Each trial has a 50% chance that word and ink differ |
| Wrong answer | +1 s penalty, 0.22 s input lock, and you must re-answer the same trial to proceed |
| Score (ranking) | Total time for 20 trials + 1 s ร wrong answers, to a tenth of a second. Lower ranks higher; ties share the same rank |
| Brain age formula | Average time per trial (raw time รท 20): 0.6 s = age 20, +1 year for every extra 0.02 s. Clamped to 12โ85 |
| Result message | Age 20 or under "sharp as a tack", 21โ30 "great focus", 31โ45 "about average", 46 and over "coffee break, then try again?" |
For example, finishing 20 trials in 16.0 s is 0.8 s per trial, which maps to a brain age of 30; 12.0 s (0.6 s per trial) gives 20, and 22.0 s (1.1 s per trial) gives 45. The brain age does not include the 1-second penalties, but the time you spend re-answering after a mistake stays on the stopwatch, so wrong answers still push your age up. The leaderboard score, by contrast, adds the full 1 s per mistake.
Tips to score younger
Don't fight the word โ that only slows you down. Instead, focus on the edge of the letters or a single stroke and name its color. Keep your mouth shut (subvocalizing the word makes the interference worse), and let your fingers learn the button positions so the last ten trials go faster than the first ten. Play a couple of warm-up rounds before going for a record.
- Certainty beats speed. A mistake costs the 1 s penalty plus the 0.22 s lock plus the time to answer again โ well over 1.5 s in practice. A hasty, unsure tap is the most expensive move in the game.
- Use the keyboard on a computer. The 1โ4 keys remove mouse travel entirely.
Frequently asked questions
My brain age came out as 12 or 85
Those are the floor and ceiling of the formula. An average of 0.44 s per trial or faster always shows 12; 1.9 s or slower always shows 85.
Is the leaderboard sorted by brain age?
No โ it ranks the total time in seconds including penalties. Brain age appears on the result screen and in the share message.
What if I am color-blind?
The four colors were chosen to be far apart, but red-green color vision deficiency can make red and green slower to tell apart. You may want to run the color vision test first.
How do I compare with a friend?
The share link carries your brain age and time. When a friend opens it, the title screen shows "Your friend's brain age is n" and challenges them to score younger.
Related tools
Compare your result with friends by sharing a link โ they see your brain age and get a "beat it" challenge. Then try the reaction time test, the Schulte table for attention, or the digit span memory test.
- Reaction Time Test โ pure reaction speed with no interference; the gap between it and your Stroop time is what interference costs you.
- Schulte Table โ the opposite drill: spreading attention wide instead of suppressing it.
- N-back Test โ a working-memory updating task where weak inhibition shows up as false alarms.
- Color Vision Test โ check that telling the colors apart is not the bottleneck.