Guide
How the Stroop Test Works
The Stroop test is one instruction repeated fast: name the colour of the ink, ignore the word. Here is the deal, the controls, the scoring, and what reaction time and interference actually mean.
Take the Stroop testThe objective
Name the ink, beat the clock
One colour word appears at a time — RED, BLUE, GREEN, YELLOW, PURPLE, or ORANGE — printed in one of those six inks. Your only job is to answer the colour of the ink. What the word spells is a distraction, and usually a deliberate one.
You have a fixed run — 30 seconds, 60 seconds, or two minutes — to answer as many words as you can. Correct answers score points scaled by how fast you responded; wrong answers score nothing and reset your streak.
The test is free, runs in the browser, and needs no account. Open the board to take it; use this guide for the mechanics and the meaning of the numbers.
Why it is hard
Reading is automatic; colour naming is not
For a fluent reader, recognising a word happens whether you want it to or not. Naming a colour is a slower, more deliberate act. When the word says one colour and the ink is another, the fast automatic response collides with the slow deliberate one, and your brain needs extra time to push the word aside.
That extra time — a fraction of a second per word — is the Stroop effect, first measured by John Ridley Stroop in 1935. This test turns it into a live score you can watch move as you practise.
Controls
Tap a colour or key 1–6
Both do the same thing. The keyboard is faster once the number-to-colour mapping is in your fingers.
Touch
Tap a colour
Six large colour buttons sit below the word. Tap the one that matches the ink. The buttons are labelled with the colour name and a number so the choice is never ambiguous on a phone.
Keyboard
Number keys 1–6
Keys 1 to 6 map to the buttons left to right: 1 red, 2 blue, 3 green, 4 yellow, 5 purple, 6 orange. Keeping your fingers on the keys is the fastest way to play. Space or Enter starts a run and plays again.
Everywhere
M to mute
Press M, or use the speaker button in the HUD, to toggle the synthesized answer, countdown, and finish sounds. Your choice is remembered on this device.
The loop
Four steps, then the numbers
Pick, read, answer, review — repeated until the timer stops.
- 1
Pick a run length
Choose a 30-second sprint, the 60-second standard run, or a two-minute deep test on the start screen. Every run uses the same six colours — red, blue, green, yellow, purple, and orange — so your scores are comparable across lengths.
- 2
Read the ink, not the word
A colour word appears in the centre of the card, printed in one of the six inks. Your job is to answer the colour of the ink and ignore what the word actually says. When the word "GREEN" is printed in red, the answer is red.
- 3
Answer as fast as you can
Tap the matching colour button, or press its number key 1–6 on a keyboard. The moment you answer, the next word appears. A correct answer adds points scaled by how quickly you responded; a wrong answer scores nothing and resets your streak.
- 4
Read your results
When the clock hits zero you get your score, accuracy, mean reaction time, longest streak, and Stroop interference — the extra milliseconds the incongruent words cost you compared with the matching ones. Every run is saved to this device so you can watch the trend.
Rules & scoring
Every rule that moves your score
The objective
Score as many points as possible before the timer runs out by naming the ink colour of each word. Points per correct answer scale with your reaction speed and grow with your current streak.
Answering
Each word stays on screen until you answer. There is no skip and no penalty clock — a wrong answer simply scores zero and breaks your streak, then the next word appears immediately.
The colour set
Six inks are in play the whole run: red, blue, green, yellow, purple, and orange. Roughly seven in ten words are incongruent (ink and word disagree); the rest are congruent and give you a clean baseline.
Scoring
A correct answer is worth a base of 20 points plus a speed bonus that fades as reaction time rises, multiplied by a streak bonus that steps up every five correct answers in a row. Wrong answers and unanswered trials score nothing.
Results and interference
At the end you see score, accuracy, mean reaction time over correct answers, longest streak, and interference: mean incongruent reaction time minus mean congruent reaction time. A smaller interference number means you filter the distracting word more effectively.
Trial types
Congruent versus incongruent
Both types appear in every run — roughly 30% congruent, 70% incongruent. The gap between your reaction times on the two is your interference score.
- 01 · Word and ink match
Congruent
The word "BLUE" printed in blue ink. There is no conflict between reading and colour naming, so these trials are quick and act as your personal baseline reaction time.
- 02 · Word and ink disagree
Incongruent
The word "BLUE" printed in red ink. Your brain reads the word automatically and you have to override it to name the ink. These trials are slower and more error-prone — the gap between the two is the Stroop effect.
Common mistakes
Where good runs fall apart
Reading the word first
The natural instinct is to read the word and then correct yourself. That double step is exactly what the test is measuring. Train yourself to look for the colour of the strokes before your inner voice finishes the word.
Chasing speed past your accuracy
Answering faster than you can actually discriminate the colour just trades points for errors, and every error resets your streak multiplier. Find the pace where you are still near 100% correct, then nudge it.
Comparing different run lengths
A 30-second sprint and a two-minute run produce different fatigue and rhythm. If you want to know whether you improved, repeat the same length under similar conditions.
Reading one result as a diagnosis
Time of day, caffeine, sleep, and screen all move your numbers. The Stroop effect is a normal feature of every healthy brain. Use the trend across many runs, not a single score, and never treat it as a medical assessment.
- Fix your eyes on the centre of the card before the countdown ends so the first word does not surprise you.
- Rest your fingers on the 1–6 keys (or hover your thumb over the buttons) so answering is one motion, not two.
- Name the colour silently — "red", "blue" — instead of trying to not-read the word. Suppression is slower than substitution.
- Keep a steady rhythm. Rushing one answer usually costs you the next two in mistakes.
- If you slip, let it go instantly. Dwelling on a wrong answer is what turns one error into a broken streak.
- Take the same run length each time. Reaction time and interference only mean something when you compare like with like.
- Check your interference score, not just accuracy. Two people can both score 95% and have very different Stroop costs.
Where you can play
Same test on phone and desktop
strooptest.app runs in any modern browser with no app to install. History stays on the device you used.
Desktop browsers
Chrome, Edge, Firefox, and Safari all run the test with no plugin. The 1–6 number keys give the cleanest reaction times; Space starts and restarts a run, and M mutes.
Phones and tablets
The layout is touch-first. The word card and all six colour buttons stay on one portrait screen with no scrolling, and a new run starts instantly without a page reload.
History on this device
Your best score, best accuracy, fastest mean reaction time, longest streak, lowest interference, and the last twelve runs are stored in local browser storage. They stay until you reset them or clear site data, and they never sync to a server.
Still unsure about a term? Read the Stroop test FAQ or just take a run.
Take the Stroop test free