Speed game
Color Clash — the Stroop test, free online
The word says RED, the ink says blue — and your brain wants to shout the wrong answer. Tap the ink color, not the word, and feel one of psychology's most famous effects fight you in real time.
Free to play, no sign-up. Want to track your progress across six skills? The Axolumi app is coming to Google Play.
How to play Color Clash
- A color word appears on screen, printed in colored ink — usually a color that disagrees with the word.
- Tap the answer button that matches the INK color, not what the word says.
- Every button shows a color swatch and its name, so you never have to judge by color alone.
- A wrong tap costs 2 seconds and resets your streak, so a beat of care beats a fast guess.
- On Hard and Extreme, the rule itself flips between 'tap the INK' and 'tap the WORD' — keep one eye on the banner.
What Color Clash trains
- Focus · 50%
- Speed · 30%
- Reading · 20%
Color Clash is built on the Stroop effect, first documented by John Ridley Stroop in 1935 and still a standard tool in attention research today. Reading is so automatic for a fluent reader that the word's meaning arrives before you can stop it — so when the word RED shows up in green ink, two answers race for your attention and only one is right. Suppressing the automatic response in favor of the instructed one exercises inhibitory control, a core piece of what psychologists call executive function.
The harder levels add cognitive flexibility on top. When the rule flips from 'tap the ink' to 'tap the word', the response you just spent twenty trials suppressing suddenly becomes the correct one. Switching between competing rules without missing a beat is task-switching in its purest form — and the time pressure keeps your processing speed honest throughout.
Tips to improve
- Soften your focus. The less sharply you read the word, the weaker its interference — some players fix their eyes on the first letter only.
- Say the ink color in your head before your finger moves. Naming it silently helps override the word.
- After a rule flip, deliberately slow down for one or two trials. The old rule lingers, and that is when errors cluster.
- Congruent trials — where word and ink agree — are gifts. Bank them quickly, but don't let them lull you into reading again.
Frequently asked questions
The Stroop effect is the delay you experience when naming the ink color of a word that spells a different color — for example, the word RED printed in blue. It was described by John Ridley Stroop in 1935 and is one of the most replicated findings in psychology. Because reading is automatic, the word's meaning interferes with naming the ink, and your response slows down or slips.
Because you are pitting a deliberate task against an automatic one. Fluent readers cannot choose not to read — the word's meaning arrives instantly and for free, while identifying the ink color takes deliberate attention. On incongruent trials the two answers conflict, and suppressing the automatic one takes measurable extra time and effort.
Chiefly inhibitory control — the ability to suppress an automatic response in favor of an instructed one — along with selective attention and processing speed. Researchers use the gap between your speed on matching and mismatching trials as a signal of cognitive interference. Versions with rule switches, like our harder levels, also probe cognitive flexibility.
Easy uses 4 colors with about half the trials congruent, so you can settle into the task. Medium moves to 5 colors and makes nearly every trial a mismatch. On Hard, the rule flips between 'tap the INK' and 'tap the WORD' every few rounds. Extreme flips the rule mid-stream with 6 colors in play.
We designed for it. The palette is chosen to stay distinguishable across common types of color blindness, and every answer button carries the color's name next to its swatch — you never have to rely on hue alone. If two inks still feel close on your screen, the labels always give you a reliable path to the right answer.
