Try this: name the colour a word is printed in, not the word itself. If the word RED is printed in blue ink, you should say "blue" — and you'll probably feel a tiny hitch before you do. That hitch is the Stroop effect: naming a colour is harder and slower when the word spells a different colour, because reading gets in the way.
🌈 Take the 60-second Stroop test →
The effect is named after John Ridley Stroop, who described it in a now-classic 1935 paper, Studies of interference in serial verbal reactions, published in the Journal of Experimental Psychology. He measured how much longer it took people to read colour words printed in a conflicting ink than in plain black — and that difference, the "interference," is the effect that carries his name. It has since become one of the most-used tasks in all of psychology: a simple, reliable way to reveal how automatic reading really is.
For anyone who reads fluently, reading is automatic. You don't decide to read the word "RED" — you just do, instantly, whether you want to or not. Naming the colour of the ink, by contrast, is a slower, more deliberate act.
When the word and the ink agree (the word RED printed in red), both responses point the same way and you're quick. When they conflict (RED printed in blue), the automatic reading response fights the colour you're trying to report. Your brain has to suppress the word and choose the colour — and that extra step of cognitive control costs measurable time and a few more mistakes. That cost is the Stroop effect.
Because it pits an automatic habit against a deliberate goal, the Stroop task is treated as a window into selective attention, processing speed and cognitive control (sometimes called inhibition). It's a standard tool in experimental psychology and in neuropsychological assessment, where clinicians use versions of it to probe attention and executive function. In everyday terms, it's a neat demonstration of how much of your mind runs on autopilot — and how much effort it takes to override it.
TAPSIXTY's Stroop test uses a quick match / no-match format. A colour word appears in a coloured font, and you decide as fast as you can whether the word means the colour it's shown in. Right answers build your score and your streak; wrong ones reset the streak. It's the same underlying conflict as the classic task, tuned into a sixty-second sprint — and you'll feel the interference most on the trials where word and colour disagree.
Two things separate a strong Stroop run: speed and accuracy under conflict. Anyone can go fast if they stop checking; the skill is staying fast and correct when the word is trying to trick you. A good score means lots of correct answers with few resets. If you find your accuracy dropping as you speed up, that's the effect doing exactly what it's famous for — ease off a touch and let control catch up.
🌈 Take the 60-second Stroop test →
The extra time and errors when you name the ink colour of a colour word that spells a different colour (e.g. RED printed in blue). Reading is automatic and interferes. Named after John Ridley Stroop (1935).
Reading is fast and automatic; colour-naming is slower and deliberate. When they conflict, your brain must suppress the word to report the colour, which takes extra time.
Selective attention, processing speed and cognitive control (inhibition). It's a standard task in psychology research and in neuropsychological assessment of executive function.
Focus on the colour, not the word; stay steady rather than frantic; and expect the first few trials to feel hardest.
Source. Stroop, J. R. (1935), "Studies of interference in serial verbal reactions," Journal of Experimental Psychology, 18(6), 643–662 (doi:10.1037/h0054651). The full text is in the public domain via York University's Classics in the History of Psychology archive.