Can you beat the Stroop effect?
The word says one color. The ink says another. Tap the ink, ignore the word, twenty times. Psychology has used this exact trap since 1935.
Tap the color of the ink. Ignore what the word says.
Green written in blue ink? The answer is blue. 20 cards.
Why this is hard, and what the score is worth
The effect is real and it is nearly ninety years old. Naming the ink while the word says something else takes measurably longer than naming either on its own. It was first shown in 1935 and has held up ever since, which is why it still turns up in attention research and in clinics. Stroop, Journal of Experimental Psychology, 1935.
The half nobody quotes: there are no published norms for a twenty-card version played on a phone. The bands above are our own thresholds on our own task, not percentiles from a population, and we would rather say that than dress them up. What the test is good for is the pull you feel and your own score across weeks. What it cannot do is tell you whether your attention is normal for your age.
Every figure on this site names where it came from. How we check.
Common questions
What is the Stroop effect?
When the word GREEN is printed in blue ink, reading the word is automatic and naming the ink takes deliberate effort, so almost everyone slows down and makes the odd slip. Psychologists have used this interference since 1935 to measure selective attention, and it remains one of the most replicated findings in the field.
What is a good score?
Getting 17 or more of the 20 cards right is solid, and 19 or 20 with under a second per card is sharp. The mismatched cards should feel harder; that pull between word and ink is the whole point, not a flaw in you.
Why is my focus so bad some days?
Attention runs on sleep and settles with practice at doing one thing at a time. Short nights, stress, pain, alcohol the evening before and constant phone-checking all measurably worsen it. A scattered score after a bad night is expected, not alarming; retry after a quiet day.
When is poor concentration worth a doctor visit?
When it is a lasting change from your own normal and shows up across life, not just on a screen test: unfinished tasks that used to be easy, rereading the same page, conversations that will not stick. Thyroid problems, depression, anxiety, sleep apnea, menopause and some medicines are all common, fixable causes a doctor can check.
Why is naming the ink color so hard?
Because reading is automatic and color-naming is not, so the word barges in ahead of the ink. Suppressing that reflex uses the brain's attention control, which is exactly why the Stroop task has been a lab standard for nearly a century. Slower, effortful, mistake-prone rounds after a bad night are normal; the trend across good days is the interesting part.