Stroop Test

The Stroop effect was documented by psychologist John Ridley Stroop in 1935 and remains one of the most replicated findings in cognitive science. Reading is so automatic for literate adults that when the word GREEN appears printed in red ink, the word fights the colour for control of your response — and naming the ink takes measurably longer. That small delay reveals how much effort selective attention really takes.

This version gives you two ways to answer. In tap mode you press the button for the ink colour — the classic task, with four colours. In match mode you judge yes or no whether the word and its ink agree, with a six-colour pool and arrow-key shortcuts. Run it as a timed sprint of 30 to 120 seconds or race to a fixed number of correct answers, from 15 to 60. The score rewards speed and accuracy together, so mashing buttons with sloppy answers scores worse than steady precision.

After each run the tool splits your reaction times into congruent trials (the word matched its ink) and incongruent ones, and reports the difference in milliseconds — your personal Stroop interference, a direct measurement of how strongly automatic reading intrudes on your focus. Reaction times are captured with the browser's high-resolution timer, and the run ends automatically if you switch tabs, so results stay honest.