Stroop task

Name the ink color, not the word. That is the whole task — and it is harder than it sounds. When a color word is printed in a mismatched ink color (the word GREEN shown in red), people are much slower and make more errors naming the ink color than when naming the color of a neutral patch. In Stroop's original 1935 study this cost was about 74 percent extra time, and the effect has been reproduced in hundreds of studies over 90 years.Convergent / replicated Run the two short blocks above and compare your own times.

The interference runs almost entirely one way: the word disrupts naming the ink color, but the ink color barely slows reading the word aloud. This fits the long-standing observation that, for practiced readers, reading is so automatic that it cannot simply be switched off on request, so the word's meaning arrives whether you want it or not.Convergent / replicated What you feel as a small mental stumble is two well-practiced processes reaching for your voice at once.

The demonstration shows that a highly practiced skill can run off involuntarily and intrude on what you are deliberately trying to do — and that this intrusion is shaped by experience. Stroop himself found that eight days of practice at color naming reduced but did not abolish the interference, and later training studies and computational models show interference tracks the relative strength of the two competing processes rather than being all-or-none.Supported, with limits

This browser version is a demonstration, not a test of you: it has no normative data and cannot diagnose attention problems or anything else. Even under controlled lab conditions, Stroop difference scores rank individuals only modestly reliably from one session to the next, and a web browser adds further noise from device and browser timing differences — on top of the fact that scores change with simple practice.Supported, with limits Clinical Stroop instruments exist, with norms and controlled administration; this page is deliberately not one.

Although the effect itself is rock-solid, why it happens is still debated. The two classic explanations — "words are simply read faster than colors are named" and "reading is automatic" — were both judged inadequate in their simple forms by the major 1991 review, and several competing modern models (pathway-strength, perceptual, and language-production accounts) each reproduce the main findings without a consensus winner.Mixed / contested

A separate caveat for this demo: Stroop's original magnitudes come from timed 100-item cards, not per-trial reaction times, so his "74 percent" does not translate directly into the millisecond differences a browser session shows. Be clear about what the quiet mode is, too: neither mode here puts you under a time limit, and the task is the same either way. Quiet mode only hides the millisecond readout, so the page cannot start reading like a measurement of you — a gentler presentation, not a different experiment, and in neither case something we would call experimentally identical to a laboratory Stroop.