Stroop Test

What Is the Stroop Effect?

The Stroop effect is the slowdown you feel when you try to name the ink color of a word that spells a different color — like the word RED printed in blue. You just felt it in the test above. Reading is so automatic that your brain reads the word before you can stop it, and that meaning competes with the color you're trying to report.

The gap between your matching-trial speed and your mismatching-trial speed is your Stroop interference. Almost everyone shows some — it's a normal sign that reading has become automatic. It was first described by John Ridley Stroop in 1935 and is one of the most reliably reproduced findings in psychology.

What the Stroop Test Measures

The Stroop test is a measure of selective attention and automatic versus controlled processing. Naming an ink color is a controlled task — you have to focus. Reading is automatic — it happens whether you want it to or not. When the two conflict, the automatic process intrudes, and the time cost is your interference score.

• Matching (congruent) trials: the word and ink agree, so reading helps — these are your fastest responses.
• Mismatching (incongruent) trials: the word and ink disagree, so reading fights you — these are slower.
• Interference: mismatching time minus matching time. A typical effect is roughly 50–200 ms, though it varies a lot by person, device, and how carefully you go.

The Stroop Effect in AP Psychology (Unit 2: Cognition)

In the redesigned AP Psychology course, the Stroop effect shows up in Unit 2: Cognition as the go-to example of selective attention and automatic processing. For the exam you should be able to explain why the interference happens — reading is automatic and competes with the controlled task of color naming — not just define it.

Running the test on yourself is the fastest way to lock that in: you don't memorize "automatic processing," you feel your own brain doing it. When you're ready to gauge where you stand on the whole exam, try the AP Psychology score calculator.

Stroop Test — FAQ

How do you take a Stroop test?

You're shown color words printed in colored ink and you identify the ink color, not the word, as fast as you can. The test compares your speed on matching trials with your speed on mismatching trials, and the difference is the Stroop effect.

What does a high Stroop interference score mean?

A larger interference score means reading slowed your color-naming more. That's normal and mostly reflects how automatic reading is for you, plus attention and focus in the moment. This is an educational demo, not a clinical or diagnostic test.

Is this Stroop test accurate?

It uses the standard congruent-versus-incongruent design, so the pattern it shows is real. Exact millisecond numbers depend on your device, browser, and how fast you tap, so compare your own matching and mismatching times rather than treating the raw numbers as lab-grade.