About the Stroop test
What the test measures
Say the colour of the ink, not the word. Simple—until “red” shows up in blue and you stumble. That tiny hesitation is the Stroop effect: your brain reads the word whether you want it to or not, and it takes real effort to push that automatic reading aside. Stroop spotted this interference back in 1935, and it still works as a clean, quick measure of how well you can stay focused when something is pulling your attention the wrong way (MacLeod, 1991).
How this tool scores it
You’ll see three types of trial in equal numbers—word and ink agree, word and ink clash, or the word has nothing to do with colour. That even split is deliberate: if clashing trials turn up too often, people start bracing for them, and the effect quietly shrinks (Egner, 2007).
Your score is simply how much slower you are on clashing trials than on matching ones. Only correct answers count. The tool uses your median response time rather than the average, because a few slow outliers can pull a mean off course. It also trims anything faster than 200 ms (too fast to be a genuine decision) and anything more than three standard deviations from your own pace—a cutoff that gave the most stable results in Paulhus & Carey (2021).
The Chinese-character version
Chinese characters look more complex than English words, so you might expect them to cause more interference. They don’t—the effect is about the same size in both scripts (Chen, Cheung & Chui, 2000). The Chinese version is also highly consistent when the same person takes it again, with test–retest reliability of ICC 0.82–0.93 among older Taiwanese adults (Lin et al., 2018). It uses four everyday colour words—紅, 綠, 藍, 黃—all familiar and similar in stroke count, with non-colour characters as neutral stimuli.
References
- Stroop, J. R. (1935). Studies of interference in serial verbal reactions. J. Exp. Psychol., 18(6), 643–662.
- MacLeod, C. M. (1991). Half a century of research on the Stroop effect. Psychol. Bull., 109(2), 163–203.
- Chen, H.-C., Cheung, H., & Chui, H. L. (2000). Stroop interference in Chinese and English. Mem. Cognit., 28(5), 801–807.
- Lin, K.-H., et al. (2018). Reliability of the Chinese version of the Trail Making Test and Stroop. Int. J. Gerontol., 12(4), 336–339.
- Paulhus, D. L., & Carey, J. M. (2021). Comparison of response-time outlier exclusion methods. Front. Psychol., 12, 675558.
- Egner, T. (2007). Congruency sequence effects and cognitive control. Cogn. Affect. Behav. Neurosci., 7(4), 380–390.