On this page
How the task works
Each item shows a colour word, such as red, blue or green, and the word itself is displayed in some ink colour. Your task is to choose the ink colour, not the meaning of the word. Several colour swatches appear below; tap the one that matches the colour the word is printed in.
Sometimes the word and the ink agree, such as "red" printed in red. These are congruent items. More often they disagree, such as "red" printed in green. These conflict items are the heart of the exercise.
How the levels change
- Level 1: eight items with no conflict, to learn the controls.
- Level 2: ten items, and conflict items begin to appear.
- Level 3: twelve items with congruent and conflict items mixed.
- Level 4: twelve items with a time limit and a countdown on each.
- Level 5: fourteen items with less time.
- Level 6: sixteen items at top speed.
From level 4 onwards, a correct answer earns base points plus a bonus that grows with the time you have left. Running out of time counts as a wrong answer.
Why the tug-of-war happens
For fluent readers, reading is almost automatic. When you see a word, its meaning pops up whether you want it or not. Naming the ink colour, by contrast, takes deliberate effort. When the two point to different answers, the automatic one gets there first, and you have to hold it back before giving the right answer.
This is known in psychology as the Stroop effect, and it has been used for decades in research on attention and inhibitory control. It illustrates an everyday truth: we often make mistakes not because we do not know the right answer but because our automatic response is too fast.
What it trains
Stroop practises the ability to pause before responding, usually grouped under inhibitory control. Daily life has many similar moments: waiting for someone to finish before you speak, resisting a notification you want to open, writing down an unrelated thing to look up later instead of searching for it mid-homework.
To be clear, holding back the urge to read a word in an exercise is not the same as holding back the urge to pick up your phone. Researchers hold different views on whether this kind of training carries over to everyday behaviour. We prefer to see it as a reminder: it lets you feel how fast automatic responses are and how much attention it takes to stop them.
Practical tips
- Look at the edges or strokes of the word. Some people find that not "reading" the centre of the word, and instead looking at its edges or overall block of colour, reduces interference from its meaning.
- Say the colour silently. When the word appears, say only the colour name in your head, for example "green", then find the swatch.
- Accuracy first, speed later. Mistakes on conflict items usually come from rushing. The first three levels are untimed, which makes them perfect for practising accuracy. Speed up gradually once you reach the timed levels.
- Learn the swatch positions. If the swatches stay in familiar places, knowing where they are saves search time and leaves more attention for judging the colour.
Reading your results
On the results screen, look at accuracy first and points second. Accuracy reflects how well you held back the automatic response on conflict items. In the timed levels, points also reflect your response speed.
If you notice you always make the same kind of mistake, such as tapping the colour the word names, that is the Stroop effect at work. There is no need to be discouraged; slow down a little.
When to practise
Stroop is short. One round takes a minute or two, which makes it a good fit for moments when you need to change state: after scrolling, before a meeting, or before a stretch of reading where you need to resist distractions. It rotates well with visual tasks such as Schulte and ball tracking, so you are not always practising the same ability.
Frequently asked questions
Can I practise if I have colour vision deficiency? Stroop depends on telling colours apart. If some colours are hard for you to distinguish, this task may not suit you, or your results may not reflect your attention. Consider Schulte, N-back or backward digit span instead, which do not rely on colour.
Do conflict items stay hard once I am used to them? With familiarity, many people become a bit faster and make fewer mistakes on conflict items, but the automatic pull of reading rarely disappears completely. That is what makes Stroop interesting: even when you know the rule, the automatic response still shows up, and each item asks you to tap the brakes.
Why do I sometimes get congruent items wrong? After several conflict items in a row, a sudden congruent item can make some people hesitate or even deliberately choose the other colour. Sticking to one rule, "only look at the ink", and not trying to guess the item type reduces this error.
Summary
Stroop has just one rule: look at the colour, not the word. That simple rule shows you the pull between automatic responses and deliberate control. Build accuracy on the untimed levels first, then speed up gradually on the timed ones, and slow down by half a beat when mistakes start to pile up. Place it at moments when you need to switch state; it only takes a minute or two, and you can carry the feeling of pausing first into whatever you do next.
A note on fairness and comfort
Stroop feels harder for some people than others, and that is fine. Reading fluency, screen brightness, colour perception and simple tiredness all play a role. If the timed levels feel stressful rather than challenging, stay on the untimed ones for a while. The aim is a short, focused exercise that leaves you ready for your next task, not a test you have to pass.