Say the ink, not the word
The word says BLUE and it is printed in red. The answer is red. Thirty seconds.
The word says BLUE and it is printed in red. The answer is red. Thirty seconds.
Word and ink disagreeFour times in five
Answer the inkFive colours, keys 1–5
Right minus wrongGuessing costs you
A colour word fills the screen, printed in one of five colours — red, blue, green, yellow, purple. Ignore what it says and answer the colour it is printed in, by tapping one of the five buttons or pressing 1 to 5. The next word appears at once.
You get thirty seconds. Your score is right answers minus wrong ones, so hammering the keys gets you nothing: at five colours, random guessing loses about as often as it wins. Roughly one word in five is printed in the colour it names, which is there to catch anyone who has started answering by rote.
Everyone gets the same sequence today. The server marks the answers against its own copy of it — your browser never says whether it got one right.
Answers closer together than 150ms are not counted — that is faster than the word can be read.
The effect is named after John Ridley Stroop, who published it in 1935: naming the ink a word is printed in takes measurably longer when the word names a different colour. Reading is so automatic in a literate adult that it happens whether or not you want it to, and the answer you need has to win a race against the answer you did not ask for.
The delay is around 100 to 200 milliseconds per item and it does not really go away with practice. What does improve is the strategy — people learn to defocus the word, or to look slightly away from its centre, which is a legitimate way to play.
With five buttons and no penalty, the best strategy would be to mash — one in five lands, and a fast masher beats a careful reader. Subtracting wrong answers makes guessing worth exactly nothing on average, which leaves reading the ink as the only way to score.