Try to identify the color of the word... Do you think it's easy? If it does not match the spelling? For example, the word "red" written in blue, and the word "green" - yellow. Not everyone will cope with such a test without a short delay. This delay is called the Stroop effect in honor of the John Ridley Stroop who first described a similar test in 1935.
For a certain period of time (30, 45 or 60 seconds; time can be selected in the settings), you need as much time to correctly determine whether the color name on the card on the left side of the game field corresponds to caption color on the card on the right. The caption on the card to the right is also a color name is usually different from the color of this caption.
The game has several levels of difficulty. As you progress through the game the levels of difficulty are increasing. First (zero level) you simply need to determine whether the color name on the one card corresponds to caption color on the another card, ie, choose one of the options "yes" or "no". The zero level is based on the five colors: black, red, blue, green, yellow. Further the number of colors, the number of cards and answer options are increased, a logical negation appears.