The Stroop effect is a demonstration of the reaction time of a task, when the name of a color ( "red," "pink,") is printed in a color not denoted by the name (the word "green" printed in blue ink instead of green ink), naming the color of the word takes longer and is more prone to erors than when the color of the ink matches the name of the color. The effect is named after John R. Stroop who first published the effect in English in 1935. The effect had previously been published in 1929, but only in Germany. The original paper has been one of the most cited papers in the history of experimental psychology, leading to more than 700 replications. The effect has been used to create a psychological test that is widely used in clinical practice and investigation.The experiment required the participants to read the written color names of the words independently of the color of the ink . Second experiment, stimulus 2 and 3 were used, and participants were required to say the color of the letters independently of the written word with the second kind of stimulus and also name the color of the dot squares. If the word "yellow" was written in red, they would have to say "red," but not "yellow"; when the squares were shown, the participant would have to say its color. In the third experiment, tested his participants at different stages of the tasks and stimulus used in the first and second experiments, to account for the effects of association.