John Ridley Stroop


In 1935, John Ridley Stroop published an article entitled Studies of interference in serial verbal reactions that includes three different experiments. In his experiments, Stroop administered several variations of the same test for which three different kinds of stimuli were created. In the first one, names of colors appeared in black ink. In the second, names of colors appeared in a different ink than the color named. Finally in the third one, there were squares of a given color.  The task required the participants to read the written color names of the words independently of the color of the ink (for example, they would have to read “purple” no matter what the color of its ink was). In the 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 “purple” was written in red, they would have to say “red”, but not “purple”; when the squares were shown, the participant would have to say its color. Stroop, in the third experiment, tested his participants at different stages of practice at the tasks and stimulus used in the first and second experiments, to account for the effects of association.

Stroop first reported this effect in his Ph.D. dissertation. Current research emphasizes the interference that automatic processing of words has on the more mentally effortful task of just naming the ink color. The task of making an appropriate response – when given two conflicting signals – has tentatively been located in a part of the brain called the anterior cingulate. Although the functions of the anterior cingulate are very complex, broadly speaking it acts as a conduit between lower, somewhat more impulse-driven brain regions and higher, somewhat more thought-driven behaviors. The Stroop effect’s sensitivity to changes in brain function may be related to its association with the anterior cingulate.

As it is called today, the “Stroop Effect” refers to most humans being so proficient at reading, at perceiving whole words, that they do not easily notice the individual letters. The Stroop effect (sometimes called the Stroop test) is an outcome of our mental (attentional) vitality and flexibility. The effect is related to the ability of most people to read words more quickly and automatically than they can name colors. If a word is displayed in a color different from the color it actually names, then we have a hard time noticing the color of the ink. Testing in this area is performed in Psychology, Psychiatry, and in Vision Information Processing.

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Posted on August 15, 2012, in Uncategorized and tagged . Bookmark the permalink. 1 Comment.

  1. Thanks Robert! We use the Stroop concept as put forth by Dr. Ken Gibson. We put it in a group of activities called Verbal Eye Movements by Dr. Dave Cook. These activities definitely improve cognitive flexibility and tracking skills.


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