Stroop effect: what it is and how it is used for diagnosis

The Stroop effect is a phenomenon related to focused attention and interference.

Many people, in their visit to the virtual world, come across a widely shared post, in which they can read names of colors but which are written in different colors.

Below the image appears the typical question: are you able to say the color without reading the word? This may seem like just another Internet challenge, but it is actually a cognitive test, with its own associated effect.

The Stroop effect is what is tested in this type of post, and it has been addressed experimentally. We'll take a closer look at what it is below.

What is the Stroop effect?

The Stroop effect, also called Jaensch's effect, is a semantic interference that occurs because of automated reading, causing us to give priority, unconsciously, to those stimuli that come in the form of written words rather than in other modalities such as shape or color.This phenomenon is named after the person who first described it, John Ridley Stroop, who described it for the first time, John Ridley Stroop. This phenomenon is named after the person who first described it, John Ridley Stroop.

While we will go into more detail in the next section, we will try to explain very quickly how the effect happens. Let's imagine that we have a list of words, each of them painted in a different color and that, coincidentally, each word refers to the color in which they are written. For example, the word 'BLUE' is painted blue, the word 'RED' is painted red, and so on.

If we were asked to tell the color of the ink in each word, it would be a very simple thing to do. We may just read the words, knowing that each one of them does not 'lie' or 'cheat', since it refers to the color in which it is written. The problem comes when the written color and its ink do not match, e.g., 'GREEN', 'GREEN', 'GREEN' and 'GREEN'.for example, 'GREEN' written in yellow. We can no longer read, we have to look carefully at the color of each word, plus we will go slower and possibly make a mistake or two.

Reading is something we have very automated. This is something that the vast majority of people who have the great gift of being alphabetic do not pay attention to. Reading each word, for anyone without problems such as dyslexia or very late literacy, is a very fast process. We just see the word and 'click', we have already read it and, depending on how abstract or concrete the concept it refers to is, we have made a mental image of its meaning.

That is why, while it is very easy for us to read, it is very difficult for us to try to put aside this automatic process .. We cannot simply turn off reading. The Stroop effect is very difficult to avoid, since we have to make a great effort not to read aloud what is in front of us during the test.

How was it discovered?

This phenomenon is named after the person who described it for the first time, John Ridley Stroopwho published his research in 1935 in his article Studies of Interference in Serial Verbal Reaction.

In this article, published in the Journal of Experimental Psychology, Stroop applied two tests. One, called Reading Color Names or RCN, in which the subject had to read the written meaning of the words, which were written in different colors, while the other one, called Naming Colored Words or NCW, the reader had to tell the color of the ink in which the words were written.

Specifically in the NCW tests, the subject, who had to tell the color of the ink of each of the words on the sheet, Stroop obtained very interesting results. Initially, the words shown to the participants were the same color as the ink in which they were written, i.e., the word "BLUE" was blue, the word "RED" was red, "GREEN" was green .....

When the subject was in this condition, they did not have much difficulty in saying the color of the ink, since it corresponded to what was written. The problem came when they had to say the color of the ink in the word but the name of the color the word referred to did not match. I.e., the word "RED" but written in blue ink, "BLUE" in yellow, etc.

He saw that, in addition to more errors in the second condition, the participants took longer to answer, participants took longer to answer, since they had to "neutralize" their reading process, which is automated, and try to say only the color of the word they were seeing.The participants had to "neutralize" their reading process, which is automated, and try to say only the color of the word they were seeing. It is this interference that is known as the Stroop effect in experimental psychology.

Attention is selective, that is, we focus it according to what interests us. However, if we try to focus on something by trying to inhibit such an automated response as reading words, this becomes especially complicated. The Stroop effect results from an interference between what we want to focus on and the reading that we can hardly ignore..

Are colors always used?

This same test has been replicated in other ways, without resorting to colors alone.

An alternative way is present names of animals inside animal silhouettes as well.The names may or may not correspond to the animal written inside them. For example, present the word "PIG" inside the figure of an elephant, or the word "DOG" inside that of a fish. Other versions include geometric figures (e.g., "TRIANGLE" inside a circle), names of countries, flags, fruits and an endless number of alternatives.

One of the reasons for the existence of these Stroop tests is, above all, the existence of people who have some kind of color blindness, either color blind for one of themeither color blind for one or two colors or blind for any color. In the latter case, people see the world in white and gray, which makes it impossible to test their ability to see the color of the ink in words since, basically, color does not exist for them.

Importance of the Stroop effect in the diagnosis of ADHD

The Stroop effect occurs as a consequence of having automated reading, and is a phenomenon that tests the person's selective attention. tests the person's selective attention, by trying to avoid reading the wordIt is a phenomenon that tests the person's selective attention, trying to avoid reading the word and saying some characteristic of that word, whether it is the color, the way it is presented or any other aspect.

Given this, the Stroop effect and, in particular, the tests based on it have been very useful to study the cases of people who have been diagnosed with attention deficit hyperactivity disorder (ADHD), as well as to clarify their diagnosis.

ADHD, according to the DSM, is characterized by a sustained pattern of inattentionwith or without the presence of hyperactivity and impulsivity behaviors. This pattern is more frequent and becomes more severe when compared with people who lack any disorder and are in the same developmental stage. These behaviors must manifest themselves in more than two different environments.

ADHD, although its diagnosis is criticized, is, according to health authorities, one of the most important clinical problems in terms of dysfunctionality, from childhood to adulthood, causing problems in multiple spheres of the person's life.

According to Barkley (2006), the central problem of this disorder is the difficulty in inhibitory control, shown in the form of impulsivity and difficult control of cognitive interference.. This has repercussions on executive functions such as working memory, both verbal and non-verbal, self-regulation, and synthesis and analysis capacity.

The Stroop effect serves as a measure of people's executive functioning, especially their ability to pay attention and concentrate. It allows to measure selective attention and to see how cognitively flexible or rigid the person is. It allows us to see if he/she is able to inhibit and control his/her dominant responses, in this case, reading words.

Cognitive flexibility refers to the ability to change, quickly and appropriately, one thought or behavior for another, according to what is being asked of the person in the task being performed.

On the other hand, cognitive rigidity is understood as the degree of difficulty that a person may have to ignore distractions, or the inability to control their incorrect answers, in this case, saying the name of the written word instead of the color of the ink in which they are written.

The Stroop effect is considered to be a reflection of problems in the prefrontal areawhich is in charge of executive functions. This test is of great importance in the field of neuropsychological evaluation thanks to its rapid application and easy interpretation.

People with adhd present a rather rigid cognitive style, with difficulty in inhibiting their behaviors when compared to people without any developmental pathology. They show greater interference in saying the color of words in the Stroop test without saying what is written.

Bibliographical references:

• Barkley, R. A. (2006). Attention deficit hyperactivity disorder. A handbook
• for diagnosis and treatment. New York: Guilford Press.
• Lopez-Villalobos, J. A., Serrano, I., Llano, J. & Delgado Sánchez-Mateos, J. López, S. & Sanchez Azon, M.. (2010). Utility of the Stroop test in attention-deficit/hyperactivity disorder. Journal of Neurology. 50. 333. 10.33588/rn.5006.2009418.
• Stroop, J. R. (1992). Studies of interference in serial verbal reactions. Journal of Experimental Psychology: General, 121(1), 15-23. https://doi.org/10.1037/0096-3445.121.1.15. https://doi.org/10.1037/0096-3445.121.1.15