Research Report On The Stroop Test

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The Stroop interference is postulated to be a processing mishap that occurs when the brain tries to process two parallel procedures simultaneously and cannot decide which one is more important (Hintzman et al., 1972). When reading through the congruent list of color-word pairings, the brain interprets the color and the word as the same and does not falter allowing the brain to vocalize the agreed response. Inversely, when the participant reads from the incongruent list, the brain comes into a problem because it tries to process the word name and the different color name at the same time, but the phenomenon we experience is that we cannot initiate a desired response until a decision has been made, resulting in a stutter. (Add transition) The hypothesis is that possibly with practice a person can train the brain to respond faster in determining which name is most important, reducing the completion time of the Stroop test.

In the field of Psychology, there are many variations of tests administered over hundreds of studies over the years, none more revisited than the Stroop Test. This test is one of the most popular because of its simplistic design and quick administration but it was the phenomenon that is associated with the test that really builds interest. J. Ridley Stoop devised the test in 1935 to test the interference in verbal readings of a list of congruent and incongruent word and color pairs. A congruent color pair would be the word red paired with the color red, and an incongruent pair would be the color red paired with the color blue. The interference Stroop was looking for was that when a participant tried reading the incongruent list of words (incongruent meaning a color name written in a different color in then the name) they would slow down significantly and more errors in color naming would arise. He used a group of 70 undergraduate students (14 males and 56 females) for his first experiment. In the experiment, the participants read from two pages of words, a RCNb (reading color name printed in black) and RCNd (reading color name printed in different color). The idea for this experiment was to have the students read each color word while ignoring the color of the print in the word. Despite instructions to read quickly and correct all errors, 14 of the 70 students left errors uncorrected, but the total number of errors was negligible. The averaged numbers showed only a slight increase going from RCNb to RCNd, showing an average of 41 seconds for the RCNb test and 43.3 seconds for the RCNd test. When sorting the students into their individual grades, the first and second years showed the most slowing in time while the third and fourth years showed very little change, showing that the later the year of the student the less time it to them to read the list.

Stroop's second experiment was very similar to his first, but in this instance, the participants read the color of the words printed instead of the word itself. The setup of the test did not change from the previous experiment other than the participants read the colors not the word. In this test the participants had two sheets, consisting of a NC (name of color) and NCWd (same as RCNd except name the color of the words print). Though the tests ran similarly, the results showed a drastic change in reaction time. The average reading time for the students to finish the NC task resulted in a time of 63.3 (CITE?) second, but the average for the NCWd test was 110.3 seconds. When these students separated into their perspective years, the time to complete the task decreased as the students year increased, which again showed a negative connection between task time and grade level.

Stroop's final experiment delved into the idea that practice in the tests over many days could possibly change the reaction time of the readings in all of his tests. The schedule for studying was as follows: two days of studying RCNd, then one NC, eight days of studying NCWd, one day of NC, and then two more days studying RCNd. Doing this task improved the speed of reaction for the NC and NCWd task but greatly reduced the speed for the RCNd task because the participants had mainly been training the ability to read the color and encode that task as the primary focus and putting word name reading as second.

(Hintzman et al., 1972) used the Stroop interference concept to examine whether the phenomenon that arose with the original test is an input or output confliction. The researchers separated the test into four parts that they labeled S (word named color of ink), D (word named color other then the printed name), N (matches non-color words with one of the colors from the experiment according to the first letter and length of word), and C (which jumbled the letters in the color names except for the first letter). The researchers recorded their times as such: S, 1.1; D, 13.2; N, 1.9; and C, 2.8 in seconds. What the researchers found in testing showed that there is a significant increase in reading time between the S and D, providing support for the theory that there is an interference problem when the brain tries to "output" the information processed when reading the incongruent D list and not the pre-encoded S list that encodes for the same response.

Gender differences have also been a constant topic in Stroop test interference research and appeared to also have inferences into the study performed in this paper given that roughly 86% of the participant's gender turned out female. (Baroun, Khader & Alansaari, Bader, 2006) examined a group of Kuwaiti males and females consisting of 504 university students: 122 men and 382 women. The tests setup imitated the setup of the original Stroop test with a congruent and incongruent list of words. The test showed a significant decrease in color reading for congruent and incongruent lists but no significant difference between the average times for the reading of the word names. This result support the idea that girls have a certain amount of "training" (Stroop, J.R. 1935) toward the identification of colors through associations with their everyday lifestyle in determining dress and social conversation.

(MacLeod, C. M. & Dunbar, K. 1988) took an approach that tested the idea of congruent and incongruent Stroop interference while eliminating any postulation that using colors for words may have caused the confliction. The researchers performed a classic Stroop test but instead of words, substituted colored shapes of various different shapes and colors while training the participants to reduce the reaction time as the other journals had done. After 20 days of practice, they found that the shape naming and color naming reaction times had decreased and the shape naming had become almost an automatic response.



In this experiment, participants consisted of five groups of undergraduate students with three students in each group. The age of participants averaged to be 24.53 years old and made up of two males and 13 females. Out of the 15 students, there were three Hispanic participants and the remaining 12 were Caucasian. Participation in the Stroop test was required as part of the curriculum for a Psychology course.


The materials included three test papers for each of the groups, a stopwatch provided by the group either through cell phone or by watch, paper for recording as provide by the groups, and pencils to record their data. The Stroop Test papers were typed in Microsoft Office Word and incorporated 36 words in two columns; one congruent and one incongruent. The colors used were blue, orange, red, black, green, and yellow. The congruent list used each of the words three times written in their own color, but the incongruent list consisted of each word written three times in a random color (one of the 6) different from the word.


Each of the participants was briefed about the experiment and told to read the list of words while being timed by one of the other participants in their group. The groups each set up a master sheet to record the race, sex, age, participant number, congruent reading time, incongruent reading time, and incongruent reading time with five minutes of practice. Participants were instructed to read the congruent list first while being timed, and then when finished, place the test face down so the participant could not see the words. Each of the members took a turn timing one of the others in their group while one of the group members recorded all of their times on a master sheet. The same was done for the first reading of the incongruent list. For the final reading of the incongruent list, the participants were given a five-minute period where they focused on practicing to read the incongruent list. Once the time period was up the participants put the paper down again and waited briefly before doing another timed reading of the incongruent list. Once the last reading time was recorded for all three participants of each group, the master sheets were collected and the times for each reading were averaged along with the participant's mean age. The recorded times were plugged into a program that determines whether the differences in times turned out to be significant.


The reaction times for congruent and incongruent tests were averaged as followed: Test 1-congruent reading- 8.63 s, Test 2-incongruent reading (no practice)- 15.06s, and Test 3- incongruent reading (5 min. practice)- 14.01s. The results were checked using an analysis of variance (ANOVA) test, which determines the significance of differences between the times. The three times showed a significant difference in times, F (2, 28)= 12.01, p < 0.05, which did not occur between the incongruent times which the hypothesis did not anticipate for. The participants completed the congruent list, on average, significantly faster than the readings of the incongruent lists.


The Stroop test has