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Effects of the Stoop Effect on Response Time

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In a research using the Stroop task to demonstrate Stroop interference, the present study analyzed the response time in different conditions and compared the incongruent condition to the facilitated condition. The purpose of the Stroop effect experiment is to ascertain our attentional capabilities in terms of variability and flexibility. Therefore, if various words were displayed in different color ink with the color on the words different, we definably will have difficult time telling the words apart from the color. There were 150 participants involved in this experiment. The participant was required to look at the colored words and the color on the ink while ignoring actual words. The results were that the reaction time was high and few errors were made in that congruent condition. At the end of the study, it is conclusive that when the process of reading is a simple automatic process, simple tasks like color identification becomes difficult for a person


Stroop effect is one of the phenomena in cognitive science and psychology. Introduced in 1935, Stroop effect originated from theory of the automatic process. We are used to some of the processing activities until we have gotten used to them and have become automatic. for instance, driving a car, typing. These processes have formed part of our automatic response unit, where they are unavoidable, fast and does not require ant attention. Stroop had a belief that identification may be part of automatic process. He argues his belief by conducting an experiment where participants had to read sequence of words printed rapidly. It was noted that naming slowed down when colors and names conflicted. The Stroop effect suggests that extraction of words meanings happened as participants were not attempting to process it.332hbs the prefinal scoop effect was found.

Effects of the Stoop Effect on Response Time

The Stroop effect has been and still is one important topic in experimental Psychology. The Stoop task is still used today to study several other topics and to investigate the effects of many different things on the human and animal mind. The Stroop Effect is a test used to demonstrate the reaction time of a task. Because of its versatile nature, it can be used to determine the effect of various variables on response time”and therefore the processing time”, illustrating differences between automatic processing versus conscious visual control.

In this paper, I aim to analyze the findings of our own Stroop task performed in our Research Methods in Psychology class at Florida Atlantic University, and tie that to previous experiments done in the past. I aim to explore similarities and differences between our experiment and theirs and to examine the variables involved in our experiment and what they mean to the overall results of the Stroop Effect.

The Stroop effect is tested using two or more groups of words that match the other groups in frequency (Thorndike and Lorge 1944), number of letters, and number of syllables. I can be presented in many different ways, which allows for experimenters to use it in various different scenarios and dealing with several different matters. The independent variables can be the sex of the participants, or whether they are smokers or not”as seen in the research articleNicotine abstinence produces content-specific Stroop interference by Todd M. Gross, Murray E. Jarvik, and Marvin R. Rosenblatt”, level of tiredness, age, and many others. For that reason, in order to avoid confounding variables, the experimenter must be very careful to keep all the other variables constant. The dependent variable is the response time”the time it takes the participants to finish the task.



One hundred and fifteen participants (98 female, 17 male) whose average age was 21.9 years (range = 16-53) completed the experimental task. The participants were recruited from an undergraduate level research methods course. The participants got course credit for their participation in the study. I was a participant in this study. Participants were treated in accordance with the Ethical Principles of Psychologists and Code of Conduct (American Psychological Association, 1992)


Reaction times were measured using a timer on the projector, and all participants participated at the same time. We used a printout to present stimuli consisting either of Arabic numerals (1,2,3) or crosses (+). Both sets of either numerals or crosses could be made to appear in groups of one, two, or three identical figures. The naming condition caused no interference, as the participants only had to read the number out loud (2 = saytwo out loud). The counting condition also produced no interference, as the participants only had to count the number of crosses out loud (+++ = saythree out loud). The incongruent counting condition, on the other hand, caused interference because the participant had to count how many numbers were shown, while reading a different number (2222 = sayfour out loud). And the congruent counting condition caused facilitation as the number of numbers counted was the same as the name of the number (4444 = sayfour out loud). Each list had 32 numbers presented in a column (one per page), printed on 4 different sheets of 8.5 x 11 paper (12 pt font, centered on each page). Numbers were randomized on each list and were the same across all participants.


The experiment was performed in an in-class setting. The instructions were given by the professor. All participants were supposed to count out loud the number of symbols (Arabic numbers or crosses) as fast as possible and record the time taken to finish each task (each list of numbers). Participants were paired in groups of two, and while one person read the numbers, the other recorded the time. There were 4 different conditions: a naming condition (no interference), a counting condition (no interference), an incongruent counting condition (interference), and a congruent counting condition (facilitation). All the participants participated in all four conditions, and in the same order. The task was to r ead the number, count the quantity, ignore the number identity for counting conditions, and count the number of digits. The independent variable was the level of congruence in number/symbol lists (IV had 4 levels (incongruent, congruent, reading, counting) and the dependent variable was the reaction time (in seconds) for each list. all participants were also experimenters and are authors.


The incongruent counting list took participants the longest to complete. The reading list took the shortest time. The neutral counting list and the congruent list had similar results, as seen in Table 1. We had 115 participants, of which 17 were male and 98 were female. The age range was 16-53, and the mean 21.9. We ran a one-way analysis of variance (ANOVA) to determine if the means were significantly different in each condition and found that F (3,456) = 172.9, p < 0.0001, as seen in Figure 1. We conducted a Tukey's HSD post-hoc test to find out which means were significantly different (seen in Table 1). The Tukey's HSD post-hoc test was conducted to determine if the incongruent counting list would cause Stroop interference, and thus a longer response time. We found that there was a significant difference between the reading list (M=11.6, SD=1.7) and the neutral counting list (M=13.8, SD=2.3), between the reading list (M=11.6, SD=1.7) and the incongruent counting list (M=18.9, SD=3.6), between the reading list (M=11.6, SD=1.7) and the congruent counting list (M=13.2, SD=2.4), between the neutral counting list (M=13.8, SD=2.3) and the incongruent counting list (M=18.9, SD=3.6), and between the incongruent counting list (M=18.9, SD=3.6) and the congruent counting list (M=13.2, SD=2.4). The difference was NOT significant between the neutral counting list (M=13.8, SD=2.3) and the congruent counting list (M=13.2, SD=2.4).


In this study, our goal was to determine rather or not the Stroop task would cause Stroop interference or not, and from that, to be able to measure how much interference was caused and possible reasons why. The main finding of this study was that the incongruence in what the participants read and what they are required to say out loud caused Stroop interference. We determined that the participants had the least problem to read the numbers being presented to them (reading list) and had the most problem (had a longer response time) to count the number of numerals being presented when the name of the numerals were not the same as the number of numerals (incongruent counting list).

The findings were in accordance with the findings presented in Windes'study of Reaction Time for Numerical Coding and Naming of Numerals. Although in the Windes'research, he states that the results offer no clear answer he also states that there are possible sources of delay in naming stimuli and those are identification-task conflict and response conflict.

The limitations of the study were that we were not able to separate age groups and analyze the different data separately, and instead, our age group was very broad, with a few outliers. We also we not able to conduct the experiment more than once and compare the results. Another limitation of this study could be that we did not control all other possible variables such as smoking, level of tiredness, and if participants had caffeine prior to the experiment or not.

From this study, it is possible to conclude that the incongruent condition was the slowest, and this supports our hypothesis that an incongruence in the list would cause a Stroop interference. There was no significant difference between the neutral counting and congruent counting conditions because they do not provide any sort of facilitation or interference.


This experiment, the problem and question are to carry out a word influence of what we sew and how our brains have handled mixed messages. The main reason behind our hypotheses is that we did a research on this topic and came up with our hypothesis. our hypothesis is that if reaction of the people against time doesn't change in the same range, then words are great influencer in what we are able to see and that the brain does not handle mixed signals as well.


Perret, P. & Ducrot, S. Psychonomic Bulletin & Review (2010) 17: 550. https://doi.org/10.3758/PBR.17.4.550

Windes, J.D. (1968). Reaction Time for Numerical Coding and Naming of Numerals. Journal of Experimental Psychology, 78(2), 318-322.

MacLeod, C. M. (1991). Half a century of research on the Stroop effect: an integrative review.? Psychological bulletin,? 109(2), 163.

Liotti, M., Woldorff, M. G., Perez, R., & Mayberg, H. S. (2000). An ERP study of the temporal course of the Stroop color-word interference effect.? Neuropsychologia,? 38(5), 701-711.

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