What is Stroop Effect Experiment ?

Introduction Of Stroop Effect Experiment 

The ‘Stroop Effect’ was named after John Ridley Stroop who discovered this occurrence in the 1930s. 

Stroop created three classic experimental research theories, while conducting his experiments with a group of participants. His first theory compared reading a list of words in black ink with reading the same list of words printed in different colours. The results showed that there was little or no difference in the time it took to read from both lists. 

He then compared the naming of colours for a list of solid colour squares with the naming of colours for a list of words printed in different colours. His participants took longer to name ink colours of different words. 

His experiments showed that the action of reading was automatic for most people. He demonstrated that when the brain was instructed to do the opposite and pay more attention to the colour of a word it struggled. His participants had to intentionally adjust their responses to complete the new task, as it is not as familiar to us as reading is. This phenomenon is called “interference”. 

His experimental results showed that people are more practiced at word reading than naming colours of the ink the words are written in, there is less interference with the word reading than there is with naming colours. As learnt experiences become a part of our memory, it teaches us over time that the meaning of words hold greater significance than the colours they are written in. 

Hypothesis for Stroop Effect Experiment : 

  1. The time taken will be more for incongruent tasks than for the congruent tasks.
  2. The error committed will be more for incongruent tasks than for congruent tasks.

Variables Used in Stroop Effect Experiment :

Independent variable (IV) – Nature of stimuli, i.e.  coloured patches and names of colours in different ink. 

Dependent variable (DV) – time taken and errors committed.

Relevant variables (RV) – extraneous sounds, illumination, concentration, mental set, etc. 

Material Used in Stroop Effect Experiment :

  1. List 1 consisted of 20 coloured patches printed in a random order.
  2. List 2 consisted of 20 names of the colours in different ink printed in random order. 
  3. Result sheet
  4. Wooden screen 
  5. Pencil.

Procedure to conduct Stroop Effect Experiment

The experimenter called the subject and rapport was established. Subject was told that there are going to be 2 lists. First the congruent list will be presented, the task for the subject is to name the colors as soon as possible. Then, the second incongruent list is presented here the subject has to read out the ink color of the words.

Instructions of Stroop Effect Experiments:

“This is a simple and interesting experiment. I will show you two lists, in the first your task is to tell the colour of the patches on the sheet, that is simply read out the words itself as quickly as you can. You will have to repeat this process 5 times continuously. In the second session, your task is to name the ink colours of the words instead of reading the word itself. This also you will have to repeat for 5 times continuously.”

Precautions to be taken while conducting Stroop Effect Experiments :

The patches of the colours should not be shown to the subject before the experiment. The time taken and errors committed should be noted down carefully. Subject should have normal vision. 

Plan of the Stroop Effect Experiment:

SessionMaterial No. of repetitions
1Coloured patches 5
2Names of the coloured ink5

Result Table (Sample) for Stroop Effect Experiment :


         Congruent list

Time Errors
42 secs 2
40 secs 0
38 secs 0
41 secs0
40 secs0


Incongruent List

48 secs2
38 secs3
33 secs0
1 min, 5 secs4
50 secs3

Congruent Total


 Congruent Average

Time Errors

 Incongruent Total


 Incongruent Average

Time Errors

Introspective Report (Sample) for Stroop Effect Experiment :

Q. How was the experiment?

  • “Interesting and surprisingly difficult. The first part was easy,but the second part was difficult and so i found this experiment interesting.”
  1. Q. Which session was difficult? And why?
  • “The second session was difficult for me, because I had to pay more attention to the colour of the ink.
  1. Q. What other difficulties did you face while performing the task?
  • “The difficulty was that I had to repeat the same thing again and again and I think I took more time for the second list. And when I had to repeat it I had to be more careful of what I say.”

Discussion (Sample) For Stroop Effect Experiment:

The purpose of this experiment was to observe that the incongruent task will require more time and errors committed were also more as compared to the congruent task.

The subject was called inside the cubicle and was seated comfortably. The rapport was established and instructions were given. 

In the congruent list for the first trial the time taken was 42 secs and errors committed were 2. As we proceed with the congruent list the time taken consistently dropped and the errors committed from the second trial to the fifth trial were none. A total of 201 secs was the time taken for the congruent list with a total of just 2 errors. The subject was seen to complete this task with no difficulty at all.

In the incongruent list, we could see the opposite of congruent list task, where the time consistently increased for 5 consecutive trials, but the errors committed were maintained except for the third trial where the time taken was the lowest and there were no errors committed. A total of 234 secs of time taken and total errors made in the incongruent list was 12.

It was observed that the subject was frustrated on not answering correctly. For every mistake made in the incongruent list, she was disappointed and was competitive in her previous trial. She also kept saying,” Why is this taking so long to answer?”, “It shouldn’t be this hard.” The more she tried to focus and more time she required to answer and errors made were more. 

Conclusion (Sample) of Stroop Effect Experiment :

The time taken will be more for incongruent task than for the congruent task. Or 

The error committed will be more for incongruent task than for congruent task is fully supported. 

Application of Stroop Effect Experiment:

  1. The stroop effect can be used as a part of cognitive tests in various clinical settings-increased errors could be attributed to problems in Attention or in ability to ignore/filter interfering factors.
  2. The stroop effect is also useful in marketing and advertisements. For example, billboards or magazine ads have to be designed carefully using the right font size and colour as it influences emotions and perceptions.
  3. It is also useful in conjunction with various neuropsychological assessments to examine a person’s executive processing ability which can further help In the diagnosis and characterisation of different psychiatric and neurological disorders.
  4. Researchers also use the stupid fact during Brain imaging studies to investigate regions of the brain that are involved in planning, decision making and managing real life interference ( eg, texting and driving)

Graphs for Stroop Effect Experiment  

  1. Error Made in both the lists – Congruent & Incongruent
  2. Time Taken In both the lists-  Congruent & Incongruent
  • References:

            Circcarelli, S. (2016) Psychology South Asian Edition, U.P: Pearson

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