An experiment investigating the effects of interference on speed estimates during the Stroop task Nicharee Thamsirisup (Nid) IB Psychology Standard Level Abstract: This experiment is to investigate the effect of color interference in speed estimates of the Stroop task which was first researched by John Ridley Stroop in 1935. This can be investigated by seeing the time difference between the task of identifying colors when color words are printed in the same color as their semantic meaning (test #1) and when they are printed in different colors as their semantic meaning (test #2).
The research hypothesis is that the average time will be higher in test #2 because of the interference in the color detection task. The experiment uses independent measures and opportunity sampling of bilingual students aged from 16 to 18 years old. The results supported the hypothesis since the participants who did test #2 took 8. 8 seconds in average longer than participants who did test #1. Introduction The aim of this study is to investigate the effect of interference on speed estimates during the Stroop task.
The Stroop task was first experimented by John Ridley Stroop in 1935. The Stroop Effect involving the Stroop task refers to a phenomenon in which it is easier to say the color of a word if it matches the semantic meaning of the word. Stroop (1935) began investigating the phenomenon of interference by using a color-naming task. The experiment was called ““The Effect of Interfering Color Stimuli Upon Reading Names of Colors Serially” in which he conducted on seventy college undergraduates (14 males and 56 females).
In the experiment, the participants were to do two tests, one test is with a list of words printed in black and another test is with a list of words printed in colors (red, blue, green, brown and purple) different from its name (e. g. blue printed in red). The colored words were arranged so that each color would appear twice in each column and row and no color were used succeeding each other but the words were printed in equal number of times in each of the other four colors (e. g. the word ‘red’ printed in blue, green, brown and purple inks or the word ‘blue’ was printed in red, green, brown and purple inks).
Participants were asked to read the words as fast as possible and correct any possible mistakes. Results show that it took the participants an average of 2. 3 seconds longer to read 100 color names printed in different colors than to read the same words printed in blank1. Schneider and Shiffrin (1977)2 explained this phenomenon in terms of “automatic processing” where in the experiment of Stroop, reading skills are automatically triggered and intrude upon the intentional process of color detection task. Automatic processing occurs with very few to none conscious resources.
Logan (1990)2 also stated that automatic processing can develop through practice as it will require less effort or thoughts and becomes more rapid to retrieve the appropriate responses to the stimulus. These automatic thoughts can be retrieved by accessing the ‘past solutions,’ for example, children will first use their fingers to do simple addition (e. g. 1+1=2), however, as more practice occurs, they will be immediately able to answer it just by seeing it within a second with no attention required. Design:
The experiment used independent measures (participants only take part in one of the two tests) which reduced the practice and made it more difficult to speculate the aim of the study. In test 1, the incongruent condition, participants were asked to read a list of different words of the colors printed in different colors to their semantic meanings (e. g. the word BLUE printed in green ink). In test 2, the congruent condition, participants were asked to read a list f different words of the colors printed in the same color as their semantic meanings (e. . the word BLUE printed in blue ink. ) Also when they made a mistake, they had to correct it. The dependent variable is the time taken for the participants to read the list. The controlled variables include the font of the words, the number of words per test and the size of the paper used to present the list of words to the participants. The participants were given the consent form and were told about the procedures in the experiment before starting. Participants were allowed to withdraw at any point during the experiment and after completion f the experiment, they were given a debriefing note and the ability to choose whether they want their results to be used or not. The debriefing note and consent form will be attached in the appendix section. Participants: The participants in my experiment include 30 international students (15 males and 15 females) and they will be grouped into two conditional groups: incongruent condition and congruent condition where they will be presented with a list of 20 words specific for that condition. The target population is bilingual adolescents with the age range of between 16 to 18 years old.
The method of selection of participants was by using sample of opportunity because of the limited time given. These participants will be randomly assigned into the two groups or meaning that one person will do only do one test. Materials: * Test #1: List of 20 Congruent words (on one paper) * Test #2: List of 20 Incongruent words (on one paper) * Stop Watch * Pencil * Paper * Consent form (attached to the Appendix) * Debriefing Note (attached to the Appendix) Procedure: 1. Participants will do one of the two tests and will be informed about the instructions involving the task 2.
The participant will be asked to sign the consent form of whether or not they would want to participate in the experiment 3. Instructor will present the participants with the list of 20 words (participants need to correct themselves when a mistake is made) 4. Participants will start reciting the words when they are instructed to or when the instructor has started timing 5. The time will stop when the last word is recited 6. After the experiment, participants will be debriefed about the Stroop Effect and the other theories being investigated 7. Participants have the right to allow or withdraw their results from the experiment
Results: In Test #1, the mean for the participants to complete the stroop task where the color of the ink is the same as its semantic meaning is 13. 6 with a standard deviation of 2. 2. The time ranges from the fastest time which is 10. 6 seconds to the slowest time which is 18. 2 seconds. In Test #2, the mean for the participants to complete the stroop task where the color of the ink is different from its semantic meaning is 22. 4 with a standard deviation of 4. 1. The time ranges from 16. 1 to 31. 3 seconds. The mean and the standard deviation are taken into account because it is assumed that the results will form a normal distribution.
The mean is the average time of all the time of the participants and the standard deviation is the measure of how spread out the numbers is from the mean. The median and the range are not taken into account. ?? Test Number| Mean| Standard Deviation| 1| 13. 6| 2. 2| 2| 22. 4| 4. 1| *The procedures for finding the mean and standard deviation are in the appendix Discussions Discussion of Results: Even though there were variations from the original Stroop experiment, it is able to investigate, with high reliability, the effect of interference in speed estimates during the Stroop task.
The results show accuracy with the Stroop task done in 1935 by John Ridley Stroop since there is a significant difference between the amount of time a person took to complete the task where the colors were congruent with their semantic meaning (Test #1) and where the colors were incongruent with their semantic meaning (Test #2). The participants took a longer amount of time to complete test #2 compared to test #1. The difference between the averages of these two tests is 8. 8 seconds. Most of them participants in Test #1 took around the same amount of time to complete the task as can be seen by the low standard deviation of . 2, but in test #2, the amount of time among the participants was more spread out (S. D=4. 1). One possible explanation for this is the participant’s level of English proficiency, since if a person is more fluent in English, he or she may be able to identify the colors more quickly as compared to a person who is not as fluent. The outcome of this experiment can be explained through Schneider and Shriffin’s theory of automatic processing where the participants in test #2 took longer time because the process of reading interfered with the color detection task.
Since reading has become practiced very often, it is automatically activated without the person’s consciousness, therefore, it requires more attention for the participants in this group to correctly identify the colors without just reading the word. The participants in test #1 were able to identify the colors faster since after reading several words, the participants will read the words without any interference from the difference in the word’s semantic meaning. Limitations and Improvements: The results from the experiment have low generalizability since this experiment was conducted on bilingual students aging from 16 to 18 years old.
There may be other factors which may cause the participants to identify the colors faster e. g. being an English native speaker. Some of the participants also didn’t correct themselves when they have misread the color so two seconds were added into some of the results (interrupting the participants and make them correct their mistake was avoided since this would impact the results even more). Some of the participants who did test #1 also started reading the word itself after seeing recognizing the pattern and ignoring the real task which is to identify the color. This can be improved by adding an incongruent word (e. g. he word BLUE printed in RED) into the word list of test #1 and informing the participants in the instructions so that the participants will concentrate on identifying the colors. To improve the sampling group, we can change the sample group to a wider range of age for example from 10-30 years old instead. Despite the limitations, the result is still accurate since there is a supporting theory and it agrees with the result of the Stroop task in the original experiment. APA List of References: 1. Stroop, J. R. (1935). Journal of experimental psychology. Studies of Interference in Serial Verbal Reactions,XVIII(6), (p647-649). . Hill, G. (1998,2001). Oxford revision guides a level of psychology. (p. 118) Oxford University Press. Appendix: Consent Form * I have been informed of the nature and procedures involved in the experiment * I understand that I have the right to withdraw at any point after the experiment has begun * I will not be harmed in any way upon participating in the experiment * I understand that my identity will not be connected to my data and that all information I provide will remain confidential * I will be debriefed at the end and be able to know my results
By signing this form, I have read the above information and agreed to give my consent to participate in this experiment: Printed Name:____________________________ Signature: _______________________________ Debriefing Note You have just been tested on the Stroop task, producing the Stroop Effect whereby you read the word itself faster than you could identify the color you see. This can be explained through the theory of “Automatic Processing” in which the process of reading becomes practiced so often that it is automatically activated without you being conscious.
The process of reading is automatically triggered because you are conditioned to reading and this interferes with the task of color detection. Thank you for your participation in the experiment. Instructions: After you have signed the consent form, in the following minutes, you will be presented with a list of 20 words. You have to read out loud the color that the words are printed (not the word itself) in order that they are presented. You will be timed while reading these words out loud. If you have made a mistake, please correct yourself before continuing the next word.
You may start when you are ready. Materials: 1. 1. RED 2. GREEN 3. PURPLE 4. RED 5. BLUE 6. BROWN 7. BLUE 8. GREEN 9. BROWN 10. PURPLE 11. RED 12. BLUE 13. BROWN 14. PURPLE 15. GREEN 16. BLUE 17. RED 18. GREEN 19. BROWN 20. PURPLE List of 20 Congruent Words (TEST #1) 3. List of 20 Incongruent words (TEST #2) 21. RED 22. BLUE 23. PURPLE 24. BROWN 25. PURPLE 26. BLUE 27. GREEN 28. RED 29. BROWN 30. PURPLE 1. RED 2. BLUE 3. GREEN 4. PURPLE 5. BLUE 6. GREEN 7. BROWN 8. RED 9. GREEN 10. BROWN *The words were actually printed out in Times New Roman size 24 Raw data:
Time for the Stroop task (sec)| Test #1| Test #2| 10. 6| 16. 1| 10. 7| 17. 1| 11. 2| 17. 5| 11. 7| 18. 4| 12. 2| 19. 9| 12. 2| 20. 5| 13. 3| 21. 1| 13. 4| 22. 5| 13. 8| 22. 8| 14. 5| 23. 8| 15. 1| 24. 1| 15. 2| 24. 4| 15. 9| 25. 5| 16. 4| 31. 3| 18. 2| 31. 3| Finding the Mean: Test #1 Using the formula x-=? xn where x– is the mean, ? x is the sum of all the terms and n is the number of terms x-=204. 415 x-? 13. 6 seconds Test #2 x-=336. 115 x-? 22. 4 seconds The mean was used since it is assumed that the population is a normal distribution Finding the Standard Deviation:
For Test #1: Time (seconds) (x)| Mean (x-)| Deviation (d)(x-x-)| Squared Deviation (d2) (x-x-)2| 10. 6| 13. 6| (10. 6-13. 6)= -3| (-3)2= 9| 10. 7| 13. 6| (10. 7-13. 6)= -2. 9| 8. 41| 11. 2| 13. 6| (11. 2-13. 6)= -2. 4| 5. 76| 11. 7| 13. 6| (11. 7-13. 6)= -1. 9| 3. 61| 12. 2| 13. 6| (12. 2-13. 6)= -1. 4| 1. 96| 12. 2| 13. 6| (12. 2-13. 6)= -1. 4| 1. 96| 13. 3| 13. 6| (13. 3-13. 6)= -0. 3| 0. 09| 13. 4| 13. 6| (13. 4-13. 6)= -0. 2| 0. 04| 13. 8| 13. 6| (13. 8-13. 6)= 0. 2| 0. 04| 14. 5| 13. 6| (14. 5-13. 6)= 0. 9| 0. 81| 15. 1| 13. 6| (15. 1-13. 6)= 1. 5| 2. 25| 15. | 13. 6| (15. 2-13. 6)= 1. 6| 2. 56| 15. 9| 13. 6| (15. 9-13. 6)= 2. 3| 5. 29| 16. 4| 13. 6| (16. 4-13. 6)= 2. 8| 7. 84| 18. 2| 13. 6| (18. 2-13. 6)= 4. 6| 21. 16| n=15| | | ? (x-x-)2=70. 78| *The deviation can be found by subtracting the time by the mean of all the numbers (found earlier). The square deviation can be found by squaring the deviation and ? (x-x-)2 can be found by adding up all the squared deviation for different times. Using the formula for standard deviation: Where: = standard deviation ?= sum of x= each value in the set x-= mean of all values in the data set = number of value in the data set Standard Deviation= 70. 7815 ? 2. 2 For Test #2: Time Seconds (x)| Mean (x-)| Deviation (d) (x-x-)| Squared Deviation (d2) (x-x-)2| 17. 1| 22. 4| -5. 3| 28. 09| 17. 5| 22. 4| -4. 9| 24. 01| 18. 4| 22. 4| -4| 16| 19. 9| 22. 4| -2. 5| 6. 25| 20. 5| 22. 4| -1. 9| 3. 61| 21. 1| 22. 4| -1. 3| 1. 69| 22. 5| 22. 4| 0. 1| 0. 01| 22. 8| 22. 4| 0. 4| 0. 16| 23. 8| 22. 4| 1. 4| 1. 96| 24. 1| 22. 4| 1. 7| 2. 89| 24. 4| 22. 4| 2| 4| 25. 5| 22. 4| 3. 1| 9. 61| 31. 3| 22. 4| 8. 9| 79. 21| 31. 3| 22. 4| 8. 9| 79. 21| n=15| | | ? (x-x-)2=256. 7| Standard Deviation= 256. 15 ? 4. 1 Finding the Median: Since there is odd number of terms (15 terms), the median is the middle number which is number 8 when you organize the number in increasing order from smallest to largest: Test #1: 13. 4 Test #2: 22. 5 Finding the Range: The range is the difference between the largest and the smallest value of the data. Therefore, take the largest value and subtract with the smallest value. Test #1: 18. 2-10. 6 = 7. 6 seconds Test#2: 31. 3-16. 1= 15. 2 seconds Table: Median and Range of the two Tests | Median (sec)| Range (sec)| Test #1| 13. 4| 7. 6| Test #2| 22. 5| 15. 2|
In Test #1, the speed or the time for the participants to completely read the words ranges from 10. 6 seconds up to 18. 2 seconds. The difference between the slowest and the fastest speeds (range) is 7. 6. The median for Test #1 is 13. 4 seconds. In Test #2, the speed ranges from 16. 1 seconds to 31. 3 seconds and the difference between the slowest and fastest speeds (range) is 15. 2. The median for Test #2 is 22. 5. * In test #1, most of the participants took around 13 to 14 and 15 to 16 seconds to complete the task . * In test #2, the histogram is skewed to the left where most participants spent from 16 to 26 seconds to complete the task.