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 on average longer than participants who did test #1.
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” 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 was used succeeding each other but the words were printed in an 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” were 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 a sample of opportunities because of the limited time given. These participants will be randomly assigned to 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). StopWatch. Pencil. Paper. Consent form (attached to the Appendix). Debriefing Note (attached to the Appendix).
Participants will do one of the two tests and will be informed about the instructions involving task
The participant will be asked to sign the consent form of whether or not they would want to participate in the experiment
The instructor will present the participants with the list of 20 words (participants need to correct themselves when a mistake is made)
Participants will start reciting the words when they are instructed to or when the instructor has started timing
The time will stop when the last word is recited
After the experiment, participants will be debriefed about the Stroop Effect and the other theories being investigated
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 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 the 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 fluent. The outcome of this experiment can be explained through Schneider and Shriffin’s theory of automatic processing were the participants in test #2 took a long 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 that 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.
Stroop, J. R. (1935). Journal of experimental psychology. Studies of Interference in Serial Verbal Reactions, XVIII(6), (p647-649). Hill, G. (1998,2001).