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The Effects of Reading and Naming Colors on Reaction Time

Eliza Chulyakova

Queens College

Abstract
The purpose of this experiment was to examine and test the effect of varying levels of interference on one’s response time to name errors and font colors. This experiment is a modified version of an experiment conducted by Stroop in 1935 which tested the interference between incongruent word-color combinations. Seventeen Queens College students participated in this experiment. The independent variable of the experiment was interference, and it consisted of three levels; colored “XXX” symbols, congruent color-word combinations, and incongruent color-word combinations. The dependent variable within the experiment was the mean response time it took participants to accurately choose the color that represented the word set before them. Results have revealed that when different levels of interference were administered, a change in the overall mean response-time becomes evident; as the level of interference increases, so does the number of errors and the time it takes for participants to respond .

The Effect of Word and Color Interference on Response Time Interference is categorized as the presentation of two or more stimuli at a given time. Ever since the 1800’s, the effects of interference in several serial verbal reactions have been studied. These studied intended to reveal the various effects that are a result from interfering stimuli that which would not have been present if only one stimuli were present. The experiment that was conducted in class tested the effect of varying colors on the level of interference on response time to name font colors and naming errors. This experiment was a modified version of an experiment that was conducted by J. Ridely Stroop in 1935. In the Stroop experiment, the participants were directed to read the names of the colors, as well as, the name of the colors of the ink the words were written in. The purpose of the experiment was to test the effect of interference stimuli on reaction time. Within the experiment, 100 students, 88 college undergraduates, 29 males and 59 females, and 12 graduate students, all females served as subjects. The participants were placed in a room that which was seated next to a well-lit window. A within-subject design was used where all the participants within the study experienced both conditions. Every participant read two whole sheets of each test at one sitting. The participants were given two lists, one that contained colored squares and another containing colored words which spelled the name of a different color in which it was written. The participants were then told to call out the color of the ink for both lists as quickly as possible while being timed. The results of his experiments revealed that it took participants longer to say the color of the words rather than the color of the squares. He further concluded that the reason for an individual’s decline in speed was attributed to the interference between ones brain simultaneous attempt to read the name of the incongruent color and them saying the color of the word that they see. The purpose of this experiment, that which tested the effect of word and color interference on response time, was to demonstrate if the results of Stroop’s experiment were due to the presence of incongruent words or the presence of a word in general, or if both had somewhat attributed to the overall result. Within the experiment three interference conditions were measured. The first condition that the participants were presented with was a set of different colored “XXX” letters (yellow, orange, blue, purple, green and red), which were similar to that of Stroop’s colored squares, The second condition was a set of congruent, or matched colors, and word combinations. Lastly, the third condition the individuals were presented with was a combination of incongruent or mismatched colors and word combinations. The addition of the third condition was intended to distinguish which variable attributes to Stroop’s findings.

Method

Participants

A class total of 17 CUNY Queens college, 4 male and 13 female students, within an experimental psychology participated within this study to satisfy a course requirement.
Setting

The experiment took place in the experimental Psychology lab room A-135H in the Science building of Queens College.
Materials
Participants used a 24in screen Mac Desktop in which obtained the program developed by John Krantz necessary for this experiment. On this site, an option for three different sets of “cards” is available. The first deck of cards were Matched by color/word combinations, in which the words were blue, green, yellow, orange, red and purple written in the colors they each described. The second decks of cards were mismatched by color/word combinations, in which the words blue, green, orange, red, orange, and purple were written in four other colors that they don’t describe. The final deck of cards was a deck of 100 “cards” with “XXX” written in each color (blue, green, orange, yellow, red, and purple). For example the word “green” would be written in yellow, orange, red, blue or purple. The system obtained a built in timer and a data sheet in which filled each component after each trial
Experimental Design Within this experiment, the independent variable (IV) consisted of three interference levels. The first level was the “XXX”, the second level was the color and ink matched combination, followed by the third level of mismatched ink and color combination, the mismatched condition. The dependent variable (DV) consisted of the response time in seconds. It was measured by the number of milliseconds it took for the participant to press the letter on the keyboard that represented the color set before them. The operational definition of response time was defined as the time measured from when the word was flashed to the center of the computer screen to the time it took the participant to press the appropriate key on the keyboard that corresponded to the color of the word presented. For this experiment, the experimental design is that of a within-subjects design with a counterbalanced order of conditions (ABCCBA). The Null hypothesis was believed that the means of both reaction time and the number of accuracy of the students after each condition would not differ between the conditions; no difference in reaction times or number of errors as the level of interference increases. The Alternative hypothesis was that at as the level of interference increases, reaction time will increase as well as would the number of errors present.
Procedure
For this experiment, the order is as follows: A) XXX presented in all colors; XXX B) Matched color/word combination; Congruent C) Mismatched color/word combinations; Incongruent C) Mismatched color/word combinations; Incongruent B) Matched color/word combination; Congruent A) XXX presented in all colors; XXX Students were placed in front of a 24 in mac computer in which they accessed the website http://psych.hanover.edu/JavaTest/CLE/Cognition/Cognition/Stroop.html. There they selected the appropriate conditions for which they will be testing at the given time (i.e. congruent, incongruent, or XXX) followed by the checking off of all the colored boxes offered, unchecking the limiting response option, selecting the “respond to color” option and “center location” for every trial. The number of words in the condition should be changed to 100 words as well as the font size change to 30. Once the conditions are set up, the participants run a serious of practice trials for each condition at least once in order to understand and practice that which will be tested. Once each condition is practiced once, the participant is ready to begin the experiment by pressing the space bar of their keyboard. The participant will now pay attention to the color of the words in which will appear in the center of the screen and as quickly as they can, use their hands to mark off the first letter of the color shown (i.e.: Yellow will be marked off as a Y). This procedure is then to be repeated for all six trials following the ABCCBA sequence of conditions. After each trial and condition is tested, the program will summarize the results of your trial to which you will then record the accuracy and the duration down into the participants own data sheet. Once all data is obtained, a one-way repeated ANOVA and Tukeys HSD will be conducted in order to obtain the analysis of variance and significant differences between the conditions respectively.

Results A within participants, one-way ANOVA was conducted to compare the effect of interference level (congruent, incongruent, XXXX) on reaction times. There was a significant effect of interference level on reaction time F (2, 32) = 64.52, p < .0001. Post-hoc comparisons using the Tukey HSD test indicated all means were significantly different from one another; mean reaction time in the congruent condition (M= 890. 27 ms, SD=248.87 ms) was fastest, followed by the XXXX interference condition (M = 1074.28 ms, SD = 202.61 ms) and the incongruent condition (M = 1274.76 ms, SD = 247.40 ms). A within participants, one-way ANOVA was conducted to compare the effect of interference level (congruent, incongruent, XXXX) on the accuracy for naming colors. There was a significant effect of interference level on accuracy for naming colors, F (2, 32) = 6.8, p = .003. Post hoc comparisons using the Tukey HSD test indicated the accuracy for naming colors in the incongruent condition (M= .98, SD= .02 ) was significantly lower than in the congruent conditions (M = 1.00, SD = .01 ) . Comparisons between the XXX (M = .99, SD = .01) and the other two groups were not statistically significant.
Discussion
After completion of the experiment and analysis of the results, the reaction time and the number of errors that were made were found to be longer and larger for the unmatched word and ink condition rather than the other two conditions of matching words and color and matching symbols with color. The original alternative hypothesis stated that as the level of interferences increase the number of errors will as well. The results, as shown in Figure 1 and Figure 2, concluded that the null hypothesis can be rejected while the alternative is accepted; that at least one of the conditions have differed from that of the other conditions. These results correspond to those found by Stroop (1992). Within his experiment, he found that the higher the inference level the greater the amount of errors would be made. Limitations of our experiment may include the participants having learned the technique of the experiment after running several practice trials before starting the experiment. Other variables may include the inconsistent method of pressing the keys on the keyboard (some may have had their fingers already placed on the keys of the keyboard) or their method of completing the task by saying the words out loud. These individualistic methods may have altered the overall results in that they may have aided the participants with completing the tasks more efficiently than others who were not using the same techniques. There was no consistency amongst all the participants on the method; it varied for each individual. According to Stroop (1992), other researchers have concluded from several experiments that the source of interference is found in the materials themselves. The significance of the findings during the experiment reveals that the interference levels significantly cause a slower reaction time and greater number of errors. In conclusion, the experiment depicts how interference affects ones reaction towards something.

Reference
Stroop, J. R. (1992). Studies of interference in serial verbal reactions. Journal of Experimental Psychology, 121, 15-23.

Figure 1. This graph represents the participants mean response time in milliseconds as a function of condition (the three interference conditions).

Figure 2. This graph shows the accuracy of the individuals as a function of the condition presented (three levels of interference)