In Experiment 1 of the original Stroop Task, subjects were given a word list of color words. Each word was written in an incongruent color and they were asked to name the color of the ink the word was written in. Evidence from this experiment shows that it takes longer to name the ink color than to name the word itself (MacLeod 1991). Hundreds of variations have been performed with the Stroop Task, including a manual matching version by Taylor and Clive (1983). Auditory stimuli have been introduced in different variations, but none have been paired with the manual matching task. In this experiment, an auditory stimulus was introduced while subjects performed the manual matching Stroop Task. The hypothesis was that a significant interference would occur in the process systems of the brain.
Subjects
The subjects in this experiment were 21 Alma College Students (13 females and 8 males) between the ages of 18 and 23.
Apparatus/Tools
The five colors used in this experiment were blue, green, yellow, brown, and red. Four decks of fifteen cards each were used. The decks were comprised of color patches, color words in their corresponding ink colors, color words in incongruent ink colors, and neutral words (i.e. house, book, chair). Each of the five bins used to seperate the decks of cards were labeled with one of the experimental colors written in its congruent ink color. Two different auditory stimuli were introduced to the subjects using a tape player with head phones. One side of a tape was comprised of neutral words and the other side was comprised of the color words used in the experiment.
Procedure
Each subject performed three trials in which they sorted the sixty cards according to the ink color they were written in and matched them to the appropriately labeled bins. The bins were placed side by side and were made deep enough so that when a card was placed inside the bin, the subjects were no longer able to see the card. After each deck of cards were sorted, the bins were rearranged in order to avoid a learning effect. The three trials consisted of the neutral word stimulus, the color word stimulus and a control group which involved no auditory stimulus. Subjects were asked to repeat out loud each word they heard while they manually sorted the cards. The amount of time it took for each subject to complete each trial was recorded and compared.
As seen in all four graphs (Figures 1-4), there was little significant effect between the control group and the trials involving the auditory stimuli. It took subjects about 13 to 15 seconds to sort most of the decks under the control trial. Under the trials with the stimuli, it took subjects about 16 to 17 seconds to sort the decks. Subjects took the longest amount of time with the color words in the different ink colors under the trials with the auditory stimuli. Because little statistical significance was found, it can be said that there was only a slight Stroop effect.
The small difference that was found between the control trial and the trials involving the auditory stimuli could be a result of effects from doing multiple tasks at one time. In other words, it takes subjects longer to do two different things at once. However, through the authors' observations, subjects did seem confused when first introduced to the color word stimulus while sorting the color patch cards and the incongruent color word cards. Even though the bins were rearranged after each trial and the decks were presented in different orders, results still seemed to show a learning effect. Subjects reported that they had a tendancy to block out the auditory stimulus and the words written on the cards. This may support the idea that these different tasks were run by seperate parts of the brain, and thus were able to be done independent of each other.
Daniel (1969). Performance in an interference test and some changes in the vegative functions. Psychological Abstracts, 44, 267-271.
Dyer & Severance (1972). Effects of irrelevant colors on reading of color name: A controlled replication of the "reversed Stroop" effect. Psychonomic Science, 28, 336-338.
MacLeod, Colin M. (1991). Half a century of research on the Stroop effect: An integrative review. Psychological Bullitin, 109, 163-193.
Taylor & Clive (1983). Two forms of the Stroop test. Perceptual and Motor Skills, 57, 879-882.
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