Lab Report: The Stroop Effect

The ‘Stroop Effect’ was first introduced in 1935. It originated from the theory of automatic processes. It is clear that some processing activities become automatic as a result of prolonged practice eg. Typing, driving, etc. Automatic processes therefore are fast, require no attention and are unavoidable. Stroop believed that there was some evidence that word identification may be a form of an automatic process. In the experiment participants had to name the colours in which the words were printed as rapidly as possible. It was shown that naming speed was slowed when the words were conflicting colour names.

The ‘Stroop Effect’ suggested that the word meanings were extracted when the participants were not attempting to process it. The original ‘Stroop Effect’ was illustrated using colour. Flowers et al. developed another version of the ‘Stroop Effect’ in 1979. Instead of using colour the new version was illustrated using numbers. The task was to say aloud the number of characters, which appeared. These characters appeared in both numerical and image format. Therefore the participants found it very difficult to resist saying the number they saw rather than the number of characters which appeared. The current study was a partial representation of the Flowers et al. study.

Method:

The experimenter first of all instructed the participants to turn on the computer. The participants were then asked to open the necessary file. Instructions appeared on the screen describing to the participants what was going to happen next. The participants were instructed to place four fingers on the keys 1 to 4 along the top of the keyboard. Participants were then told to illustrate using the numbers 1 to 4 how many figures appeared on the screen at a time and not to be distracted by the shape of the figures. The figures were displayed in both numerical and pictorial form. The participants were then instructed by the experimenter to record their individual results.

Results:

In order to calculate the results a binomial test was used. A binomial test is one, which uses two categories. In this case the categories used were the number of participants who were faster at * and the number of participants who were faster at numbers (view table 1). ‘N’ the number of participants was 24 and ‘k’ the least occurring alternative was equal to 1. The statistical tables were then consulted and the results were found to be consistent. The result of the experiment was very significant with P (the level of significance) equal to 0.000.

Discussion:

The current study was a partial representation of the Flowers et al. study conducted in 1979. It was clear from the results that the participants hesitated when numbers rather than figures appeared on the screen. In fact 23 of the participants were quicker at identifying the * where as only 1 participants was quicker at identifying numbers. Even though the result of the experiment was significant there were some limitations. Most of the participants had to share a computer. This meant that the participants were put under pressure as they were being watched during the course of the study. Also due to the lack of computers a lot of the participants were talking while the experiment was being conducted. This made it hard for the participants to concentrate. Noise could also be heard coming from the hall which once again lead to a lack of concentration. If this study was to be conducted again the following changes should be made. Either the participants are called in one at a time or there should be a relevant amount of computers so that each participant would have their own computer. In future study the experiment should also be conducted in a sound proofed room in order to minimize the number distractions.

References:

Stroop, J. R. (1935). Studies of interface in serial verbal reactions. Journal of Experimental Psychology, 18, 643-622.

Flowers, J. H., Warner, J. L., & Polansky, M. L. (1979). Response and encoding factors in ignoring irrelevant information. Memory and Cognition, 7, 86 – 94.