A Report on The Evaluation of The Stroop Effect

Introduction

The Stroop Colour and Word Test effect on its basis is one of the most well-known and long-lasting phenomena in all cognitive science and psychology. Having been first reported by John Ridley Stroop in 1935, the phenomena explains the degree of difficulty people have with naming colour of the ink rather than the word itself (Stroop, 1935). More specifically, it assesses the ability to inhibit cognitive interference, which occurs when the processing of a stimulus feature affects the simultaneous processing of another attribute of the same stimulus (Scarpini & Tagini, 2017). Since the early beginnings of experimental psychology, it was identified that clear words are faster to read compared to objects or their properties are to name. A study conducted in 1886, introduced the concept of automaticity to cognitive science which explained that word reading counts as an unconscious automatic process due to extensive practice (MacLeod, 1991). Under this concept, people cannot abide by with an instruction of not to read because reading in itself cannot be turned on and off. Hence why it is guaranteed that incompatible words will cause interferences when attempting to name their printed colours. In the following report, subjects are required to read three different tables of information as fast as possible. Two of them are represented as a congruent condition in which the participants are asked to read the names of colours in text printed in black ink and name different coloured blocks without text. Conversely, the last test, is the Stroop effect test, where coloured words are printed in an inconsistent colour tone. Thus, this is deemed as the incongruent condition as the participants are required to name the colour of the ink instead of reading the text. While this experiment is mostly used for the purposes of measuring the ability to inhibit cognitive interference, similar research also found its applications to measure other cognitive functions such as attention, speed of process and cognitive flexibility.

In the present report, two main hypotheses will be analysed testifying the three experiments. Hypothesis-one predicts the completion of the Word Task being significantly faster than the Coloured-block Test. The other hypothesis states that participants will take longer to complete the Stroop Task than the Coloured-block Task. The focus of the study is on the completion speed of each task and the various cognitive functions that influence it.

Methods

Participants

A select number of 138 (N = 138) university students enrolled in PY1102 subjects, with a gender split of 40 males and 98 females was qualified to participate in the research. The experiments were conducted during their allocated tutorial hours. The mean (M) value of the age of participants was calculated to be 24.19 years along with a standard deviation (SD) of 9.54 years.

Materials

A stimulus and a response card along with a stopwatch were used to conduct the experiment. The given stimulus and response card contained exactly the same instructions and consisted of three different tests that needed to be completed.

Procedure

The experiment consisted of three separate tests that was conducted to measure consistency and the speed of which each task was completed in comparison with each other. All three experiments were used to also identify cognitive functions in terms of executive inhibition of prepotent responses and certain interferences that occurred. The first sequence of assessment was based on a word reading test. Participants were provided with a paper consisting of different colours in basic text format. The instructions were given that each participant had to read out the list of words aloud as quickly as possible, starting from left to right and top to bottom. A separate response sheet was used by the experimenter to manually score the amount of errors and the time it took upon completion.

Following the experimental paradigm provided, the second part of the experiment instructed the participants to identify and name coloured blocks without text in quick successions. The test followed similar steps to task one, but with an obvious change of stimulus provided. Again, a separate response sheet was used to track the progress and identify errors that occurred.

The last part of the experiment consisted of the classic colour-word Stroop task. The task was presented on the paper and showed successive words of red, blue, green and yellow in all the four different font colours on a white background. Each trial was presented as either congruent (e.g “red” written in its original colour) or incongruent (e.g “green” written in a different colour). Participants were tasked to identify and pronounce the colour of the ink and ignore the meaning of the present word. The results were scored accordingly to the previous two experiments and any errors that occurred was resolved during the process.

Results

The descriptive values identified in the results showed that the Word task (M= 7.62, SD=1.61) was completed at a faster rate than the Colour-block task (M=9.12, SD=2.03) and the Stroop task (M=17.12, SD=5.47). The inferential comparison of the Word task v. Coloured-block task (t (df)= -9.39, p-value=0.000) and the Colour-block task vs Stroop task (t (df) = -19.34, p-value=0.000) presented a constant p-value regardless of any differences. The degrees of freedom (t(df)) value however, presented the indicator that the coloured-block test when in comparison with the word test achieves a figure far greater when it’s conversely in contrast with the Stroop task.

Discussion

Upon completion of the experimental phase, the results along with previously reviewed studies came out in support of the given hypotheses. The parameters of speed and accuracy of the performance were both underlined through all three experimental designs, thus highlighting no methodological conflicts. In support of the first hypothesis, as predicted, the results of the Word Task were found indicating a lower time interval compared to the Coloured-block Task (p < 0.001). Hypothesis two was also supported as the results showed that the Coloured-block Task was completed substantially faster than the Stroop Task (p < 0.001). To predict the outcome of the hypotheses, inferential statistics were used to make inferences based on the relations found in the sample. Descriptive statistics was also used to validate and compare the results of the sample size through the calculations of the mean value along with standard deviation.

According to the studies with Italian normative data conducted by Amato and Caffarra, the results were identified to be influenced by attentional functioning and the general cognitive efficiency of the participant. In regard to the Stroop task, slowing to a response conflict was identified to be due to failure of selective attention or lack in cognitive efficacy. All participants had to process selectively a specific visual stimulus while blocking out the automatic processing of reading in order to solve the task in hand. This creates an interference which confuses the brain and creates a conflict, forcing a decision without much evaluation (MacLeod, 1991). Interference also occurs due to human memory, where previously learnt information stored as a memory or thought conflict with new information. Trying to identify and interpret this new stimulus becomes difficult due to the speed in which the brain recollects and process old information (MacLeod, 1991). Hence, the Stroop task was identified to be harder to complete compared to the other two. Conversely, the Word task is regarded to be the easiest, as the stimulus applied is not perplexing and it uses an automated process of general cognition to complete the task at a faster rate.

Certain recorded scoring techniques impede an exhaustive description on the performance of individuals and limit the validity of the practice (Amato et al., 2006). For instance, only the reading time was recorded appropriately, while accuracy was examined by the experimenter which in fact implies a possibility for human error. Participants could easily report an incorrect description of the correct answer and due to the incongruous condition and despite poor performance the experimenter could have easily mixed up the results as well. Such behaviour indicates a chance of failure to maintain consistency of the experiment, even if the participants properly completed the task. In light of the previous analysis, a different scoring method for all three tests is recommended that fills the two main requirements. Firstly, following the original methodology both accuracy and speed must be tested but independently of each other through a computer-generated process. This eliminates the chance of human error and validates the integrity of the study. Secondly, a global index must be generated in the near future, so different levels of performance can be generated through a comparison. Finally, further research on the topic of study should be mentioned and a review on the methodology of the experiments should be testified. This will help shape way for any future research about the cognitive basis of psychology.

Works Cited

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