Title of Your Lab Assignment

Running head: STROOP EFFECT 1 1

Stroop Effect

by Keegan Moser 201006272 and Roberta Carson 201005319

A laboratory report presented to J. Wright in Psychology 220 Cognitive Psychology

Department of Psychology St. Francis Xavier University

November 29, 2012 STROOP EFFECT 2

Abstract

The purpose of the present study was to investigate how either differing or matching the font colour of a stimulus word to the colour named by the word affects reaction time when identifying the font colour of the word. Using the CogLab Online Laboratory 2.0, 78 cognitive psychology students participated in a Stroop effect experiment. During each trial, the task of the participants was to identify the font colour of a word. The words alternated between the names of three colours over 45 trials. It was predicted that the font colour would influence the reaction times. As expected, a significant effect on reaction time was observed, t(77) = -17.96, p < .05. The process of automated behaviour is discussed. STROOP EFFECT 3

Stroop Effect

When certain human behaviours are repeated frequently over long periods of time, behaviours may become automated. Automated behavior does not require conscious control.

This process of automation is important because it allows frequent behaviours to be carried out unconsciously, while attention is diverted towards other, less familiar tasks (Wheatley and

Wegner, 2001). Psychologists who seek to study automatic behavior frequently do so by creating an experimental environment in which automatic behaviors, if present, will interfere with conscious behaviors. Perhaps the most well-known and most frequently repeated of these experiments was the 1935 experiment performed by J.R. Stroop. Stroop’s experiment involved presenting subjects with the names of colours, in various colours of ink. Subjects were asked to either read the word, or state the color ink it was printed in. Stroop found that subjects required more time to state the colour of the ink than to read the word (Stroop, 1935). This study has been repeated many times, all with similar results, and has led psychologists to conclude that in such cases, reading has become an automated process, one that interferes with the ability of participants to state only the colour of the text.

While the Stroop Effect tends to hold true, there are other factors that influence the degree of interference that occurs, as numerous other studies have indicated. Braet et al. (2011) demonstrated that there is a positive correlation between reading skill of a language and amount of Stroop interference produced. This suggests that as a language is learned, the reading of the language becomes an increasingly automated process. Research conducted by Coderre et al.

(2008) revealed a similar degree of Stroop interference between two writing systems of the same STROOP EFFECT 4 language. However, it revealed that the two writing systems were processed differently. This is important because it suggests that the Stroop effect (and automation of reading) is not exclusive to writing systems that are confined to syllabic symbols. Lastly, research performed by Goldfarb,

Aisenberg and Henik (2011) provided insight into how the Stroop effect can be reduced. They used social priming with the concept of dyslexia, to successfully reduce the amount of interference. This is important because it suggests that automatic behaviours are more successfully reduced by using other automatic behaviours, rather than conscious behaviours..

The purpose of the present study is to investigate the Stroop effect masking in a computerized task. CogLab’s online laboratory will be used to access an application that creates presents stimuli similar to those found in the original study by Stroop (1935). The independent variable of this study is whether the font colour and the word name correspond or not the dependent variable is participants’ reaction times to the stimuli presented. The methodology of this experiment is similar to that used by Stroop in that in both experiments, participants are presented with stimuli consisting of the names of colours in varying font colours and must respond to them. In contrast to previous studies of the Stroop effect, this study was performed via an online application which automatically records both individual and group data.

Because of the results of previous experiments in this field, it is hypothesized that participants will take longer to respond to stimuli when the name of the colour does not correspond to the font colour than when they do.

Method

Participants STROOP EFFECT 5

Participants were 78 students from a cognitive psychology class at Saint Francis Xavier

University, who participated as part of their lab requirement.

Apparatus

A Wadsworth CogLab 2.0 Online Laboratory task called Stroop Effect was used in the present study. Participants completed the task on iMac computers in a computer lab. The task was accessed through the CogLab webpage and opened in its own window on the computer screen. The task window was entirely black apart from the stimuli used in the tasks, which were green, red or blue, the point of fixation, which was white, and the instruction text which was also white. The stimuli were the words ‘Red’, ‘Green’ or ‘Blue’ in approximately size 26pt . Each trial consisted of a presentation of a stimulus just above the point of fixation. At the top of the screen, the instructions “Identify the color of the font and ignore the name of the word. Press the h key for red, the j key for green, and the k key for blue” appeared. The instruction text was white, Arial, and approximately size 14pt. Participants used the keyboards provided in the lab to select their responses during the experiment.

Procedure

Participants were seated at iMacs in the computer lab. They first entered their individual log-in information to access the CogLab experiment. They then read the CogLab Online instructions for the Simon task, which appeared in their own dialogue box. The instructions informed them about which keys on the keyboard to select depending on which colour the font.

Participants pushed the space bar when they were ready to begin the first trial. For each of the 45 trials, participants were presented first with the fixation point, and then, approximately one second later, a word appeared onscreen just above the fixation point. Participants selected in their STROOP EFFECT 6 own time which colour the stimulus word’s font was. If the stimulus word was red, they selected their response by pushing the ‘h’ key. If the stimulus word was green, they pushed the ‘j’ key. If the stimulus word was blue, they pushed the ‘k’ key. Once their response was entered, text appeared above the fixation point reading either “correct” if the participant had selected the correct colour, or “incorrect” if the participant had selected the incorrect colour. Text appeared below the fixation point instructing the participant to press the space bar to begin the next trial.

Once the participant pushed the space bar, the next trial began immediately and a new stimulus square appeared. If the participant selected a colour before the stimulus was present, text appeared reading “Too early, wait for the stimulus”.

The independent variable of this study was whether the font colour and the word name corresponded or not. The dependent variable was participants’ reaction times to the stimuli presented. Using this information, means and standard deviations were calculated for the reaction times in each condition of the experiment.

Results

When the name of the colour and the font colour were the same, the average response time was 765.5393 ms (SD = 210.74277 ms), whereas when the name of the colour and the font colour were different, the average response time was 826.2637 ms (SD = 212.84798 ms). Figure

1 demonstrates the difference between the two groups. There was a significant difference in reaction times between the two conditions, t(77) = -17.96, p < .05.

Discussion

The results of the current study support the hypothesis. It was hypothesized that reaction times would be longer when the color of the font differed from the name of the word presented STROOP EFFECT 7 as the stimulus than when the font colour and word name were the same. This prediction is supported by the obtained results because a significant difference was found to exist between the reaction times in the two conditions. Close examination of Figure 1 shows that the average reaction time when the font colour differed from the word name was, on average, over 80 ms longer than when the colour and word were the same.

The present study supports to the ideas proposed by Stroop (1935). As this experiment did not measure the participants on any factors such as gender, reading ability or any other factors, no other conclusions are able to be drawn from the data collected. This limited usefulness of the present study, as this experiment has been replicated by many psychologists already. Future research would benefit from adding another variable to the experiment, preferably one previously unexamined in relation to the Stroop effect.

A broader application of the present study is that more support is given to the theory that reading is an automatic process that is capable of interfering with conscious processes, such as the selection of colours. STROOP EFFECT 8

References

Braet, W., Noppe, N., Wagemans, J., & de Beeck, H. (2011). Increased Stroop interference with

better second-language reading skill. The Quarterly Journal Of Experimental

Psychology, 64(3), 596-607. Retrieved November 27, 2012, from

http://www.tandfonline.com.libproxy.stfx.ca/doi/pdf/10.1080/17470218.2010.513735

Coderre, E. L., Filippi, C. G., Newhouse, P. A., & Dumas, J. A. (2008). The Stroop effect in

kana and kanji scripts in native Japanese speakers: An fMRI study. Brain And

Language, 107(2). Retrieved November 27, 2012, from

http://www.sciencedirect.com.libproxy.stfx.ca/science/article/pii/S0093934X08000187

Goldfarb, L., Aisenberg, D., & Henik, A. (2011). Think the thought, walk the walk—Social

priming reduces the Stroop effect. Cognition,118(2), 193-200. Retrieved November 27,

2012, from

http://www.sciencedirect.com.libproxy.stfx.ca/science/article/pii/S0010027710002635

Stroop, J. R. (1935). Studies of Interference in Serial Verbal Reactions. Journal of Experimental

Psychology, 18, 643-662. Retrieved November 27, 2012, from

http://psychcentral.com/classics/Stroop/

Wheatley, TP, Wegner DM. 2001. Automaticity in action. International encyclopedia of the

social and behavioral sciences. (N.J. Smelser, P.B. Baltes, Eds.).:991-993., London:

Pergamon STROOP EFFECT 9

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m 800 (

e 790 m i T 780 e s

n 770 o p

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R 750 740 730 Name and font the same Name and font different

Condition

Figure 1. Reaction time to stimulus as a function of the condition of the presented stimulus.