The Stroop Effect is one of the most widely employed tasks in cognitive psychology. Originally designed by J.R Stroop (1935), it refers to the interference that an automated skill such as reading causes when carrying out a non-reading task.

In the original Stroop task (Stroop, 1935), participants were shown a list of colour words (e.g. red, green, blue, yellow) or symbols (like XXXXX), printed in different coloured ink. They were then asked to name the colour of the ink, and the experimenter measured how long it took them to finish naming all the colours on list. Stroop found that participants took a lot longer to name the colours on the list  where the colour words and the colour if the ink were mismatched (incongruent) than when they were congruent, or when the stimulus was a list of symbols (Stroop also included trials where participants were asked to read colour words printed in black ink – you can read the original paper here):

Sometimes researchers would divide the time it took a participant to read the list by the number of items on the list to get an approximate reaction time for individual words (See MacLeod, 1991, for a review of over 400 studies of the Stroop effect in the first 50 years since the original publication). Nowadays, it is common to administer the Stroop task on computer, which allows the researcher to present one word at a time and get highly accurate reaction times in millisecond range for each stimulus.

The Psychology Lab can offer a a ready-to-go Stroop task built in SuperLab – software for building psychology experiments and collecting data – which you are welcome to use in your study. The Lab’s version of the Stroop task takes up to 10 minutes to complete. The experiment consist of:

• 24 practice trials:
  • 8 trials where participants are asked to classify the font colour of “XXXXX” symbols
  • 8 trials where participants are asked to classify the font colour of non-colour words, such as tree, desk, shoe, etc.
  • 8 trials where participants are asked to classify the font colour of colour words, such as blue, green, red, and yellow.
• 120 experimental trials where participants are asked to classify the colour of colour words. Half of the trials are congruent condition and half are incongruent condition. Congruent and incongruent trials are presented in random order, with the option for a short break after 60 trials.

Participants can respond to stimuli by using keys of a computer keyboard, or one of the response pads with coloured keys.

The Stroop task available in the Psychology Lab is highly customisable. You can adjust the number of trials presented, the instructions shown to participants as well as the type of stimuli. Here are some examples of how the Stroop Task can be modified:

• Emotional Stroop effect (see Frings et al., for a recent review) refers to a phenomenon where participants are faster in classifying ink colour of neutral words, as opposed to emotional words such as attack, death, sad, etc. This effect has be utilised in studying social anxiety (Askew, Hagel & Morgan, 2015), emotion regulation (Kappes & Bermeitinger, 2016), depression (Mitterschiffthaler, 2008), or PTSD (Cisler et al., 2011).
• Metcalf and Pammer (2011) assessed attentional bias in massively multiplayer online role-playing gamers by including game related words in the Stroop task
• White (2009) used added words related to sociability to the Stroop Task to explore whether salient gender identity activates gender stereotypes among student population.

We can offer advice or training on how to modify the experiment to suit your needs. Contact the psychology technicians if you’d like to learn more about how the lab can help with your study.

 

References

Askew, C., Hagel, A., & Morgan, J. (2015). Vicarious learning of children’s social-anxiety-related fear beliefs and emotional stroop bias. Emotion, 15(4), 501-510. 10.1037/emo0000083

Cisler, J. M., Wolitzky-Taylor, K. B., Adams, T. G., Babson, K. A., Badour, C. L., & Willems, J. L. (2011). The emotional stroop task and posttraumatic stress disorder: A meta-analysis. Clinical Psychology Review, 31(5), 817-828. 10.1016/j.cpr.2011.03.007

Frings, C., Englert, J., Wentura, D., & Bermeitinger, C. (2010;2009;). Decomposing the emotional stroop effect. The Quarterly Journal of Experimental Psychology, 63(1), 42-49. 10.1080/17470210903156594

Kappes, C., & Bermeitinger, C. (2016). The emotional stroop as an emotion regulation task. Experimental Aging Research, 42(2), 161-194. 10.1080/0361073X.2016.1132890

MacLeod, C. (1991). Half a century of research on the stroop effect – an integrative review. Psychological Bulletin, 109(2), 163-203. 10.1037/0033-2909.109.2.163

Metcalf, O., & Pammer, K. (2011). Attentional bias in excessive massively multiplayer online role-playing gamers using a modified stroop task. Computers in Human Behavior, 27(5), 1942-1947. 10.1016/j.chb.2011.05.001

Mitterschiffthaler, M., Williams, S., Walsh, N., Cleare, A., Donaldson, C., Scott, J., & Fu, C. (2008). Neural basis of the emotional stroop interference effect in major depression. Psychological Medicine, 38(2), 247-256. 10.1017/S0033291707001523

Stroop, J. (1935; 1992). Studies of interference in serial verbal reactions (reprinted from journal experimental-psychology, vol 18, pg 643-662, 1935). Journal of Experimental Psychology-General, 121(1), 15-23.

White, J. B., & Gardner, W. L. (2009). Think women, think warm: Stereotype content activation in women with a salient gender identity, using a modified stroop task. Sex Roles, 60(3), 247-260. 10.1007/s11199-008-9526-z