Psychology 2020L – Stroop Effect Laboratory

Due Feb 13 (A2 & B2) & Feb 15 (C2)

In a classic psychological study, Stroop (1935) conducted an experiment to determine if the brain processed different types of information faster than other types of information. In particular, he was interested in determining if automatic processes would interfere with more deliberate processes required by the task. To examine this idea, participants in one experiment were each presented with two conditions that involved naming the colour in which the stimulus was presented. In one condition, participants were shown a series of squares presented in different colours. In the other condition, the participants were presented with a list of colour names displayed in a different colour (e.g., the word RED presented in blue ink). Stroop found participants took much longer to name the colour in which the colour word was presented, relative to the coloured squares. He proposed that this effect arises because word reading is fast and automatic and as a result, it interferes with colour naming – the more deliberate processing required by the task. Since this initial demonstration, the “Stroop effect” has been reported in a number of different variants of this task, showing that this effect is highly robust.

For this lab, you and a partner will be conducting a modification of the Stroop (1935) experiment. You will be asking the question, are reading and naming deliberate processes or do they occur automatically? To conduct this experiment, you may use the colour naming version of this task demonstrated in class, you may use Elmes, Kantomwitz and Roediger’s (1989) variant of this task using digits (on ACME) or you may come up with your own type of Stroop experiment. If you do decide to design your own experiment, please come and talk to me (Karmen) first. Make sure that you think of your hypotheses before you start.

Your experiment will be a repeated measures design (the same participants will be tested on all levels of the independent variable). Also, you must have at least 3 levels of the independent variable (type of list) in your experiment and make sure that you counterbalance the presentation order of the lists (subject 1 – 1,2,3; subject 2 – 1,3,2; etc.). There is a table on ACME that provides an example. The dependent variable is the time it takes to read a list (in seconds). You may also record errors. Since you will be recording time, you will need a stopwatch of some kind. You will also have to decide on the instructions you would like to give the participants (e.g., fast, fast and accurate, etc.)

Once you have ensured that your experiment is ready to go, choose a convenient sample of 12 participants (e.g., people in residence, the SUB, etc.). Make sure to get informed consent from all participants prior to their participation in the study and provide them with all the necessary information typically required of informed consent (e.g., participation is voluntary, confidentiality, etc.). Make sure that you use the same instructions for all participants in both recruiting and in running the experiment. It is also critical that you accurately keep track of the time for the list that the participant is reading at the time – since you have to counterbalance the order of presentation, it is important that you report the appropriate time for the appropriate list. Following completion of the experiment, thank the participant and debrief them (i.e., explain your hypotheses, where they can contact you for further information etc.). Remember, do not violate any ethical guidelines!

Once you have collected your data, you will analyze it using Analysis of Variance (ANOVA) – we will discuss this more thoroughly in class.

Following your analyses, you will write up a full APA style paper. You must provide an Abstract, as well as Introduction, Method, Results, Discussion and Reference sections. You need a minimum of 3 articles for your introduction. The Stroop (1935) paper is on reserve in the library. For the Method section, be sure to include the Participants, Materials and Procedure subsections and all necessary detail for each of these sections. You can discuss your counterbalancing procedure in the Procedure subsection. For the Results section, make sure to include all appropriate analyses and to report the values in the write up in APA format. Finally, in the Discussion section, be sure to discuss the implications of your findings, what factors may have influenced the results, ways to improve the study, how this relates to the original Stroop effect, etc.