Week 4: Programming a Stroop experiment in JsPsych

How to program a basic Stroop experiment in JsPsych, and some considerations of various design parameters.

Pre-requisites:

Have followed along from the previous posts.

Part 1: Basic Stroop

Part 2: Using a script to generate a stimulus array

Concepts to cover

I’ll cover the following concepts in the screencast and show how I am using software as I go along.

• What is a Stroop Experiment?

Readings:

Logan, G. D., & Zbrodoff, N. J. (1998). Stroop-type interference: Congruity effects in color naming with typewritten responses. Journal of Experimental Psychology: Human Perception and Performance, 24(3), 978–992. https://doi.org/10.1037/0096-1523.24.3.978

MacLeod, C. M. (1991). Half a century of research on the Stroop effect: An integrative review. Psychological Bulletin, 109(2), 163. https://doi.org/10.1037/0033-2909.109.2.163

• Programming a basic Stroop experiment in JsPsych from scratch

• Additional considerations

  • Elements around the main experiment
    • welcoming people, explaining the task, making sure they understand, giving feedback, debriefing them.
  • Design considerations:
    • different response modalities (button press vs. typing vs. voice key)
    • Proportion manipulations
    • sequence manipulations

Links to example code

Remember, you can view the source code from github repository for this website.

Basic stroop example

Second Stroop example

Assignment

1. Demonstrate that you can get the Stroop tutorial example working on your Quarto blog. Feel free to attempt writing your own version of a Stroop experiment from scratch, this is the best way to learn. For this course, and at this stage, it is also fine if you obtain my example code and demonstrate that you can get it working on your quarto blog (e.g., produce a link that runs the experiment.)

2. Brainstorm a manipulation that you think might change the size of the Stroop effect. For example, would making the color words bigger make it even harder to ignore the words, and therefore produce a larger Stroop effect (compared to trials where the words were much smaller and harder to read, and therefore easier to ignore)?

3. Produce a version of the Stroop experiment that deploys your manipulation. In the example above, you would need to have some trials where the word appears in a small font and others where it appears in a large font.

Advanced

We will cover data analysis next week, but if you want to find out whether your manipulation worked, then you will need to analyze your data in each condition. See if you can find a way to do this. Did your manipulation succesfully cause a change in the size of the Stroop effect?