Graphical interfaces

If scripting scares you off, don’t run too far away. You can achieve a good deal using either PsychoPy Builder or OpenSesame, two graphical interfaces in rapid development. The accessibility comes at a price, though: you have to give up some of the almighty control that comes with scripting.

In general, I’d say that the graphical interfaces are great for casual experiments, for teaching and for non-coders who consider using some commercial solution. If you want milliseconds precision and/or interactions with external equipment, go for scripting.

PsychoPy Builder vs. OpenSesame

This is my take on the relative strengths of Builder and OpenSesame. I would use PsychoPy by default and OpenSesame in the following cases:

  • Form-like input is required (multiple choice, input text fields etc.). OpenSesame contains this out of the box where you have to add a Code Component in Builder at the moment.
  • A visual canvas (the sketchpad) in the editor where you can put in stuff manually. In Builder, you only get to see the actual stimulus appearance when you run the experiment.
  • If the experiment contains only one or two loops and a very simple procedure within the loop, like presenting a single word or picture and collecting a response. OpenSesame’s timeline hierarchy becomes non-transparent if your trial-procedure contains multiple stimuli and events. Also, looping over loops in OpenSesame is less flexible in my experience than in the Builder.


You can find video introductions on the OpenSesame website. Jon Peirce created a nice video tutorial on building a stroop experiment in Builder. We’re going to extend this design, adding a loop around the loop and some extra stimuli. First in Builder and then in OpenSesame, just to see the relative strengths and weaknesses of the two interfaces.


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