34  Miscellanea

34.1 PsychoPy processes components from top to bottom

Within a routine, PsychoPy processes components from top to bottom. If you would like to draw a star¹ on top of a square, the square needs to come first, followed by the star:

34.2 Skipping routines

Sometimes you might want to not present a routine. In PsychoPy, this can be done by using continueRoutine in a code component. For example, you might want to present “Too slow!” feedback only if participants took more than 1.5 s to respond. This can be achieved with a feedback routine that has the following code component in the “Begin routine” tab:

if response.rt > 1.5:  # if the response was slower than 1.5 s
    continueRoutine = True  # present the feedback routine
else:
    continueRoutine = False  # do not present the feedback routine

Below the code component, the feedback routine would also need a Text component that displays the text “Too slow!” if the routine is presented. This text could be set to constant as it never changes.

For testing purposes, it is often convenient to skip multiple routines (e.g., if you don’t want to run the practice trials, and instead want to run the main trials straight away). This can be achieved by adding a loop around these routines and setting “Num. repeats” for this loop to 0.

34.3 Copying and pasting routines and components

In Section 25.4, we briefly mentioned that the “Experiment” menu in the menu bar gives you the option to copy and paste routines:

To copy a routine, click on the routine’s tab (if it is not already selected), then click on “Experiment” and “Copy Routine”. Finally, click on “Experiment” and “Paste Routine”.

It is also possible to copy components. To copy a component, right-click on the component and then click on “copy”. Then click on the routine into which the component should be inserted, and click on “Experiment” and “Paste Component”.

The way to copy and paste routines and components across experiments is to open two Builder windows. Here is how to do this:

• Open the first experiment as usual.
• Then click on File → New to open a second Builder window.
• Then click on File → Open to open your other experiment in the second Builder window.

Please make sure to follow these exact steps!

Windows users

In the past, copying/pasting routines under Windows would not work if you opened the second experiment by double-clicking on the .psyexp file in the File Explorer. It was necessary to use File → New instead. As I do not have a Windows operating system, I am not sure if that is still the case.

34.4 PsychoPy demos

PsychoPy comes with a number of demos included. To see the demos, you need to click on “Demos” in the menu bar and then on “Unpack demos”. Next, you need to choose a location on your computer where the demos should be unpacked (this will create a new folder “PsychoPy3 Demos”). If you now click on “Demos” in the menu bar again, a list of demos will be displayed:

A useful demo is the “keyNameFinder” (in “Helper Tools”). It displays key names on the screen. If you would like to use a particular key in your input file, but you are not sure what its name is, run this demo.

The demo “spatialUnits” (also in “Helper Tools”) is helpful for understanding PsychoPy’s spatial units (height, norm, pix, etc.). This demo can be used in addition to our interactive app for visualising PsychoPy spatial units.

34.5 PsychoPy problems and errors

Appendix A includes a checklist for evaluating your experiment and covers frequently encountered PsychoPy error messages.

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1. You can draw simple geometrical shapes in PsychoPy using the Polygon component in the “Stimuli” components section.