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Best Practices for Designing and Implementing Pack&Go Studies

Below is a list of general tips and recommendations for Pack&Go experiments.

  • Pack&Go does not currently support studies on mobile or tablet; make sure your participants are using a desktop browser during testing.

  • Your main experiment file should be a script, not a function. If you don’t want to modify any code, your experiment file can always be a simple one-line script that executes the experiment function. For example, below is a valid experiment file:

  • Your pathing must be relative, not absolute. Below are examples of absolute and relative pathing, for a study whose main script is located in C:\Users\john\Documents\MyStudy


Absolute path (DO NOT USE)

Relative path (USE)

Same folder as experiment script



Subfolder called images



  • Avoid changing the working directory during the course of the experiment.

  • We recommend letting the experiment run for 10-15 second before collecting time-sensitive data, to allow the network time to stabilize.

  • TEST EVERYTHING. We do not reimburse credits for studies where coding errors or a failure to test results in data/session loss.

  • Instruct participants to avoid having other tabs or browsers open during the test session, especially if these other browsers include streamed data (e.g., Spotify, Youtube, downloads in progress)

  • Similarly, participants should not be streaming/downloading content during testing (e.g., torrenting) as this can affect network performance.

  • We recommend that you time normalize your experiment, as it may run at a different framerate than on your computer.

  • We also recommend using normalized spatial units (the default in PsychoPy) as the participants may have different monitor resolutions/sizes.

  • If you are hoping to control for stimulus size, there are different ways to achieve this depending on your requirements for simplicity and tolerance for variability. See Brascamp (2021; and Yung et al. (2015; ) for examples.

  • Pack&Go does not, by default, save any identifying participant data. Consider using anonymous ID codes in your studies, and collect only the minimum amount of personal details you need to conduct your research.

  • Consider including attention checks or catch trials in your study, to ensure your participants are not distracted/multitasking.

  • Consider saving intermediate data files often, in case subjects surpass the set time limit.

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