Alternating between 2 conditions for even distribution

Hi all,

I am very new to PsychoPy and am currently using the builder to create a random dot motion task. Everything is ready to go and the task is running successfully, however I would like to adjust the code to alternate the 2 conditions that present a message prompt before stimulus onset (Condition one: speed prompt, accuracy prompt, speed prompt, accuracy prompt; Condition two: accuracy prompt, speed prompt, accuracy prompt, speed prompt) between participants so that participant 1 will receive the prompts SASA and participant 2 will receive ASAS and so on and so forth. At the minute I have found code from this forum that allows one of these condition files to be chosen randomly, however, this does not allow for an equal distribution between conditions between participants. My supervisor has suggested all even number participants receive the SASA condition and all odd number participants receive the ASAS condition and I was wondering how to go about this as I am not at all familiar with the coder. The end goal is to have a 50/50 split between conditions in the data.

The flow can be found in my comments below as I am a new poster so was unable to post more than two screenshots!

The code that selects one file randomly:

The excel files of the two different orders: SASA and ASAS

Online or locally?

Online you can use one of my VESPR tools or the Pavlovia shelf.

Locally the easiest option is for the researcher to select in the expInfo dialogue box.


This is my current flow so I’m not sure where to go from here

In your loop put expInfo['group'] + '.xlsx'

In your dialogue box (experiment settings) add: group with options ['ASAS','SASA']

great thank you!