Randomly selecting stimuli while keeping count

Online experiments
1

Hello,

I have a question about randomly pooling from a set of stimuli, while controlling for what has been shown before. Is that possible to do?

To clarify, I have a task with a set of 1000 stimuli. Each time an online participant decides to do the task, I want stimuli to be drawn and shown randomly to the participant, for as long as they want to continue doing the task, without replacement.

Furthermore, I want to make sure that if for a single stimuli I get 30 responses across different subjects for example, the program stops selecting to show that stimuli at random to participants.

I have no idea how to do this online, since I can’t read and write a datafile from a local directory as I would with an offline task. Is it possible to do so some other way? Thank you so much in advance for your help.

2

My VESPR Study Portal is designed to allow balanced allocation to groups but to use it for this you’d need to decide which stimuli would be shown to each group, which wouldn’t be ideal.

How many of the 1000 stimuli does each participant see? In theory I think I could add this functionality to the portal so long as PsychoPy could receive a long delimited string as an expInfo variable. Based on my current functionality, it would allocate a random selection of the currently least selected stimuli. Interested?