PsychoJS - Maximum number of simultaneous studies?

Hello there.
For my current study, I need to create personalized online surveys for each participant. These surveys are simple 2AFC tests, with the participant having to choose between two familiar pictures at a time based on personal preference, and also answer a pair of questions regarding their feelings towards the picture chosen. Given that the pictures have to be personalized (i.e. each participant has a different set of 12 pictures), I have found no other way to implement this other than creating individual surveys for each participant. I suppose I could create some sort of account system or something, but that goes way beyond my skills.
Thus, my question is, is there a limit on how many studies a single account can have active at the same time using PsychoJS? I will probably need around 200, and while I haven’t found any answer in the documentation, something tells me that this number alone will make it a bit difficult.

In any case, I would appreciate any help with this matter.

I don’t know of a maximum. However, you should definitely rethink your approach here.

You can create a single experiment where the relevant images are downloaded based on the participant id.

You can see same sample code here (under Download Resources):

Thank you for your help!
That sounds reasonable. However, wouldn’t that allow other people to access the images if they manage to get their hands on the user ID? Either that, or the ID would have to be rather complicated.

I don’t know, I’m just worried about privacy issues, given to how important it is.

With your method were you planning to name the experiments in an arbitrary way such that people when knew one link couldn’t guess another?

You could have the participant “number” being the participant’s email address. Then someone would need to know another participant’s email address to pretend to be them.

You’re right; my plan was to create arbitrary access links for each study, such as they could not be figured out. The thing is, a single participant has to access the study several times (around 10, preferably more) in the span of two-three weeks. My idea was to have a single link for a single participant, such as the participant would only need to access the link from a saved email (or something like that). I fear that (based on past experience of how difficult some participants can be), adding a “please insert your ID” field or the like would hamper the data collection process.

I can see how elegant your solution is, though, and may as well just go with that. I think that asking the participants to type their own email should not be that demanding. I hope.


You don’t need to ask them to add their own email address. Anything in the expInfo dialogue box can be prefilled using URL variables. You could therefore use arbitrary codes, such as,

Now that is a revelation! Game-changer! I did not know you could do that!

To be fair, I’m fairly new to PsychoPy, so I guess there’s still much to learn.

Anyways, thanks a lot. I think I can clearly see a better approach now.

That’s the basis of my counterbalancing apps. It’s extremely useful for online studies.