Polygon Opacitiy in Online Experiment

URL of experiment: https://run.pavlovia.org/AkaiRed/self-prioritization

Description of the problem:

Hi, I’m trying to make a simple visual perception task using pavlovia.
The goal is simple. I want one of circle, triangle, or square to be presented in each trial.
It wasn’t hard to implement the design using opacity variable and condition.xlsx file.

But the things didn’t work out under the online environment.
Three polygons show up at the same time, which means opacity manipulation is not working.
The other trial-by-trial variable works fine, so I think the problem is with the opacity updating of PsychoJS.

Tried it in other ways, such as adding extra variable in the condition file for each shape or using JS code directly to set the opacity, but none of them worked.
It is quite simple and concrete design, I don’t see what is the problem.

Would be great if anyone can help me.

If the task you give above shows the problem reproducibly, than I suggest you post this as an issue at:

But as a short-term workaround, you could try indirectly controlling the visibility of the unwanted polygons by giving them a position that is off-screen.

Hi Michael, thank you for your reply.

I’ll first try your solution for immediate problem,
and then work on opacitiy issue in my free time.
If the problem becomes more evident, I will submit an issue.


Hi AkaiRed, did you manage to do it? Do you mind sharing the solution?

Hi. At the time I posted, I couldn’t fix the issue so used the quick solution by Michael.
I tried to replicate the simple version of a problem now, and it works perfectly fine.

I guess a recent version of psychopy has fixed the issue I had,
so I recommend you to update your psychopy to latest release and try again.

Comment me if the problem continues. I look up for an another solution :slight_smile: