URGENT: Slider working improperly online

URL of experiment:

Description of the problem:
Multiple participants have complained that the sliders, which worked fine last week, are behaving strangely today. My colleagues and I are unable to recreate the issue on our machines (mine is a Mac running Chrome). We need to fix this quickly to avoid contaminated data! Some example complaints:

  • “when i click them i click and the bubbles follow my mouse around instead of sticking”
  • “On the survey part, the selection cursor was acting weird. I think it changed my response on one of the Attention Check items.”
  • “So of the ‘bubble’ selections were a bit difficult If I moved the cursor across the screen it sometimes changed the responses and I had to go back and correct it.”

Update: it seems to be most common in Chrome on PCs. Maybe a recent Chrome update made this happen?
More than 10% of our workers have reported this issue, and I’m sure many more aren’t reporting it. Really hoping we won’t have to throw out these data!

@apitiot @dvbridges @jon - very grateful for any insight you might have!

@djangraw, thanks for the post. I noticed something similar and have already posted an issue on Github, which I will mark as urgent, with a link to this post.

Thank you @dvbridges! Here’s a video of the issue:

This is exceedingly weird indeed. I believe I have just managed to fix this.
Let me know if that suits!


Hey @apitiot, I am not sure whether the alignment issue is fixed. It seems to change depending on whether or not I refresh the browser - the example is the URL in the issue ( I am using Linux Chrome at the minute).

djangraw’s issue is fix, I believe, but yours, dvbridges, does not seem to be.
I’ll look into it first thing in the morning.


Thank you so much @apitiot! We were never able to reproduce the issue on our own machines, but we didn’t hear any complaints about this issue from today’s participants, so I think that suggests the fix worked! Thank you again for such a quick response.

I’m new here, so I might be way off, but i’m getting misaligned markers and bubbles for slider across browsers and platforms.

Hi everyone!
It seems I am having the same issue with slider. Some of my participants say that they cannot click on it (the white dot does not appear) and the labels are not visible. Any advise?

1 Like

Could you share your experiment with me so I can have a look?

Thanks a lot, here it is:

And this is the code:

Strangely enough, it is working on one machine, but not on the other (both are Windows 10 with the same google chrome versions)

We are unable to start data collection because the slider component is not working correctly. Can anyone please advise what to do in that situation?

I am unable to replicate the problem. Your experiment is working like a charm on all of the machines and browsers where I tested it. Can you get information about the device that people use to run it?

Hi everyone,
I think I have a similar issue. My slider is working properly when running on my local computer. However, when I run it online, it won´t show the labels and the marker. Does someone has an advice how to fix this? This is the code: https://gitlab.pavlovia.org/Ronja.M/gesichtswahrnehmung_3

Hello @Ronja,

I have just tested your experiment.
The reason why the marker is not appearing is that you are leaving the routine as soon as the rating is defined:

function GenderRoutineEachFrame(trials) { [...] if (Gender_response.getRating() !== undefined && Gender_response.status === PsychoJS.Status.STARTED) { continueRoutine = false; }

Consequently, there is no time for the marker to appear.
If you remove this line, or indeed replace it with an Enter key, then the marker appears:

As for the labels, I can see all of them on all operating systems and browsers on which I have tested your experiment. On which system/browser can you not see them, yourself?

But I wonder: is it the case that on your desktop version you can move the marker by pressing the mouse and not releasing it. Is that the behaviour that you are missing online?


Hi Alain,
thank you so much for your reply and thanks a lot for your advice with the marker! Replacing it with an Enter-Key just works fine (also I might just leave it with no marker, since it would be an additional key-press for the participants, which would extend our experiment quite a bit).

As for the labels, I just tested it on a different computer (Windows 10, with Internet Explorer) and it indeed just works fine. However, on my laptop it still just works as a desktop version but online I still dont see the labels:

I use Firefox on a Windows 10 system. I also tried Explorer and it doesn´t work either. Do you have any idea what causes this issue? If just my computer is being affected I definitely can live with it but am a bit worried, that it will occur also on other participants computers (as reported by Marinalosifian).

Thanks a lot!
Here is that information: Windows 10 Home (64-bit version) desktop pc, the problem still occurred after updating windows and the browser. The strange thing is that I only get the issue on Google Chrome, not on Firefox.

It seems that this issue cannot be fixed at the time, so we wont use the slider in our studies.