Experiment gets stuck in the middle of the run

Description of the problem:
We are running an experiment using a link generated by Pavlovia. In half of the times running the experiment it gets stuck in the middle with a black screen and there is no way to proceed. It happens when participants are asked to press Shift to continue but the key presses do not assist and the experiment is completely stuck.

The experiment presents many images (160 of them before it gets stuck) and all the images are downloaded to the participant’s computer before the experiment actually begins (so they are all in memory when it begins). The presentation of the images goes smoothly till it gets stuck.

Before running the experiment we made sure to close Chrome and start the computer anew before each participant but that did not seem to have an effect, and also this happened on several computers.

We would appreciate any help understanding what could cause this and how to solve this issue.

Please let us know if more information is needed

Thank you.


You can find some information about online debugging at Debugging online - Thomas's demos.

Is this the only time people need to use the Shift key? Shift works in combination with other keys or mouse clicks. What happens if you use a different key?

Best wishes Jens