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Prolific IDs randomly lost

URL of experiment:

Description of the problem:
Yesterday I had five participants from Prolific complete my experiment on Pavlovia. The output data from Pavlovia failed to capture the Prolific IDs from two of them. Instead, the default value for the prolificID property in the expInfo object was saved. I’m using the query string method to capture Prolific IDs in the URL. Does anyone know why this method would fail at random? I’m using wakecarter’s page to assign participant IDs. Has anyone had problems with wakecarter’s page for passing prolific IDs to pavlovia?

Can Prolific IDs contain punctuation?

Please could you message me the URL your using in Prolific to my site so I can have a think about what might cause it to fail.

1 Like

Prolific IDs have 24 alphanumeric characters. I do not think they contain punctuation.

I really appreciate your help! I am considering a backup method by prompting participants to manually enter their IDs if the prolificID was not successfully transferred. But that won’t be foolproof.

I can see that you didn’t test it.

If you use a URL of the form https://moryscarter.com/vespr/pavlovia.php?experiment=b/html/&folder=a&prolificID={{%PROLIFIC_PID%}}&studyID={{%STUDY_ID%}}&sessionID={{%SESSION_ID%}}
the participant will be sent to:
https://run.pavlovia.org/a/b/html/?participant=1&id=&session=&researcher=

The reason for this is because only variables that I have specifically added to my app are passed through (id, session and researcher)

If you use a URL of the form https://moryscarter.com/vespr/pavlovia.php?experiment=b/html/&folder=a&id={{%PROLIFIC_PID%}}&researcher={{%STUDY_ID%}}&session={{%SESSION_ID%}}

then the participant will be sent to https://run.pavlovia.org/a/b/html/?participant=2&id={{%PROLIFIC_PID%}}&session={{%SESSION_ID%}}&researcher={{%STUDY_ID%}}

You can then use those three variables in Pavlovia to construct the correct return URL.

You’re right, I could not find a way to launch the study from the participant’s perspective from within Prolific. I have verified that the participants whose IDs did come through actually copied and pasted their IDs on the loading screen. Because I was using a variable name not supported by your page to transfer the prolific ID, the loading screen displayed a field that was called “prolificID” on account of not being initialized by the URL. The participants whose prolific IDs did not “come through” failed to copy and paste their IDs because there was not clear instruction to do so.

I’ve also verified that the solution you suggested automatically transfers the prolific ID by asking a participant if they had to manually enter their ID or not. She said she didn’t have to manually enter it but I received it through Pavlovia.

Thanks a lot!