There are two ways to do this. Please note that it is currently not possible to block participants from studies that are being run at the same time. The methods below require submissions or studies to be completed prior to participants being prevented from accessing a future study.
Option 1: Use a custom blocklist
This can be particularly helpful for researchers running studies across multiple accounts. It is also useful for blocking participants when studies aren't completed yet and the 'previous studies' screener therefore cannot be applied.
- When creating a study, scroll down to the 'audience' section.
- Select 'prescreen participants' and then search for the 'custom blocklist' screener in the search bar. This screener can also be found in the 'custom screener' category.
- Enter the Prolific IDs of the participants you want to prevent from taking part in the study. Participants whose Prolific IDs you enter here won't be eligible to take part in the study.
- To generate the custom blocklist, you should ideally obtain the IDs from your Prolific data export or query string rather than using manually entered data. Prolific IDs manually recorded in your survey may contain errors, and invalid IDs will be rejected from the custom blocklist. See here for instructions on how to download your data export.
Option 2: Exclude participants from previous studies
To exclude all participants from selected previous studies from participating please follow these steps:
- When creating a study, scroll down to the 'audience' section.
- Select 'prescreen participants' and then search for the 'exclude participants from previous studies' screener in the search bar. This screener can also be found in the 'participation on Prolific' screener category.
- Select the names of the studies whose participants you wish to exclude from taking part in the new study.
- If newly completed studies do not appear on this list, you may need to refresh the page and they should appear.
Applying the 'exclude participants from previous studies' screener will exclude all participants from the selected studies (i.e. approved, rejected, returned, awaiting review and timed out participants).
Please note that the previous studies you want to block must be in the 'completed' section of your dashboard. These are studies that have finished and all participants' submissions have been reviewed and payment completed. If your previous study has not yet been completed but you would like to prevent participants who have participated in it from accessing a new study, please use the 'custom blocklist' option as outlined above.