If you want to prevent certain participants from taking part in your study, you can do this in two ways:
Exclude participants from other studies - useful when you want to exclude everyone who participated in one or more of your previous studies.
Use a custom blocklist - useful when you want to exclude specific participants by their Prolific IDs, particularly when running studies across multiple accounts.
Option 1: Exclude participants from other studies
You can exclude all participants who took part in selected previous studies from participating in your new study.
How to exclude participants from previous studies
When creating your study, scroll down to Recruit participants.
Select Add filters
Search for exclude participants from other studies.
Select the screener. You can also find it under the Participation on Prolific screener category.
Select the studies whose participants you want to exclude from your new study.
Note: Only studies in your current workspace will be available to select.
Who will be excluded?
Applying the exclude participants from other studies screener will exclude all participants who took part in the selected studies, regardless of their participation status. This includes participants whose submissions were:
Approved
Rejected
Returned
Awaiting review
Timed out
Important
Only participants who completed your previous study before you published the new study will be excluded.
Participants who complete the previous study after you publish the new study may still be eligible to see and take part in the new study.
Option 2: Use a custom blocklist
A custom blocklist lets you specify individual participants that you don't want to be eligible for your study.
This can be particularly useful if you're running studies across multiple accounts, or if you only want to exclude a specific group of participants rather than everyone from a previous study.
How to create a custom blocklist
When creating your study, scroll down to Recruit participants.
Select Add filters
Search for Custom Blocklist.
Select the screener. You can also find it under the Custom Screener category.
Enter the Prolific IDs of the participants you want to prevent from taking part in the study.
Any participant whose Prolific ID is included in the blocklist will not be eligible to take part in the study.
How to get participant IDs
Where possible, we recommend generating your custom blocklist using participant IDs from your Prolific data export or query string, rather than entering IDs manually.
Participant IDs recorded manually in your survey may contain errors, and any invalid IDs will be rejected from the custom blocklist.
See our guide on how to download your data export for instructions.