Yes. There are a few ways to do this.
Using a custom blacklist
Simply go to step 3 "Prescreening" and select "Custom blacklist". Participants that you enter here won't be able to take part in the study.
If you have good reasons to believe that a participant is purposefully submitting low quality responses, cheating, spamming, or engaging in any other unacceptable behavior, please report this back to us by briefly describing the issue and sending the relevant Prolific IDs. We will make sure to block accounts like these.
Blocking a previous study
To exclude participants from a previous study from participating again, all you have to do is go to your Dashboard and to the Prescreening tab, scroll down to "Previous Studies" and select the study whose participants cannot participate again in the new study. Just move the old study from the left box to the right box.
The previous studies you want to block must be in the "Completed" section of your dashboard. These studies are have been stopped and have all participants reviewed.
If you have multiple old studies, you can move all of them to right box at once. Now click on "Apply previous studies requirement to study" and you're done.
Please note that Previous Studies will also exclude participants who have made Returned submissions in your previous study.