Can I exclude participants who have previously participated in my study?
Yes, that's no problem. To exclude participants 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. 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.