It is possible on Prolific to set your study up to either allow multiple submissions, or to prevent this

Allowing participants to complete a study multiple times

Allowing multiple submissions can speed up data collection if it’s not important for you to receive responses from unique participants. This is particularly relevant for AI researchers who want to collect data in one study with varying tasks for a participant, but could be useful for researchers in many different scenarios.

How to set up multi-submission studies

When setting up your study on Prolific, you are able to choose to allow multiple submissions from each participant. Under the submissions section of the study setup page, select ‘multiple’ and the input the number of submissions allowed by each participant.

Participant experience

Participants access studies via their study dashboard. If you have set up to allow multiple submissions per study, the study will remain on the participants dashboard until A) they have reached the maximum number of allowed submissions per participant specified when the study was set up, B) there are no further places remaining on the study or C) they have indicated that they are not interested in completing the study.

Auto-approval threshold

As with every study on Prolific, you'll have the option to automatically approve submissions when they come in. Please note that for studies with multiple submissions enabled, any submission that takes less than half of the estimated completion time will not auto-approve. These submissions will need to be reviewed manually.

Preventing participants from completing a study multiple times

If it’s important to you to receive unique responses from individual participants, we’d recommend you set up your study to only allow one response per participant.

How to set up single-submission studies

When setting up your study on Prolific, ensure that you have selected ‘once’ in the submissions section. This will ensure that on Prolific each participant will only be able to submit the study once.

We aren’t able to prevent participants from visiting your external survey link more than once after they have opened it for the first time. Sometimes, participants revisit a survey link if, for example, they have missed the completion URL. It is important to distinguish between submissions on Prolific (which we guarantee are unique) and submissions to your survey software (which we don't have control over).

To prevent duplicate submissions in your external survey software, look out for a 'prevent multiple submissions' (or similar) option in your external survey software settings.

If you can see multiple submissions from a participant in your external study software when you have not set this up on Prolific, then we recommend that you simply delete the second submission from your data set. You'll be able to match the submissions using the participant's Prolific ID.

Participant experience

Participants access studies via their study dashboard. If you have set up to allow only one submission per participant, the study will disappear from the participant’s dashboard once they have taken it.

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