In most cases, you should use Prolific's prescreening tools to filter participants before they enter your study. This ensures everyone who takes part can complete it and receive their reward. Find out how in our How do I use Prolific's demographic prescreening? article.
There are several situations in which screening participants in a study is allowed. This article explains what those are and how to handle them correctly.
What if the prescreener I need doesn't exist?
If you need to recruit a niche demographic that our existing filters don't cover, you can use custom screening instead. Find out how in our custom screening guide.
How do I validate my prescreeners?
Setting up prescreener validation involves two steps: configuring your completion paths in Prolific first, then building the validation questions into your external study.
Step 1: Set up your completion paths in Prolific
A completion path tells Prolific what to do with a participant's submission when they reach a specific end-of-survey page. If you're validating prescreeners, you need at least one completion path that handles ineligible participants, so you can identify them in your dataset and automatically request that they return their submission.
Important: Set your completion paths up before publishing your study. Once your study is live, any changes to completion paths can disrupt submissions that are already in progress.
How to set up your completion paths
Go to the "Data collection" section of your study setup page
Scroll down to "Completion paths"
Click "Add a completion path"
Select "Custom" from the list of labels and give it a clear name, for example, "Ineligible for study." This label is visible to participants, so make sure it clearly explains why they weren't eligible
Click "Add path"
You'll see three options for processing submissions. For this scenario, select "Request a return"
Note: the message sent to participants will match the label name you chose in step 4
Copy the redirect URL and completion code. You'll need these when building your study
Step 2: Add the validation question to your survey
In your external survey tool (for example, Qualtrics or SurveyMonkey), add a validation question at the very start of your survey. This must use the exact wording as it appears on Prolific, which you'll find when you add a prescreener to your study setup. See our Integration Guides for detailed guidance for your platform of choice.
Then, configure your survey so that any participant whose answer doesn't match their prescreening response is redirected to the end-of-survey page using the completion path URL you copied in Step 1.
Note: Don't ask for a participant's date of birth when validating age, as this is personally identifiable information and is not permitted on Prolific. Instead, ask: "What is your current age in years?"
What if a participant's answer doesn't match their prescreening response?
Keep in mind that mismatches aren't always intentional. A participant's circumstances may have changed since they completed their About You profile.
When a participant's answer doesn't match their prescreening response, they'll be redirected to the completion path you set up in Step 1.
If 'request a return' was selected in your completion path, the participant will automatically receive a message asking them to return their submission.
If the participant hasn't returned the submission within 7 days, you can use our in-app messaging tool to prompt them to do so. If the participant hasn't returned their submission, please contact Support at least 2 working days before the auto-approval deadline of 21 days. You can contact Support using the blue icon in the bottom right-hand corner of your screen.
You must not reject a participant solely because their study responses don't align with their prescreening data. Read more about when to reject, return and approve in our approving, rejecting, and returning submissions guide.
Can I validate my study's device compatibility and technology use requirements?
Yes, as long as you've clearly stated your device and technology requirements before participants enter your study. You must:
State device and technology requirements clearly in your study description
Specify requirements in the "Study details" section of your study setup
Run the validation check at the very start of your study, before participants invest significant time
Note: Prolific does not include the specific devices participants used to access your study in the demographic data download. The device requirements you set are there to inform participants what device types are compatible with your study, but we don't track or store which devices participants actually use when taking part.
How do I validate device compatibility and technology requirements?
Prolific doesn't automatically restrict participants by device type. However, there are two ways to handle this: using your survey software's built-in device detection, or asking participants directly which device they're using.
Before you do either, you need to set up a completion path in Prolific to handle participants using incompatible devices.
Step 1: Set up your completion path in Prolific
Go to the "Data collection" section of your study setup page
Scroll down to "Completion paths"
Click "Add a completion path"
Select "Incompatible device" from the list of labels
Click "Add path"
Choose how you want to process the submission. For this scenario, select "Request a return"
Copy the redirect URL and completion code (you'll need these when building your study)
Step 2: Validate the device in your survey
Some survey tools support built-in device detection. For example:
For step-by-step instructions on setting this up in your survey tool, see our integration guides.
What if my survey software doesn't support device detection?
If your survey software doesn't support device detection, ask participants directly at the start of your survey what device they're using, and use branching logic to redirect anyone on an incompatible device to the completion path URL you copied in Step 1.
Some survey software also supports technology tests, for example, audio output tests that can detect whether a participant is using headphones.
Ensure device validation occurs at the very start of your study, before participants invest significant time. Here's an example end-of-survey message you can use for incompatible devices:
"Thank you for your interest in this study. However, this task must be completed on a laptop or desktop computer, and our data indicates you're using a mobile device. Please return your submission on Prolific by clicking the 'stop without completing' button."
We also recommend running a pilot study before launching to your full sample to make sure your validation is working as expected.
How do I screen based on attention and comprehension checks?
You can screen out participants who fail two valid attention checks. Before you do, review our Attention and Comprehension Check Policy to make sure your checks meet Prolific's standards. If they don't, we may ask you to approve those submissions regardless.
To set this up:
Go to the "Data collection" section of your study setup
Add a custom completion code path and select "Failed attention checks" from the dropdown
You'll see that a custom redirect URL and a completion code are generated
Configure your external study to direct participants who have failed your attention checks to an end-of-study page, with the redirect URL provided.
When the participant is redirected back to Prolific, the completion code is automatically entered, and you'll be able to see exactly who failed your checks.
Comprehension checks
If a participant fails a comprehension check twice, then they should be immediately asked to return their submission by closing the study and clicking 'Stop Without Completing' on Prolific.
Please read our Attention and Comprehension Check Policy for more information, such as what constitutes a fair comprehension check on Prolific.
How do I filter out participants who don't consent?
If a participant doesn't consent to take part in your study, you need to redirect them to a completion path. Set this up before you publish your study.
How to set up your completion path
Go to the "Data collection" section of your study setup page
Scroll down to "Completion paths"
Click "Add a completion path"
Select "No consent" from the list of labels
Click "Add path"
For this scenario, select "Request a return"
Copy the redirect URL and completion code (you'll need these when building your study)
Then configure your survey to redirect any participant who doesn't consent to the completion path URL you copied above. This frees up their spot for a new participant.
Note: You must not reject a participant if they haven't consented to your study. Read more about when to reject, return and approve in our approving, rejecting, and returning submissions guide.
What happens to submissions that are not reviewed?
If you've selected "Screened out" as your completion path label
This automatically enables custom screening. Screened-out participants are paid the fixed reward you set during study creation, and their submissions won't count toward your overall submission spaces. If a participant enters the wrong completion code, their submission will appear in your "Awaiting review" tab and will need to be manually approved, rejected, or screened out. If you don't review these within 21 days, they'll be automatically approved and paid at the screen-out reward amount.
If you've used any other custom completion path (for example, "Incompatible device" or "No consent")
If you don't manually approve or reject these submissions within 21 days, they'll be automatically approved and paid the full study reward amount. If you requested the submission to be returned and the participant hasn't returned it, please reach out to our support team as soon as possible.