When you run a study on Prolific using an external survey tool, Prolific automatically adds three unique IDs to the link sent to each participant. These IDs help you identify participants, link their survey responses to their Prolific demographic data, and manage submissions.
In this article, we'll explain what each ID is, why you need to collect them, how to set this up for your study, and what to do if you haven't collected them.
What are Prolific IDs?
There are three IDs associated with a participant's connection to your external survey tool:
Prolific PID: Uniquely identifies a Prolific participant.
Session ID: Identifies the submission associated with the participant's connection to your survey tool.
Study ID: Identifies the Prolific study associated with the submission.
Together, these IDs help you connect the data collected in your external survey tool with the corresponding participant and study on Prolific.
If you're using the Prolific API, you can also use these IDs to help authorize access to your external survey. By calling the GET submission endpoint and validating the participant and study IDs returned, you can check that a participant is associated with the expected submission and study.
Why do I need to record Prolific IDs?
Recording Prolific IDs allows you to link your survey responses to the correct participants on Prolific.
Without these IDs, you won't be able to:
Match participants' survey responses to their Prolific profiles.
Access the demographic information associated with those participants.
Identify and reject poor-quality submissions when appropriate.
We recommend recording Prolific IDs for every study that uses an external survey tool. This helps ensure you can connect your data to the correct participants and manage submissions effectively.
How do I record Prolific IDs?
When setting up your study, you'll be asked how you want to record participant IDs. You have three options.
Option 1: URL parameters (recommended)
Prolific automatically appends all three IDs to the URL sent to participants when they enter your external survey.
You'll need to configure your survey tool to capture these URL parameters and store them alongside each participant's responses.
Each survey tool works differently, so follow the relevant integration guide for step-by-step instructions on setting this up.
Option 2: Ask a question in your survey
You can ask participants to enter their Prolific ID directly into your survey. For example:
"What is your Prolific participant ID?"
You can then use their answers to link survey responses to Prolific participants.
Important: This method relies on participants entering their IDs correctly. Participants may make honest mistakes or deliberately enter an incorrect ID, which can result in responses being linked to the wrong person.
Only use this method if having a 100% accurate link between participants and their responses isn't essential for your study.
Option 3: I don't need to record these
You can choose not to collect Prolific IDs if you don't need to link survey responses to Prolific participants.
However, this means you won't be able to link survey responses to Prolific profiles, access the corresponding demographic data, or reject poor-quality submissions based on the survey responses.
Important: You can't reverse this decision once your study has been published.
If you need to start recording IDs after publishing your study, you'll need to:
Stop your existing study.
Duplicate the study.
Update the participant ID recording setting in the duplicated study.
Publish the duplicated study.
How do I secure my URL parameters?
If you want additional assurance that the URL parameters sent from Prolific to your external survey tool haven't been tampered with, you can enable Secure external URL when creating your study.
When this feature is enabled, Prolific securely signs the URL parameters before redirecting participants to your survey tool. The URL includes a JSON Web Token (JWT) containing the secured parameters.
Your survey tool must verify the JWT before authorizing a participant to take the study.
This provides two key assurances:
Protection against tampering: The secured parameters help verify that the Prolific IDs are accurate and haven't been altered.
Time-limited access: The token expires after two minutes, helping prevent participants from reusing the URL after their initial eligibility check.
For implementation details, including how to verify the JWT and use the new property on the create-draft-study endpoint, see our API integration documentation.
Note: Secure external URL is currently available only to certain workspaces. If you'd like access, please register your interest here, and we'll contact you when the feature becomes available in your workspace.
I didn't collect Prolific IDs. What can I do?
If you've completed your study without collecting Prolific IDs, we're unfortunately unable to provide them after the fact.
Prolific doesn't store participants' survey responses. If an ID wasn't captured by your survey tool during the study, it generally can't be recovered through Prolific.
Can I recover IDs from Qualtrics?
If you ran your study using Qualtrics, you may be able to recover Prolific IDs by updating your survey settings and exporting your data again.
To try this:
Open your survey in Qualtrics.
Go to Survey flow.
Add or update an embedded data field named
PROLIFIC_PID.Save your changes.
Re-export your survey data.
The IDs may appear in your newly exported data, but this isn't guaranteed. If they don't populate after you've followed these steps, they can't be recovered using this method.
Frequently asked questions
Which ID should I use to identify a participant?
Use the Prolific PID to uniquely identify a participant. The Session ID identifies the submission associated with their connection to your survey tool, while the Study ID identifies the study associated with that submission.
Can I collect Prolific IDs after my study has started?
If you selected URL parameters or asking a survey question when setting up your study, make sure your survey tool is configured to capture the IDs correctly. If you selected not to record IDs, you'll need to stop your study, duplicate it, change the setting, and publish the duplicate.
Can Prolific recover IDs that my survey tool didn't record?
No. Prolific doesn't store participants' survey responses, so IDs that weren't captured during your study can't be provided by Prolific. If you used Qualtrics, you can try the recovery steps above, although success isn't guaranteed.
Do I need to secure my URL parameters?
Secure external URL provides additional protection against tampering and limits how long the token can be reused. If the feature is available in your workspace and you need these additional assurances, you can enable it when creating your study.
Need more help?
For guidance on configuring your survey tool to capture Prolific IDs, see our integration guides. If you're using the API, refer to our API integration documentation for details on validating submissions and verifying secured URL parameters.