Logo Utrecht University

UiL OTS Labs


Recruiting adult participants

Last updated on 23 August 2019 by Iris Mulders

If you have suggestions on how to improve this document, or find mistakes, please send them to labman.gw@nulluu.nl

This howto details how to go about recruiting adult participants in the UiL OTS labs. If you would like to participate in an experiment yourself, as a participant, see our website for participants.


Recruiting subjects on-line: Who can use the UiL OTS adult participant database?

At UiL OTS labs, an ever-growing list of email addresses is available of people who have indicated that they want to receive invitations to participate in experiments at the institute. These participants regularly receive emails to sign up for experiments at the experiment homepage.

Use of this mailing list is restricted to UiL OTS experiments where participants are paid for participation. For issues surrounding participant payment, see this FAQ.

If you are an UiL OTS researcher, and you have secured money to pay the participants, and the type of participants you are looking for is available in the UiL OTS participant database, you can make use of our on-line subscription system.

How many and what kind of participants are in the database?

Most of the people on the participant mailing list are students or recent graduates of the Humanities faculty. These are mostly non-dyslexic native Dutch speakers (we do have some dyslexics on the list though).

About 80% of the list is female. If achieving a gender balance is important for your experiment, you will need to take special measures. (About 90% of the participants who sign up are female, and male participants are more likely to not show up).

There are over 1000 participants on the list. The email addresses and any personal details the participants provide are, of course, confidential information.

The number of participants that can be recruited through the mailing list depends on various factors, – if you have strict exclusion criteria it’s more difficult to find people who meet your criteria of course, and vacation or exam time make it more difficult too. But for most experiments, recruiting up to 100 unique (mostly female) participants is fairly easy.

If you are looking for ‘special’ participants, like elderly people, or people with another language than Dutch as their native language, the UiL OTS participant mailing list is not going to be useful for you; you will need to do your own recruitment. For special language groups, try Facebook, google groups, or specific hangouts (churches, expat organizations etc). For scheduling these participants, you could use http://www.slottr.com/, although it’s usually easier to convince people to participate through personal contact.

To find infants for testing, contact Desiree Capel.

How does on-line subscription work for the participant

The experiment homepage gives an overview of all experiments that participants can currently sign up for, as well as some general information. When participants are invited to sign up for a specific experiment, they receive a link to the subscription page for that experiment.

On the subscription form, the participant can pick a time slot and provide contact information and information required to determine whether they can participate in the experiment. The form always asks for name, phone number, email address, date of birth, native language, mono-/multilingual, sex, right/lefthanded, dyslexic/not dyslexic, and social role (student/working/retired/other).

The participant will get an automatic confirmation over email. In this email, they also receive a link where they can unsubscribe from the experiment as long as the time slot they subscribed for is still in the future; by filling out their email address and date of birth, they get an overview of the time slots that they have subscribed for. If they unsubscribe from your experiment, you will receive a notification over email.

What kind of information do you need to supply to make use of the on-line subscription forms

Provide this information about a week in advance, so that the timing of the invitations to participants can be coordinated with other experiments. Hashing out the details of your form (criteria) may take a few back-and-forths, too. The actual invitations to the participants will only be sent when you are 100% ready to run (see below), but this should not stop you from requesting the subscription form well in time.

Experiment details

FEtC-H approval

Your experiment needs to be approved by the FEtC-H (Faculty Ethics assessment Committee โ€“ Humanities) before participants can be recruited. For more information, see the FEtC-H website.

Experiment details

This is the name that will be shown on the website. The more memorable, the better; the purpose is to give the participants something they can remember by whether theyโ€™ve already participated or not. Some image from a filler or practice item usually works well. Examples from past experiments: 'Sailors with painful necks', 'The doctor has pineapple'.
The standard amount is 10 euros per hour, usually with a minimum of 5 euros for experiments shorter than 30 minutes. See this howto.
Participants like to know what they can expect; please fill this field out in Dutch if you can!
Be exact!
Please give a full list; if you are filling out this form but are not the contact for the participants (see below), please indicate so here.


One of the experimenters has to be the contact person for this experiment. This person's phone number and e-mail address will be provided in the confirmation message to the participants when they subscribe.
The phone number of the lab you will be testing in will also be added.

Participant criteria

What are the criteria the participant should meet in order to be able to participate in the experiment?
The standard criteria are listed below; the most usual option is selected by default. Change this selection if you want to divert from it.
At the bottom a text area is provided where you can list any other criteria.

NB: some (not many) of the Dutch participants on the list are early dialect speakers (from Limburg etc). They will be in the database as native Dutch speakers; if you want to exclude them and test only speakers of standard Dutch (whatever that may be), indicate so below in 'other criteria'.
Note: to avoid consent issues with underage participants, it's a good idea to recruit only participants that are at least 18 years old.
For example, you may want to exclude participants who participated before in a certain other experiment (please indicate name of the experiment and in which month and year it was run, if you can). Or you may have other criteria. Please fill this field out in Dutch if you can, and be very specific about the criteria - vague criteria confuse participants.
If you indicate that you want to run, for instance, 3 participants at the same time, every timeslot you add to the form will actually make 3 timeslots for that one time, distinguished by 'werkplek 1', 'werkplek 2', and 'werkplek 3'.

How does it work for the experiment leader

Once your experiment subscription form has been created, you will receive an answer with your username and password for the experiment leader section of the subscription system; you can then put the time slots on your subscription form yourself.

After logging in, you will see an overview of your experiments:

Example overview of experiments (screenshot, click to enlarge)

Use of the system is self-explanatory for the most part; do read the information below for pointers on the most effective and constructive way to use it.

Adding a photo of yourself

You can edit your details through the ‘edit profile’ link. If you want, you can also upload a photo of yourself. The photo will be shown on the subscription form for your experiments, and may increase participant awareness that you are a real person ๐Ÿ˜‰

Adding timeslots

Clicking on the clock icon clock will take you to a page where you can add timeslots to your experiment:

Adding timeslots, example (screenshot, click to enlarge)

Pro tip: after you’ve added a time slot, use the back button in your browser to add the next one (this will take you back to the previous time slot, which saves you the trouble of filling out date, year and time from scratch).

To remove a timeslot, click on the garbage can bin_closed following it.

Don’t forget to also reserve lab space in the reservation system for the times you want to run participants!

For most experiments, your time slots will be fully booked within a day or so, provided the invitation is sent out a few days before you start running. Do make sure to add about 10-15% more time slots than you need participants, to compensate for no-show participants. Send your participants a reminder the day before their appointment (see below), otherwise you can easily get 25% or more no-showers.

Opening your experiment for subscriptions

Once you have added the timeslots:

  1. Make sure that you have piloted your experiment on yourself and that it is 100% ready to run, technically. Check your data to make sure the output is what you need for your analysis!!
  2. Make sure that you have piloted your experiment on some others, and again, check your data and analyze it to make sure you have everything you need!! (NB: To pilot your experiment, you are expected to find your own pilot participants. If this is difficult for you, contact Iris Mulders to discuss the best solution. Also, if your pilot participants are likely to be on the mailing list, let them sign up on your subscription form to prevent them from signing up once you start running for real (or from signing up for a follow-up experiment). Contact Iris Mulders to discuss).
  3. Verify that the time it took your pilot participants to complete the experiment is what you said for the subscription form (if not, this – and anything else – can still be changed)
  4. Make sure that you have arranged for money to pay the participants, and have printed a sign-off list
  5. Make sure that you have approval of the FEtC-H and your consent forms are printed, ready for the participants to sign
  6. Make sure that you have made any other arrangements you need to make to run your experiment

If you are 100% ready to run participants, you can click the experiment closure icon delete to open your experiment for subscriptions; the icon will change to a green check mark accept. Your experiment will now appear in the list of available experiments on the Experiment homepage for participants.

Send an email to Iris Mulders to indicate that you are ready for the invitation to the mailing list to be sent out. Ideally, the invitation is sent out two days before you start running, but if necessary the day before can work pretty well, too. Note that invitations are not sent out on Fridays or Saturdays (participant response is approximately zero on those days).

Viewing participant info and sending reminder emails

Click on the participants icon participants to see an overview of your timeslots with the participants who have subscribed to it. You will receive an email when a participant unsubscribes, but not when a participant subscribes. The participant overview is how you track how many participants are subscribed.

In this view, you can sort the fields by clicking on the name of the field; you can also limit the view to only certain participants by typing in a search box at the bottom. For instance, if you type 2017-10-07 in the ‘date’ field, you will only see the participants scheduled for October 7, 2017.

This is convenient for sending reminder emails; limit your view to only the participants who are scheduled for tomorrow, then check the boxes in the ‘reminder’ field for the participants you want to send a reminder email; click ‘send’ to send the reminders. The participant will receive an email noting the time, date and place you are expecting them, and your contact info so they can contact you personally in case they need to cancel with less than 24 hours notice.

Bear in mind that the participant’s information is confidential. Do not use email addresses for your own purposes. Do not share emails or any other participant details with other people (not even your close colleagues!). Do not leave a page with the details open on a public computer, for instance a lab computer. Do not leave printouts lying around.

How to deal with no-show participants:

  1. Call or email them to let them know that you’ve been waiting for them (sometimes they don’t realize there’s an actual person waiting for them)
  2. Add a comment to the participant so I can take them off the list if they make a habit out of not showing up. Click on the talk balloon comment in the field ‘Actions’ for the participant in question and add a comment. You can add other types of comments there, too (to indicate lack of effort for instance, or resistance to instruction).
  3. After you have emailed/phoned and added the comment, click on the participant icon with a red strikethrough unsubscribe; this will unsubscribe the participant from your experiment, and sends them an automated email that tells them you unsubscribed them. There are two good reasons to do so:
    1. it opens up the possibility for the participant to subscribe for a different time slot (they can only be subscribed for one time slot per experiment)
    2. it keeps your overview up-to-date; this is particularly handy if you will want to exclude the participants in this experiment from participating in a later experiment

If a participant unsubscribes through the system less than 24 hours before you were expecting them, a comment will be added automatically for them.

Tips, tricks and factoids

  • New feature (November 2017): the system now sends out personalized links in the invitations, which fill out the participant details in the subscription form when they click the link. This makes it easier for participants to sign up. Unfortunately it also means that if participants forward their invitation email to an acquaintance (ignoring the instruction to not do that), the acquaintance may sign up using the first participant’s details (of course that can only happen if they don’t read, but – people don’t read). You can check by comparing the participant’s birth date as it appears in the system, with the birth date they fill out on their consent form. If you discover a discrepancy, let Iris know.
  • Click on the excel icon in the top right corner to save your participants to an excel sheet. Treat this excel sheet as confidential information. Delete any participant info from it that you don’t really need.
  • When you have finished running your experiment, close the experiment for subscriptions.
  • Privacy feature: some time after your experiment has finished running, the participant’s contact details will be set to be invisible for you. If you need to see the contact details, for instance to invite them to a follow-up experiment, contact Iris Mulders. You will be asked to not contact participants who have unsubscribed from the mailing list in the mean time, or at least be extra careful and apologetic if you do need to contact them.

Up to contents

If you find mistakes in this page or have things to add, please send them to Iris Mulders.