Study Types


Xlab offers flexibility and customization of services to lower the barriers to entry for scholars.

Full service experiments include Xlab staff handling recruitment, check in, and payment. Recruitment includes creating the study and opening timeslots in the Sona system where participants can sign up. On the day of the experiment, Xlab staff will check in the participants and assign their seats. Immediately after the experiment, Xlab staff will pay the participants. Payment can be a flat rate or variable amounts.

Self service experiments allow you to conduct aspects of the study on your own while utilizing the excellent facilities of Xlab. For example, a researcher may bring their own participants and choose to pay their participants by cash themselves. Researchers interested in self-service must have approval in the study CPHS to view the participants' names and information.

In-lab Study

In-lab studies take place at Xlab, Hearst Gymnasium, Suite 2. The main room of Xlab has 20 laptops and Room C has 16 laptops. Both rooms can be run simultaneously if two Research Assistants are present, for a maximum of 36 participants during each session. There are also three rooms in the back available for small group studies that can hold maximum 2-4 participants per session.

Subject Recruitment

Xlab's participant pool of over 5,000 UC Berkeley students, staff, and alumni can be filtered based on age, sex, race, English proficiency (Native English speaker), and expected year of graduation. Subjects in the pool will be recruited for experiments by email and social media advertisements on Facebook and Twitter. People already in the subject pool can be solicited for specific experiments through email. Some experiments have special subject selection requirements (pairs, multiples, demographic balance, etc.). The request must be included in the Experiments Schedule Form.
Over-recruitment and show-up: Subject participation show-up rate for studies is approximately 70-80%. Therefore, to meet the maximum number of subjects requested for a study session, Xlab staff can over-recruit participants based on our experience and trends in academic calendar. If Xlab over-recruits and the maximum number of subjects come to the lab as scheduled, the researcher is required to pay $5 show-up compensation to subjects who show-up on time and do not participate in the study.

Subject Check In

For full service experiments, Xlab staff will start to check in participants about 5 minutes before the experiments. Subjects will be seated and ready to start the experiment by the start time. Request for special check in procedures (seating arrangement, etc.) should be submitted through the experiment Request Form.

Subject Payment

Researchers are required to provide participation fees and incentives in the experiment. Please provide funding information in the Experiment Request Form. Xlab staff can process subject payment by check, Amazon.com Electronic Gift Code, and UC Berkeley Prepaid Virtual Visa. Amazon gift codes must be flat fee, whereas Virtual Visa and check can be variable payment.
UCB managed funds: Xlab staff can arrange the fund transfer with your financial manager.
Non-UCB managed funds: An advance deposit against Xlab issued quote is required.

Experiment Session Time

Researchers must determine the experiment duration for each session accurately. Please include time for explaining study instructions, distributing and collecting consent forms, distributing login name, experiment number, or passwords (if applicable), and a buffer time for any unforeseen event. Participants must be released at the end of the experiment session time so participants can accurately schedule their busy schedules.
Set Up Time: Schedule 30 minutes of set up time at the beginning of each day's session apart from experiment session time. Xlab preconfigures the systems according to the researcher requests (desktop shortcuts, installation of required software, headsets, etc.). Researchers may use this time to get organized and get consent materials ready. Any supplies for the experiment (consent forms, scratch paper, calculators, etc.) must be provided; Xlab only has a supply of pens that can be used during the experiment.
Payment Time: Add at least 30 minutes to the end of the session for subject payment. This is as unpaid transition period and cannot be used for the experiment. For variable payment sessions, the researcher must send Xlab staff payment information when it is ready. The pay file must be an excel spreadsheet and include subject computer station number in one column and final payment amount in another. Once the payment checks are ready, Xlab staff will distribute them to subjects.

Available Software

  • MediaLab
  • DirectRT
  • Inquisit
  • Z-tree
  • E-prime
  • Python
  • Matlab with Psychtoolbox
  • Browsers: Mozilla Firefox, Chrome, MS Edge
  • MS Office: Word, Excel, Powerpoint
Graphic for In-lab study workflow: Researhcer and Xlab set up lab -- Xlab check in and seat participants -- Researcher gives instructions and obtains consent -- Researcher runs experiment -- Xlab distributes payment.

Researchers who wish to handle any aspect of their experiment as self service must have CPHS clearance to do so. Xlab is here to work with you to find the right amount of service for your experiment. The Xlab staff is experienced and flexible and allows researchers to select the services they need. Researchers are required to include in their Experiment Request Form which services they want Xlab staff to conduct and which, if any, will be self service.

Subject Recruitment

Researchers who wish to recruit on their own will be given a Researcher Account for Sona-Systems, the website used to post studies and where participants sign up for study sessions. Researchers are in charge of creating their study information on Sona and opening study session timeslots; studies that are held in-lab must still submit a Schedule Request and receive approval before opening the timeslots to ensure there are no conflicts in Xlab. Some resources of online pools outside of UC Berkeley where researchers may recruit participants include: Amazon Mechanical Turk, TurkPrime, and Prolific Academic.

Room Reservations

Researchers who would like to run the experiments after Xlab hours can request for a key card access to the lab.

Subject Check In

Self service researchers must check in their participants before the start of the experiment. Researchers must also update participation on Sona so subjects who show up are marked as 'participated' and others as 'absent.' Participants will be asked to contact the researcher instead of Xlab if they have questions about scheduling or last minute conflicts.

Subject Payment

Researchers conducting their own payment may do so with the appropriate clearance, such as petty cash handling, access to participant's information, etc.

Read our Sona-Systems Tips to help navigate Sona and expedite your study approval.

External Study

Participants take online experiments remotely from a personal computer. Subjects sign up and receive the study link from Sona, and are paid virtually. Automatic Credit Granting through Sona makes online Qualtrics studies much easier. Researchers may choose which services to have Xlab staff handle, from full service to self service.

Online Tools:
  • Qualtrics - is a powerful, full-featured web-based platform for creating, sharing and conducting online surveys. Berkeley provides access to all basic features of this software to all campus members. Online Training and Resources are available at D-Lab website
  • Inquisit Web - is a powerful tool for designing and administering rich psychological tests and experiments remotely over the web. Xlab has two web licenses that is shared between the Haas Behavioral Lab and Xlab. It is available to Xlab researchers on a first-come first serve basis for Xlab/Behavioral Lab researchers. Fill out the Inquisit Web License Access request form. Approval would depend on when and for how long you need the license. If approved, we would work with you on uploading the Inquisit files and downloading the data.

Xmobile experiments are completed directly from the participants' mobile phone. Xmobile experiments may require the installation of applications and in-lab participation. Participants must have smart phones that are capable of certain applications (e.g. Android, iPhone). Participants will be paid virtually. Researchers may choose which services to have Xlab staff handle, from full service to self service. More information is available at the Xmobile Project website

The Xportable program allows researchers to conduct their studies anywhere on campus. Researchers check out Xlab machines that are configured similar to the laptops in lab. Researchers are responsible for all machines loaned to them, and agree to return all computers by agreed upon date. Xportable experiments are self service; Xlab staff cannot provide any assistance in installing, testing, or debugging software on these computers. To request for laptops, please fill out the xPortable Request form.