Details of different worker types
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Following Amazon Mechanical Turk’s terminology, a worker in JATOS is a person who runs a study. Different worker types access a study in different ways. For example, some workers can run the same study multiple times, whereas others can do it only once.

  Jatos Personal Single Personal Multiple General Single General Multiple (since v3.3.2) MTurk
Typical use During study development Small targeted group, each one of them gets a link Small targeted group of workers who pilot the study or need to do it multiple times Bigger groups but with less control; link shared e.g. via social media Bigger groups and where the workers need to do it multiple times For Amazon Mechanical Turk
Created when? Together with the JATOS user By yourself in the Worker Setup By yourself in the Worker Setup On-the-fly whenever someone uses the link On-the-fly whenever someone uses the link On-the-fly after a MTurk worker clicked on the HIT link
Repeat the same study with the same link (has no links)
(keeps the same worker)

(creates a new worker each time)
Run different studies with the same worker
Supports preview of studies
Possible bulk creation
Run group studies

Jatos Worker

Jatos workers can run any study as many times as they want.

Jatos workers run a study (or any of its components individually) by clicking on the Run buttons in the GUI. Jatos workers are usually the researchers trying out their own studies. Each JATOS user (i.e., anybody with a JATOS login) has their own Jatos worker.

Personal Single Worker

With a Personal Single link a study can be run only once (*But see Preview Links). You can think of them as personalized links with single access. Each Personal Single link corresponds a Personal Single worker.

Usually you would send a Personal Single link to workers that you contact individually. Each link can be personalized with a Comment you provide while creating it (e.g. by providing a pseudonym).

Personal Single links are useful in small studies, where it’s feasible to contact each worker individually, or (e.g.) you want to be able to pair up several results (either from the same or different studies) in a longitudinal design. You can create Personal Single links in bulk by changing the Amount value.

GUI Screenshot GUI Screenshot

Personal Multiple Worker

With a Personal Multiple link the worker can run a study as many times as they want. Each Personal Multiple link corresponds to a Personal Multiple worker.

You could send Personal Multiple links to your pilot workers. Each link can be personalized with a Comment you provide while creating it (e.g. by providing a pseudonym). You can create Personal Multiple links in bulk by changing the Amount value.

General Single Worker

This link type can be used many times by different participants to run a study but only once per browser (*But see Preview Links). Each time the link is used a new General Single worker is created on-the-fly.

You could distribute a General Single link through twitter, a mailing list or posting it on a public website. It is essentially useful for cases where you want to collect data from a large number of workers.

Keep in mind, however, that JATOS uses the browser’s cookies to decide whether a worker has already accessed a study. If someone uses a different computer, a new browser, or simply deletes their browser’s cookies, then JATOS will assume that it’s a new worker. So the same person could (with some effort) use a General Single link several times.

General Multiple Worker (since version 3.3.2)

A General Multiple link is the least restrictive type and can be used many times by different participants to run a study. The difference to a General Single is that the General Multiple link can be used repeatedly even in the same browser. Each time a General Multiple link is used a new General Multiple worker is created on-the-fly.

MTurk Worker

MTurk workers access a study only once, through a link in Amazon’s Mechanical Turk (AMT). Each MTurk worker in JATOS corresponds to a single worker in AMT.

DATA PRIVACY NOTE: If the same worker from AMT does two of your studies, the two results will be paired with the same MTurk worker in JATOS. This means that you could gather data from different studies, without your workers ever consenting to it. For this reason, we recommend that you delete your data from JATOS as soon as you finish a study. This way, if the same worker from AMT takes part in a different study, they will get a new MTurk worker, and you will not be able to automatically link their data between different studies. See our Data Privacy and Ethics page for more details on this.

A normal General Single or Personal Single link is restrictive: once a worker clicked on the link - that’s it. JATOS will not let them run the study twice. But in some cases you may want to distribute a link and let your workers preview the first component of your study (where you could e.g. describe what they will have to do, how long it will take, ask for consent, etc). Often, workers see this description and decide that they want to do the study later.

To allow them to do this, activate the checkbox Allow preview (this will add a &pre to the end of the URL). Now your workers can use the link as often as they want - as long as they don’t go further than the first component. But once the second component is started, JATOS will restrict access to the study in the usual way as it is for General Single and Personal Single workers. This means that you’ll get an error if you try to use the link again to access the study.

GUI Screenshot