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Forward

Read this if you want to find out more about Amazon Mechanical Turk (AMT) and how psiTurk can help you run web-based experiments on AMT painlessly and quickly. This section will also tell you what problems psiTurk does and does not solve to help you gauge whether it will be useful to you.

Understanding the psiTurk design philosophy: An analogy

Back before music was entirely digital people got their music on cassette tapes. To play the cassette you needed a player device (e.g., walkman or boombox). People would trade tapes, make copies of tapes, make mixtapes of their favorite songs. It was awesome.

psiTurk is like a player but instead of playing music, it plays (i.e., runs) experiments. You download and install the psiTurk application to your computer. This installs a command line tool psiturk which serves as a multi-function "player." It can (figuratively speaking) run, pause, eject, and configure a given experiment.

To make it useful though psiTurk needs something to play. You can download from our experiment exchange library an archive which contains all the files specific to a given experiment. You basically “play” the downloaded experiment using the psiturk command. You can easily switch experiments by downloading another experiment archive and “playing” it. Even better, you can make your own experiments by remixing others (borrowing code from projects in the experiment exchange) or building your own from scratch.

The goal of psiturk was to build the “player” so you can spend more of your time on the important part of your research… the experiment (i.e., mix tape)!

Oh, and in case you missed it, "playing" someone else's experiment posted to the experiment exchange basically means independently replicating it!

What is Mechanical Turk?

Amazon Mechanical Turk (AMT) is an online platform that lets you post a wide variety of tasks to a large pool of participants. Instead of spending weeks to run experiments in the lab, it lets you collect data of a large number of people within a couple of hours.

Some key terminology for understanding the AMT model:

  • HIT (Human Intelligence Task) - A unit of work (e.g. a psychology experiment)
  • Requester - The person or entity that posts HITs (e.g. a researcher or lab)
  • Worker - The person that completes HITs (i.e. a participant in your study)

Workers get paid a fixed amount for each HIT which is determined by the requester. Requesters can also make bonus payments to specific workers. Amazon collects a 10% fee for each payment.

What is psiTurk?

AMT provides some very basic templates that you can use to design HITs (particularly questionnaires), but these will most likely not serve your purposes as an experimenter. The psiTurk toolbox is designed to help you run fully-customized and dynamic web-experiments on AMT. Specifically, it allows you to:

  1. Run a web server for your experiment
  2. Test your experiment
  3. Interact with AMT to recruit, post HITs, filter, and pay participants (AMT workers)
  4. Manage databases and export data

psiTurk also includes a powerful interactive command interface that lets you manage most of your AMT activity.

How do I host a psiTurk experiment?

psiTurk experiments can be hosted on almost anything that has an internet connection and a public port, such as an office computer or laptop. You'll need a static IP to prevent your experiment's URL from changing. Users without one (e.g., most home users) can use a dynamic DNS service to forward a URL to their dynamic IP. Here's a list of free DDNS providers. You also may need to forward a port from your home routers to you personal computer.

Do I have to learn how to code?

Yes. To run your experiment in a web browser you need to have at least some basic web programming skills (especially using HTML, CSS, and JavaScript).

Fortunately there exist many resources and tutorials that can help get started. If you are completely new to web programming, you might want to check out Codecademy, for example, for interactive tutorials on building websites.

Once you mastered the basics, you can take advantage of the vast number of libraries and tools that can help you to build sharp and sophisticated experiments with the support of a large community of users. For specific questions, visit stackoverflow.com.

To get you started, psiTurk provides a fully functioning example experiment (Getting up and running with the basic Stroop task) that you can use as a template for your own study. psiTurk also includes a library of basic Javascript functions (psiTurk API) that you can insert into your code to handle page transitions, load images, and record data.