Frequently Asked Questions

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Q: Where is the data?

A: Data is usually saved in a .txt or .csv file in the directory the script runs in.

Q: Is there a version available for the Mac?

A: PEBL Currently offers a compiled version (0.11) that works on 64-bit OSX. While there is no technical limitation preventing PEBL on 32-bit OSX, nobody has created it yet.

Q: How do I launch a script?

A: The easiest way is to start the launcher. In windows, this can be done either from your main menu, or by navigating to the>My Documents\PEBL-exp.0.09 directory and clicking on the shortcut there. If you want to just launch a specific script with preset parameters (screen size, etc.), you can launch the script directly from a shortcut or batch file (see below)

Q: When I try to launch a PEBL script, nothing seems to happen. What can I do?

A:This could happen for a number of reasons. The first thing you should look at is the 'Errors and Messages' window at the bottom of the launcher. Scroll down to the bottom and see if there is a message that helps you track down what happened. The same text is found in a file stderr.txt that will be located in the directory you started the script.

Q: PEBL crashes immediately when I try to run a script. What can I do?

A: This might stem from the video mode you used, especially if you are running on a laptop with limited display ranges. Try two things (on Windows): First, uncheck the 'full screen' mode; next, change the driver setting to windb from directx. Together, these will often fix the problem. You may need to change the script to a different resolution to fit your screen if you want it to work in full-screen mode.

Q: How can I set the screen size to best fit my screen?

A: Although the PEBL launcher allows you to set screen resolution, these can get overridden inside a PEBL program by setting the gVideoWidth and gVideoHeight variables, such as:

 gVideoWidth <- 800
 gVideoHeight <- 600

So, set these variables in a script and it will always use that screen size.

Q: I'm having trouble with the launcher. It hangs when I try to run a script, I have to kill the launcher with the task manager, after which my script will run, but with problems. What is wrong?

A:This happens on some specific computers, and we haven't tracked down why. It is most likely a problem with the launcher, and not PEBL itself. Right now, your best solution is to bypass the launcher and run scripts directly from a batch file or shortcut (see below)

Q: How do I launch a script directly, bypassing the launcher This can be done by writing a batch file or creating a shortcut. You may want to do this so you can set different options directly without worrying about setting the right options every time you launch the script. You can also use this to launch PEBL from another program (i.e., if it is one of a series of tests you are conducting controlled by some other piece of software). To create a batch file, create a new text file and name it with a .bat extension, (for example, runme.bat). If you want to run an experiment called experiment.pbl, copy the following into that file:

"c:\Program Files\PEBL\bin\pebl.exe" experiment.pbl

Make sure you add the quotes, and if you use non-US location for Program Files, change it there. You can add command line arguments to specify different options at runtime: below).

"c:\Program Files\PEBL\bin\pebl.exe" experiment.pbl -v sub1 --fullscreen --display 800x600 --driver dga

See more on command line options next. Note that when launching from the command line, you no longer have tha ability to enter a subject code. This can be done within the script too (see another question below).

Q: What command line arguments are available?

A: example: pebl experiment.pbl -v sub1 --fullscreen --display 800x600 --driver dga


 Invokes script and passes VALUE1 and VALUE2 (and any text immediately
 following -v) to a list in the argument of the Start() function.


 Initiates the global variable gSubNum to IDENTIFIER.  If not set here,
gSubNum is initiated to 0.


 Sets the video driver, when there is a choice.  For linux SDL, options xf86,
 dga, svgalib (from console).  Also controlled via environment variables.


 Controls the screen width and height (in pixels). Defaults to 640x480.
 Currently, only the following screens are supported:
 Note: Custom screen dimensions can be controlled in-script.


 Controls the pixel depth.  Depends on your video card.  Currently,
 depths of 2,8,15,16,24, and 32 are allowed on the command-line.

--windowed --fullscreen

 Controls whether the script will run in a window or fullscreen.


 Sets a language code which can be accessed during scripts.


 Turns on unicode handling, with slight overhead

Q:I'm not using the launcher--How can I specify a subject number within the script?

A: Somewhere after the line where you create a window with the MakeWindow() command, use the GetSubNum() command. So if the window is named gWin:

 gWin <- MakeWindow()
 gSubNum <- GetSubNum(gWin)

Q: How do I use non-ascii characters? When I try, I get little boxes in the text! When I try, the program crashes!

A: Two things are needed to display non-ASCII characters. First, you need to use a font that is able to display your characters. A number of fonts available in PEBL offer good support in this area, and the default fonts (Dejavu) handle most western characters with accents and such.. Next, you must save the PEBL script in UTF-8 format, WITHOUT A BYTE-ORDER MARK. Simply saving as 'unicode' often saves in UTF-16, which PEBL cannot read. Try using an editor like jEdit or notepad+, each of which offer saving in UTF-8.

Q: I want to translate the gambling task/card sort task into language X. How do I do it?

A: We offer internationalized versions of these tasks, where you simple need to translate a set of lines in a text file to localize the tests. Email the pebl-list mailing list to find out how.

Q: Are there norms available for the PEBL battery tests? A:

For some of the tests there are.  

Q: How do I cite PEBL?

A: There are a number of sources you can cite for PEBL, depending on if you want to cite the software code, the user manual, or a paper I have describing PEBL. A full list of publications that have cited or used PEBL is available at here

  • Mueller, S. T. (2010). PEBL: The psychology experiment building language (Version 0.11) [Computer experiment programming language]. Retrieved (ON DATE) from
  • Mueller, S. T. (2010). The PEBL Manual, Version 0.11. Lulu Press. ISBN 978-0-557-65817-6. Lulu Press.
  • Mueller, S. T. (2010). A partial implementation of the BICA cognitive decathlon using the Psychology Experiment Building Language (PEBL). International Journal of Machine Consciousness, 2, 273-288.
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