Monday, August 18, 2014

Testing personality with PEBL

In PEBL 0.14, we've included a free "Big-five" personality scale.  The test involves 50 questions that are responded to on five-point scale, and measure the five most common dimensions of personality: introversion/extroversion,  agreeableness, conscientiousness, emotionality, and  intellectualism.  The scale was originally developed by Goldberg (1992) and is available as art of the many resources at

To give some more details about the PEBL test, each question is provided on a single screen, and a response must be made before continuing.  Each screen includes the prompt, "How does this statement describe you?", and asks questions like
"I worry about things", with a five-point scale ranging from 'Very inaccurate' to 'Very accurate'. There is no ability to back up, and (unlike many on-line and paper versions) no ability to scan through other questions to improve consistency.  There are ten questions each for each of five dimensions, some coded positively toward the dimension and others reverse-coded.  All in all, the test takes at least ten minutes.
The test is located in the scales\ subdirectory of battery, and you run it by selecting the file bigfive.pbl in that directory.

50 questions may be too long, and so if you are only interested in a subset of questions, you can choose these in the options.  To do so, select the 'edit' button next to the parameters. By default, all sets are given (and the doext, doagr, docon,deoemo, and doint parameters are set to 1 (on).  Reset any of these to 0 to turn them off, and be sure to save the parameter set and use this new parameter set. In addition, you can select to randomize the order of the questions using the shufflequestions option.  This defaults to off (0), but you may have reasons to want a random order

Data format
Data are saved within the data\ folder of the scales\ folder.  One file, called bigfive.csv, saves a single line per participant with 50+ columns of data.  These inlcude the subject code, a timestamp and time needed to complete the test, as well as a column for every question asked (by question number). The last five scores give the summary values for each subscale (with proper reverse codings).  In addition, a second file is saved for each participant (data\bigfive-subnum.csv"), which contains a single row for each response, if more detail about order or timing is needed.  There is also a report file saved "data\bigfive-roport-subnum.txt") that provides the data in a bit more human-readable format.

To translate the test, you need to change two things.  First, you need to translate the questions.  These are saved in bigfive-EN.csv.  To translate, make a copy named after your two-letter ISO country code, and translate each line, making sure to keep the file in csv format.  It is probably easiest to edit in a text editor such as notepad++.  Then, change the country code in the launcher to run using the localized questions.

Also, you should change the instructions. The English instructions are saved at the end of bigfive.pbl script.  Edit this in a text editor, and find the text that looks like this:


   gInst <- accurately="" br="" can="" describe="" ow="" you="" yourself="">
Describe yourself as you generally are now, not as you wish to be in the future. Describe yourself as you honestly see yourself, in relation to other people you know of the same sex as you are, and roughly your same age. So that you can describe yourself in an honest manner, your responses will be kept in absolute confidence.

Indicate for each statement whether it is:
1. Very Inaccurate,
2. Moderately Inaccurate,
3. Neither Accurate Nor Inaccurate,
4. Moderately Accurate, or
5. Very Accurate as a description of you."

  gQuestionHead <- br="" describe="" does="" ow="" statement="" this="" you="">  gLikertoptions <- br="" ery="" inaccurate="" nbsp="">                       "Moderately Inaccurate",
                       "Neither Inaccurate nor Accurate",
                       "Moderately Accurate",
                       "Very Accurate"]

  gDebriefing <- br="" for="" hank="" in="" participating="" survey.="" this="" you="">}

Just edit, starting at the last }, to the end (replace the } ), assuming your language is "XX", and translate everything:

}elseif(lang=="XX") {

    gInst <- font="" instructiosn="" translate="">
   gQuestionHead <- br="" describe="" does="" ow="" statement="" this="" you="">   gLikertoptions <- br="" ery="" inaccurate="" nbsp="">                       "Moderately Inaccurate",
                       "Neither Inaccurate nor Accurate",
                       "Moderately Accurate",
                       "Very Accurate"]


Save this file, and send the translations back to the PEBL list so it can get incorporated into the newest version.

That is a basic overview.  If you use it, please cite both Goldberg and PEBL!


Goldberg, L. R. (1992).  The development of markers for the  Big-Five factor structure.  Psychological Assessment, 4, 26-42.

Mueller, S. T., & Piper, B. J. (2014). The Psychology Experiment Building Language (PEBL) and PEBL test battery. Journal of neuroscience methods, 222, 250-259.
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