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Thread: Random Time Intervals

  1. #1
    Join Date
    Mar 2006
    Posts
    3

    Random Time Intervals

    Hello-

    I want to create a reaction time task with DrectRT and would like the stimulus to have a random interval of time between displays. I know you can set a fixed interval in styles (under options). Is there a way to make the interval a random amount of time between given boundaries limits?

    Thanks-
    Joe
    Last edited by jarvis24; 07-11-2006 at 05:17 PM.

  2. #2
    Join Date
    Nov 2005
    Posts
    3,328
    Hi Joe,
    Do you want them be be truly random or do you want oto ensure that there are an equal number of various values (e.g., 500, 1000, 1500)?
    -Blair

  3. #3
    Join Date
    Mar 2006
    Posts
    3
    Hello-

    Really, it doesn't matter to me. I just don't want our subjects to be able to get into a pattern of hitting the response key after a fixed period of time. If you could explain how to do both options that would be great.

    Thanks.

  4. #4
    Join Date
    Nov 2005
    Posts
    3,328
    OK, check this out:

    http://www.empirisoft.com/directrt/h...dom_values.htm

    e.g., you should be able to just enter something like rand(500,1000,1500) in your Time column.

    Hope that helps,
    Blair

  5. #5
    Join Date
    Nov 2005
    Posts
    3,328
    [edited from related support email]
    I am interested in setting different inter-trial intervals for a lexical decision task that I am programming. I believe that inter-trial interval is set in the Options window under the Style Editor, but I was only able to apply one inter-trial interval to all the trials in my experiment. I would optimally like to have Direct RT randomly select an inter-trial interval from a list of a few (e.g., 4) – do you know if this is possible?
    As above.

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