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Thread: Startle Probe and TTL to Biopac?

  1. #1
    Join Date
    Nov 2005
    Posts
    3,323

    Startle Probe and TTL to Biopac?

    [edited from support email]

    Thanks for the information. We have set up the experiment and know how to connect the hardware. Right now our question is much simpler, but we can't seem to figure out the response.

    Basically we have set up an experiment in which we show participants 36 movies, each of which is 7 seconds long. After each movie, respondents are presented with 9 questions. We structured the program so that each movie and the nine questions that follow are in separate ML questionnaire. We then programmed the overall experiment to present the 36 questionnaires in random order. All of this is working fine.

    What we need to do now is tell ML that when it shows some of the movies we want to send a sound probe, a loud sound blast to startle participants. In addition, to make things more complicated, we need the sound to happen at three possible intervals. In an ideal world what would happen is that the participant sits in front of the computer and sometimes gets startled by the sound and sometimes does not. Sometimes the sound is sent at 3500 msec, other times at 5000 msec and other times at 6500 msecs. What is the best way to do this?

    I tried to program a line in each questionnaire that would be a sound file that would be played simultaneously with the movie, but I couldn't get it to work.

    To make things more complicated, we also need to program ML to send a TTL pulse to our Biopac equipment each time a sound file is played. We have the hardware configured, but don't know how to tell ML to send the TTL pulse. We are all real novices using the software because we had someone working in the lab who use to program everything, but this person is gone and we are trying to keep up with our regular duties AND do all this!

    Any help would be greatly appreciated.

  2. #2
    Join Date
    Nov 2005
    Posts
    3,323
    We recently added a built-in probe function like this to MediaLab. Check this post out for some samples and let us know how it works for you:

    Probe Samples:
    www.empirisoft.com/support/showthread.php?t=375

    And here a couple Biopac posts that involve TTL signals:
    www.empirisoft.com/support/showthread.php?t=518
    www.empirisoft.com/support/showthread.php?t=571

    -Blair

  3. #3
    Join Date
    Apr 2007
    Posts
    10

    I am designing something similar, but using also DirectRT

    Check this answer, it may help you:
    http://www.empirisoft.com/Support/showthread.php?t=712

    Good luck!

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