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Thread: Keeping image on-screen for a fixed window

  1. #1
    Join Date
    Nov 2005
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    3,318

    Keeping image on-screen for a fixed window

    [edited from support email]

    Is it possible to collect response data and maintain stimuli on the screen for a predetermined length of time? I am displaying pictures for either 1 or 3 seconds (and it is necessary that the pictures actually be viewed for that set amount of time), but I would like to obtain a response (yes/no) and a reaction time while the images are being displayed. It's critical that the pictures to be viewed for exactly 1 second or exactly 3 seconds. Is this possible?

  2. #2
    Join Date
    Nov 2005
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    See the section in the guide on "min-max" settings, specifically the use of the "full" keyword. e.g., if you have a min-max RT setting of 0-3000 for a given trial, you could simply request your RT like this:
    Code:
     
    RT:53,44,full
    Where full asks DirectRT to keep the stimulus onscreen for the full max value regardless of when the RT occurs.

  3. #3
    I am having a similar problem, and I think my problem stems from not knowing where to put the min-max durration.

    I am doing an N-back task and I want a letter to stay on the screen for 2 seconds and if no response is made I want to go to the next letter. Of course if a response is made I want to move on.

    I tried all permutations of adding min/max duration, clear-1, -1 (see below) and I can’t get it to work perfectly.

    0-5000! rt:1,2-1,full,clear-1

    i attached the first 2 lines of my program below. Any guidance would be much appreciated.

    jason

    Attached Files Attached Files
    Last edited by jcallaire; 09-07-2007 at 12:17 PM.

  4. #4
    nevermind i figured it out =p

  5. #5
    Join Date
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    May I ask what you figured out? Just in case anyone has a similar problem?

  6. #6
    Well the problem is the manual doesn’t tell you were to put the min-max info (at least where I was looking), and if it does then I apologize.

    So I figured it out by looking at other programs.

    (1) in the styles file I put 0-2000! in the min-max column (that’s where it goes!)

    (2) then in the “time” column of my program I have:

    rt:1,2,-1,clear-1

    This results in showing my stimulus for a max of 2 seconds. If the participant doesn’t respond then the non-response is recorded (-1) and the next stimulus is shown. If the participant responds with in the 2 second window the next stimulus is shown (clear -1).

    Now all I need are my button boxes (cough) and I can run this bad boy all day!



    jason

  7. #7
    Join Date
    Nov 2005
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    Great! Any chance you would be willing to zip and attache a sample of your N-Back task so that others could use it as a starting point for their own?

  8. #8
    Join Date
    Jan 2006
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    32
    Jason,

    would it be possible for you to upload the complete task? That would be very helpful!

    Thanks,
    Rene

  9. #9
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  10. #10
    Quote Originally Posted by jcallaire View Post
    Well the problem is the manual doesn’t tell you were to put the min-max info (at least where I was looking), and if it does then I apologize.

    So I figured it out by looking at other programs.

    (1) in the styles file I put 0-2000! in the min-max column (that’s where it goes!)

    (2) then in the “time” column of my program I have:

    rt:1,2,-1,clear-1

    This results in showing my stimulus for a max of 2 seconds. If the participant doesn’t respond then the non-response is recorded (-1) and the next stimulus is shown. If the participant responds with in the 2 second window the next stimulus is shown (clear -1).

    Now all I need are my button boxes (cough) and I can run this bad boy all day!



    jason
    Using Jason's method I created a 2-back task with 250 numbered stimuli (numbers 1-9). I used the !meta command to end it after 5 minutes. Correct answers are identified by pressing the spacebar (57) when a repeated value is presented or pressing nothing when a filler stimulus is present (-1).

    Attached; enjoy!
    Attached Files Attached Files

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