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Thread: Place a time limit on a task?

  1. #1
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    Place a time limit on a task?

    [edited from support email]

    I have a DirectRT task (a n-back distraction task) that I need a set time-limit on. Is there any way to do this with a DirectRT csv file?

  2. #2
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    Yes, there is a way to do this in the 2006 version. See the attached "old or new" sample task for an illustration. It gives you 30 seconds to work on a set of math problems.

    How it works:

    You just create a comment column called !Meta. On any given trial you can create a time-based skip contingency by entering >tr:ms in the !Meta column--where tr is the trial you want to skip to and ms is the time (in milliseconds) after which you want to go there. The time-based skip is started at the onset of that trial and is executed when the time expires. The skip will occur no matter where DirectRT is but will wait until the current trial has been completed (it will not interrupt a session mid-trial).

    Say for example, you want to give a set of math problems and skip to the end, or to a different section after 30 seconds. If the end is at trial #100, then on the first trial, enter >100:30000 in the !Meta column. DirectRT will skip the subject to trial #100, after 30 seconds from the onset of the first trial.
    Attached Files Attached Files

  3. #3
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    If I want it to jump to the next trial after a certain amount of time for each trial, do I have to type in the number for each trial (for example 4:1000 if I want to switch to trial 4 after 1000ms) or is there a symbol that just means "next trial"?

  4. #4
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    You mean to skip out of a trial after x millliseconds have passed? If so, you could just apply a min-max value using the ! symbol in your style file. e.g., setting a min-max value of 0-1000! for that trial would do this (see Help on min-max).

  5. #5
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    Quote Originally Posted by jarvis24
    You mean to skip out of a trial after x millliseconds have passed? If so, you could just apply a min-max value using the ! symbol in your style file. e.g., setting a min-max value of 0-1000! for that trial would do this (see Help on min-max).
    Thanks. I didn't want to use the min-max first because it never seemed to work but I found another thread about that (in the Troubleshooting forum) with a replacement file to download and now it all works. Thanks again!

  6. #6
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    for anyone looking, that particular troubleshooting link is:

    http://www.empirisoft.com/support/showthread.php?t=94

  7. #7
    Is there a way to set a strict time limit on a group of trials? The "end" command in the "!meta" column seems perfect - except that it won't interrupt a trial when the time expires.

    Basically, we want to record the number of spacebar presses a subject makes (each press indicating that an intrusive thought has occurred) during a set amount of time, say 3 minutes. To keep track of spacebar presses, we've set up a DirectRT input file that has a series of identical, essentially contentless trials that are each terminated when the subject presses the spacebar. The problem with using "end" is that a subject might press the spacebar 10 seconds after the 3-min period has ended, 10 mins after it has ended, or never - which is why it would be great if there was a way to put a hard limit on the amount of time that can be spent on this block of trials.

    Any help would be greatly appreciated!

    Quote Originally Posted by jarvis24 View Post
    Yes, there is a way to do this in the 2006 version. See the attached "old or new" sample task for an illustration. It gives you 30 seconds to work on a set of math problems.

    How it works:

    You just create a comment column called !Meta. On any given trial you can create a time-based skip contingency by entering >tr:ms in the !Meta column--where tr is the trial you want to skip to and ms is the time (in milliseconds) after which you want to go there. The time-based skip is started at the onset of that trial and is executed when the time expires. The skip will occur no matter where DirectRT is but will wait until the current trial has been completed (it will not interrupt a session mid-trial).

    Say for example, you want to give a set of math problems and skip to the end, or to a different section after 30 seconds. If the end is at trial #100, then on the first trial, enter >100:30000 in the !Meta column. DirectRT will skip the subject to trial #100, after 30 seconds from the onset of the first trial.

  8. #8
    After a little more reading: I guess this can all be done in MediaLab using the d parameter with a .que file.

  9. #9
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    Nice, I always enjoy seeing an answer arrive before I do

    For anyone who's interested, this key press tracking feature in MediaLab is described in the following post:

    www.empirisoft.com/support/showthread.php?t=817

    But you are very right about that limitation in the DirectRT meta function. I think it's kind of annoying and will put it on the to-remedy list. Currently, meta functions only kick in between trials. It's because the timing loops within trials are so important, we avoid anything that could disturb them. Consequently, meta functions are assigned a lower priority such that they can only function between trials. We may have a way to change this in the next version so you can do it either way.
    Last edited by jarvis24; 09-12-2007 at 06:05 AM.

  10. #10
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    Last edited by jarvis24; 09-19-2007 at 03:14 PM.

  11. #11

    interrupting a trial

    I would like to create a compound stimulus trial in which a movie plays, and is followed by a picture. I would like to record a RT (from the point of the picture onset), clear the screen once the RT has been recorded, but keep the cleared screen up for a duration of time. The point being that each trial has to have a fixed duration (trial referring to the compound stimulus of movie + picture + response + cleared screen).

    I currently have this set up as a compound trial that shows the movie, then puts up the picture (rt:1,2,full,clear-1). I'm using this along with min-max! to automatically advance to the next trial at the end of the max period (e.g., 6 sec - even if there was no response). I thought this would make it such that the total time of the compound stimulus trial should not exceed 6 seconds. But upon testing, I see that the movie will play, then the second picture and response element will stay up for 6 seconds... creating a total trial length exceeding 6.

    The problem with using this method is that I have over 100 of these compound trials, in which the movies are all different lengths. Yet, I want each compound trial up for a fixed duration. The way I have it set up at the moment, this would require a new style to be created for each trial, with the appropriate min-max defined based on each movie length (max = 6000-movie).

    I was looking in the forums for a different way to do this, and I came across meta! This would be the perfect solution if meta was capable of interrupting a trial (>tr:6000). I could then set a very high max (all trials using the same style), and interrupt the trial after 6 seconds (counting from the onset of the movie).

    I'm running DirectRT 2006.2.28. Is there a way (using meta, min-max, or any other feature) that I can do this?


    Quote Originally Posted by jarvis24 View Post
    Nice, I always enjoy seeing an answer arrive before I do

    For anyone who's interested, this key press tracking feature in MediaLab is described in the following post:

    www.empirisoft.com/support/showthread.php?t=817

    But you are very right about that limitation in the DirectRT meta function. I think it's kind of annoying and will put it on the to-remedy list. Currently, meta functions only kick in between trials. It's because the timing loops within trials are so important, we avoid anything that could disturb them. Consequently, meta functions are assigned a lower priority such that they can only function between trials. We may have a way to change this in the next version so you can do it either way.

  12. #12
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    You have reinforced the point that the duration meta command would be especially useful if it could kick in during the trial rather than between trials. I see your point about the variable length movies and the fact that you could have to create different styles for each. As cumbersome as that is, I don't see away around it for this particular application--not if you want to keep the trial durations constant with variable length movie files. Hmm.

  13. #13

    !meta capability to interrupt trial in Version 2008.1.0.13?

    In the posting 9/12/2007 it was mentioned that the next version of DirectRT would possibly allow the !meta function a higher priority such that it would be able to function not only between trials, but would be able to interrupt a trial after a given amount of time.

    I am using DirectRT version 2008.1.0.13
    Does anyone know if this version allows for this? From what I have tried, it does not appear to, but I could be missing something so any confirmation would be helpful.

    My basic goal is to run open ended trials (rt:text) where participants have 15 seconds to enter a response. If they do not enter a response within that amount of time, I need the program to automatically proceed to the next trial after displaying the message "Please try to respond faster!" If there are any other suggestions as to how to accomplish this, that would be great as well.

    Thank you for your help,

    PA

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