Empirisoft Support

    Welcome to Empirisoft Support
Results 1 to 3 of 3

Thread: Randomize a STIMULUS withing a group (case 6149)

  1. #1

    Randomize a STIMULUS withing a group (case 6149)

    In my task I have 32 trials (16 each of 2 different stimuli) and I want to randomly have a tone play on 8 trials (4 for each stimulus; so it's not really random). Is there a way to have a random stimulus that is assured to appear on only 25% of the trials within a block? Thanks!

  2. #2
    Join Date
    Feb 2013
    Posts
    13
    I think the simplest way to achieve what you describe would be to simply add the tone to eight of the trials in the input file. Then, you can use within-group randomization to present the trials in a random order. That way, the tone will play for 25% of the trials, four times for each stimulus, but at a random position in the series of trials.

    So, to give a smaller example, you could set up something like the following (and then randomize the presentation order);

    1: Stim A, no tone
    2: Stim A, no tone
    3: Stim A, no tone
    4: Stim A, tone
    5: Stim B, no tone
    6: Stim B, no tone
    7: Stim B, no tone
    8: Stim B, tone

    Would that achieve what you wanted?

  3. #3
    thanks! That sounds pretty much exactly like what I did and it all worked.

Similar Threads

  1. Providing feedback on stimulus-response match in real-time (case 1671)
    By dlyoung in forum DirectRT v2018: How Do I...
    Replies: 2
    Last Post: 12-12-2015, 11:52 AM
  2. Between-Group randomization of questionnaires in an experiment file (case 6333)
    By mariegood in forum MediaLab v2018: General Questions
    Replies: 4
    Last Post: 03-14-2013, 12:10 PM
  3. Randomize Stimulus within a group
    By acwhite327 in forum MediaLab Older Versions: How Do I...
    Replies: 0
    Last Post: 11-02-2011, 11:13 PM
  4. two blocks of between group randomization
    By Michal in forum DirectRT Older Versions: How Do I...
    Replies: 4
    Last Post: 03-01-2010, 05:03 AM
  5. RT from end of stimulus rather than start of stimulus?
    By spaulding200 in forum DirectRT Older Versions: How Do I...
    Replies: 1
    Last Post: 12-17-2008, 05:01 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •