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Thread: Fixed trials within randomized (BGR) blocks?

  1. #1
    Join Date
    Oct 2006
    Posts
    12

    Fixed trials within randomized (BGR) blocks?

    I was thinking maybe someone will be able to help me with my problems here : I'm trying to run an ER task that design like that:
    We have 12 blocks of slides, 5 slides in each block. While the same 5 slides that make up each block need to be the same across participants, the block order needs to be randomized.
    We also need a sound label to be presented before slides. For example, "1A, 1B, 1C, 1D, 1E" need to be presented before each of the slides in the first block, and "2A, 2B, 2C, 2D, 2E" need to be presented before each of the slides in the second block. Although we're randomizing the blocks, we are NOT randomizing the sound labels. In other words, "1A, 1B, 1C, 1D, 1E" need to precede the 5 slides in the first block for each participant, the actual block of slides will be different for each participant due to randomization.
    i don't know how to solve this problem so if someone has a solution pls let me know
    thanks
    maya
    Last edited by jarvis24; 11-17-2006 at 10:31 AM.

  2. #2
    Join Date
    Nov 2005
    Posts
    3,318
    Want to be sure I understand the basic problem here. The way I read it, the trouble is having blocks randomized but keeping a set of fixed intros, where one precedes each of the trials within the randomized blocks. E.g., Say I wanted to show a block of 5 letters and a block of 5 numbers, randomizing the order of those two blocks and maybe even the trials within those blocks. That's usually no problem--the catch here is that I want to show "trial 1" before the first trial, no matter whether it's a number or a letter. Then "trial 2", "trial 3" and so on. Is this the problem? If so, I've attached a test input file for you to check out that addresses this at the most basic level. Take a look and see what think.
    -Blair
    Attached Files Attached Files

  3. #3
    Join Date
    Oct 2006
    Posts
    12
    hi
    i have been trying to get your help in this matter
    pls help me with that
    it didnt work and we suppose to start running subjects really soon
    thanks
    maya

  4. #4
    Join Date
    Nov 2005
    Posts
    3,318
    I need to know why the solution I offered doesn't work. If you can show me that you understand what I was suggesting and exactly where it falls short, I'll do my best to help fix it or come up with an alternative.

    Just so you understand where I'm coming from--when working out complex problems like this, I prefer to work with a very small input file with just enough elements to illustrate and solve the dillemma. If we can figure out a solution on a very small scale like this, then we can apply that to your larger input file.

    -Blair

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