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randomize every trial but the first one

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  • randomize every trial but the first one

    Hey there!

    As far as I understand, one can randomize all events and "exclude the first one" but this option does not seem to be available for the trials within a block.

    Background information:
    Why do I want this? To play an audiofile throughout one block, starting with the first trial, ending with the last response of the block. So the first trial should be at a fixed position to start the audiofile under the condition to "keep playing until the block ends" - as available in superlab.
    Because if I attach the audiofile to each trial (so it does not matter which one starts first) the experiment stops after a few trials and superlab shuts down with an error.
    Starting the audiofile prior to the block in a different block would work, because there is the option of "keep playing until the audiofile ends". BUT processing time of the experimental block depends on the speed of the participant and so the length of time needed for the block varies, which means the sound file could be playing for longer or not long enough.

    Question:
    Did I miss the option of putting only one trial to a fixed position and randomize all other ones? Or do you have any other idea how to solve this problem?

    Tanks for helping!
    Svea

  • #2
    When you say that SuperLab “shuts down with an error”, can you please post a screen snapshot of that error message?

    Regarding the design of the experiment, a good approach to do it would look like this:
    ”My Block" contains 2 trials:

    “My Block” —> “Audiofile trial”
    “My Block” —> “List-based trial”
    The “Audiofile trial” contains a single simple event that does not use a list. It is an audio event set to “keep playing until block ends”.

    The “List-based trial” contains an event that uses a stimulus list. It may also link to other events, such as a simple cue, or a “gather response” event. But this trial should use a stimulus list to create the “bulk” of the trials for the block “My Block”.

    Then you do the following:
    1. Disable randomization in the Block Editor.
    2. Double-click on the trial “List-based trial” to edit. In the Trial Editor, click on the List Access tab and enable randomization.

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