The TrialStructure

Owned by Philip Quinlan
Last updated: 06 Aug, 2021
2 min read

Trial Order Presentation Information:

 

The trial presentation order is structured around sets and blocks. 

  • Sets are names that identify group of stimuli.
    • The program will randomly present a subset of the stimuli with the same set name to each participant. Identifying sets are useful when you have conditions, defined by stimuli, that you want to randomize the participants who are assigned to it.
    • Each scenario is assigned a “set” name in the stimFile.
  • To create each Block, the program will first follow the selection rules to select the correct number stimuli from each set and it will follow the randomization rules to randomize the order of the items within the set and randomize the order of the sets.
    • In the trialStructure.json file, there is a list called “trialStructure”. It contains the following information, FOR EACH BLOCK:
      • “blockNumber” (e.g., 1, or 2, etc.) Selection of items only occurs ONCE per block.
        • “setInfo”.  setInfo contains the following information for each setName:
          • “setName” (e.g., “is_is” or “1”)
          • “N” = [numberOfStimuliToSelectForTheBlock]
          • “selection” = [‘randomWithReplacement’ or ‘randomWithoutReplacement’ or ‘fixed’]
            • randomWithReplacement & randomWithoutReplacement = the program will randomly select the items with or without replacement.
            • Fixed = the program will select the items, starting from the first one encountered, successively to the last one, with each block picking up where the other left off.
          • Note that if N = the total number of items in the set and selection = withoutReplacement or fixed, then the program will select ALL the items in the set.
        • blockIterator: is a list
          • N = a number indicating how many times to repeat this block with the same items, but, perhaps, a different randomization.
          • randomizeTrialInSetOrder = [TRUE or FALSE]
            • TRUE = the order of the trials in each set will be randomized on every iteration.
            • FALSE = the order of the trials in each set will be presented in the order they were selected in the first iteration.
          • randomizeSetOrder = [fixed; randomFirst; randomAll]
            • randomFirst = the order of the sets in first iteration will be randomized, and the remaining iterations will be fixed to this order.
            • randomAll = the order of the sets will be randomized.
            • fixed = the order of the sets will be presented in the order they appear in setInfo
          • randomizeAllTrials = [true or false]
            • true = all the trials from all the sets are placed in a large vector and are randomized.
            • False = the randomization will follow the rules set out above in “randomizeSetOrder” and “randomPresentation”
          • The number of blocks in trialStructure specifies the total number of blocks.