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bmoriari
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Join Date: Jan 2013
bmoriari is on a distinguished road Posts: 1
Randomized Selection from Stimulus Lists, Posted January 31st, 2013 #1
I have a question about randomization. I have an experiment that contains 4 different lists of sentences that are currently set up as stimulus lists in the events. What I would like to do for the experiment is to have the subjects view 12 sentences from each of the 4 lists of sentences, for a total of 48 sentences. However, I cannot figure out how to make SuperLab pick each sentence randomly from among the 4 lists, I can only have it randomly pick 12 sentences from List 1 of sentences, then move on to randomly pick 12 sentences from List 2, and then so on. I know that I cannot randomize blocks, so is there any other way to accomplish what I need to do?
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MonikaT
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Join Date: Mar 2008
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Posted February 5th, 2013 #2
A sample experiment is attached to illustrate how to do this in SuperLab. Some points to be aware:


Five codes were created. One named "Trial Using List" with values A,B,C, and D. The other four codes are named "Done with Trial A (B,C,D)" with values "Yes" and "No"

Under the Block Editor:
  • Four macros were created to "Check if enough "A" (B,C,D) trials presented"
  • Under the Expression tab, it's set to "Number of trials Presented in this Block is greater than or equal to 2 trials (Trials marked with code :"Trial Using List" equal to "A")
  • Under the If True tab, the expression is "Change value of code "Done with Trial A" to "yes" in all trials in this block"
  • Another macro was created to repeat the block. This macro must run "After all the trials in the block have been presented"

Under the Trial Level:
  • An expression was created under the When to Present tab: "Number of times this trial has been presented is equal to 0 and Current trial's code "Done with the Trial A" is not set to "Yes"
  • Under the Code Values tab the correct code was tagged to their corresponding trial
Attached Files
File Type: sl4 bmoriari.sl4 (10.3 KB, 27 views)
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