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ehurel
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Stimulus randomization, Posted February 15th, 2019 #1
Hello everyone,

I'm currently working on a task randomizing pictures (4 types possible) and I would like to randomize their apparition but that the next stimulus would be not the same type as the previous one.
For example, I woud like to have :
B C A D A C D B

and not

B C A D D B C A.

I still need all of them to appear 12 times each.

Thanks in advance !
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eahuntley
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Posted February 17th, 2019 #2
Hello! I believe you can do that by creating stimuli lists and then setting the randomization to occur at the trial level (double click a trial, then select 'list access", and you can see your randomization options. It also allows you to pair stimuli from various lists if needed, while still randomizing the presentation). Good luck!
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ehurel
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Posted February 18th, 2019 #3
Thank you for your answer ! Unfortunately, I found these options but it does not allow me to choose the option to not present a stimuli from the same list as the previous one.
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eahuntley
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Posted February 19th, 2019 #4
Hello Ehurel! So you have created one stimulus list, and you would like to present it in a different randomized order for each trial, correct?

I believe you can do that by double clicking on the trial to get to the trial editor, clicking on "list access", and selecting "randomize every time the trial is presented." Then, in the block editor, select the number of times that you would like the trial to loop (it sounds like you want it presented twice).

Please let me know if I haven't understood your experiment / what you are hoping to do! You can also upload your experiment (or a simplified version of it) to this thread.
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ehurel
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Posted February 20th, 2019 #5
Thank you for your answer eahuntley!

I think I was not clear when I explained my problem.
My experiment is composed of 4 lists of stimuli (A B C D). Each of these lists includes stimuli from 1 to 12. This way, I have A1, A2, A3 etc.
I already managed to randomize the order of my stimuli from my lists (from 1 to 12, by presenting each of them only once). I also found how to randomize my lists to have A1, C12, B4, D8, A9, D6, B3, C8 and so on.

My problem is that I do not want to have in a succession the same stimuli list presented : for exemple, presenting A8 and right after A9. So in sum, I managed to produce : A9, B8, C6, D4, D3, A8, C7, B7. And I do not want those D4 and D3 one after the other.

I'm so sorry I was not clear earlier !

Thank you for your help !
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eahuntley
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Posted February 21st, 2019 #6
Hello ehurel - I think you *may* be able to achieve this type of controlled randomization by setting tags at the stimulus level, and then using parameters / conditional branching to tell SuperLab what it can display next. I will unfortunately not be of any help here, as I have not really explored these advanced features. Can anybody else offer more specific help? Good luck ehurel!
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