Is it possible to have some trials occur more frequently?
in OpenSesame
Hello,
I am programming a cueing paradigm, following the beginners tutorial. In the tutorial, all conditions occur equally frequently. If I wanted 'valid' trials to occur 80% of the time and 'invalid' to occur 20% of the time, is there a way to do this?
Comments
Hi,
Yes, you can use the
weightoperation of theloopitem, which is described here:Essentially, you create a column, say
w, that indicates how often a particular should be repeated; in your case that would be 4 for valid trials, and 1 for invalid trials, resulting in an 80%/20% ratio. And then you add a lineweight wto the script of theloopitem.Does that make sense?
Cheers,
Sebastiaan
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Yes that makes perfect sense, thank you!
Hi,
I am using a similar paradigm (different % of valid/invalid trials) and included the weight function accordingly. Additionally, I'd like to randomize the sequence of all trials. Currently, the trials as defined in the rows of the loop-table are randomized but if I apply a weight to a row (e.g. 4), the trial defined in that row is always repeated 4 times in sequence.
Example:
word weight
bunny 1
carrot 4
The list [bunny, carrot] is shuffled but I want the list [bunny, carrot, carrot, carrot, carrot] to be shuffled. Is that possible without major changes of my loop-table?
Best, Stefanie
Hi Stefanie,
Yes, you can do that by adding a
shuffleoperation after theweightoperation! See also:Cheers!
Sebastiaan
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