Pseudorandomization

arsal_go

Hello everyone,

I was lurking around the forum trying to read past posts on this regard. As far as I am concerned, the current version of OSWeb still does not supports pseudorandomization as a typical loop/constraint feature, right? Is there any other way to implement pseudorandomized trials in OSWeb? I am a complete disgrace when it comes to coding, so I would appreciate it if you could answer me like I was a 6 year old (disgraceful) kid.

In my case, I want to apply pseudorandomization to a lexical decision task with 120 words and 120 pseudowords (so, 240 trials). I have two factors (A [2 levels] x B [3 levels]) and what worries me is to have more than two items of the same B level in a row (I don't care about factor A).

If it is not possible to do this online, I will just go with the total randomization, and perhaps check for carry-over or presentation effects in the data analysis.

Thank you! :')

Best

eduard

Hi Arsal,

If I am not mistaken, importing excel sheets as loop tables is supported in Osweb. So even if the advanced loop operations are not supported, you could generate the sequences outside of the Opensesame (with the software of your choice), and inside Opensesame import it to populate the loop table with those settings. See here.

Hope this helps,

Eduard

Fab

Hi@arsal_go,

@eduard is right, OSWeb supports the importing of csv files in the loops since version 1.4. If your pseudorandomization is demanding, the best option may be to create your stimuli sets offline (using the programming language of your choice) and to set your task to import one (for example based on the subject number).

If you're at ease with Javascript programming, you could also read a generic csv file using csvParse javascript library (available from OSWeb 1.4) to parse its content into variable, manipulate them using Javascript programming to achieve the pseudorandomization you're after, and then populate the loop table. Note that this method will require that you do some coding and that, depending on how constrained the pseudorandomization is, there is a risk that the task gets stuck if no solution is found.

I posted something on this issue a while back, that you may find useful if you decided to go down the second route: https://forum.cogsci.nl/discussion/7413/demo-how-to-parse-a-csv-to-populate-a-loop-osweb-1-4

The first route is simpler in terms of the programming of the task, though.

Hope this helps,

Fabrice.

arsal_go

Dear @eduard and @Fab

Thank you so much for your responses :). I thought importing csv files was not supported, but that's because my OpenSesame version was not updated! I am going to try and go with Eduard solution, since I am lacking knowledge on Javascript programming, but thank you so much for that link to your thread, it's incredibly useful.

Best,

Arsal