Item pool confusion

VJay

Hey everyone :)

I am new with openSesame and very thankful for this great openSource program and Chapeau! I am very impressed by the program.

I am trying to build an experiment and I am stuck with 2 concrete questions: The experiment itself is straight forward. People simply have to rate statements. Now I built a list with, lets say 300 statements within 3 categorieys (100 each). I divided these statments in 10 blocks. In the first block I would like to show 8 statements out of the category 1 + 8 statements out of category 2 and 8 statements out of category 3. This will change for the next block (12/8/4). Can I select a specific number of items out of a pool?

Additionally (2. question) I do not want a statement to be repeated. If its used. Its used. So in the second/3rd/4th blocks Items should not be repeated. Is it possible to somehow cross-out items if they have been seen once?

Does somebody know how to implement that or has something similiar to that ?

Thank you for you help, greetings Vanessa.

sebastiaan

Hi @VJay ,

There are many ways in which you could implement this, but I guess what I would do is define the statements themselves in an inline_script as randomized lists of strings at the very start of the experiment. Something like this:

import random

category1 = [
    'a statement',
    'another statement',
    # etc.
]
category2 = [
    'a statement',
    'another statement',
    # etc.
]
category3 = [
    'a statement',
    'another statement',
    # etc.
]

random.shuffle(category1)
random.shuffle(category2)
random.shuffle(category3)

Then, in the block_loop you create a column "category", which indicates the category that you want to sample from. If you want to have a 12/ 8/ 4 ratio, this would simply be implemented by having 12 rows on which the column "category" has the value 1, 8 rows with 2 and 4 rows with 3.

Finally, at the start of each trial_sequence, you have another inline_script that takes one statement from the correct list and assigns it to an experiment variable. Like this:

if var.category == 1:
   var.statement = category1.pop()
elif var.category == 2:
   var.statement = category2.pop()
elif var.category == 3:
   var.statement = category3.pop()
else:
   raise ValueError('category should be 1, 2, or 3')  # sanity check

Does that make sense?

— Sebastiaan

VJay

I will try out :) thanks a lot

VJay

Dear Sebastiaan,

I tried your advices now in diffrent ways, but I am still stuck. somehow openSesame is not taking the statements which I defined at the very beginning of the experiment as you said. Is it possible to check somehow if the lists is working ? I also created in the block loop the category. Here I am not complety sure if I understood it right what you suggested. It looks like this (teil2) now in my openSesame profile.

• I am getting this error: exception message: category should be 1, 2, or 3

Can somehelp out again ?

Kind regards, Vanessa

lvanderlinden

Hi Vanessa,

The error message comes from the fact that you have some empty rows in your block_loop item. You can remove them by selecting them (from row 7 to 12), right click, "remove 6 row(s.)"

Note that in the above example, the categories are divided equally, that is, 33% each.

Cheers,

Lotje

lvanderlinden

Hi @VJay ,

To show the statement instead of the category number, you should change the sketchpad content accordingly. Write [statement] instead of [category]

Hope this helps!

Cheers,

Lotje

VJay

Dear Lotje,

Yessss.. there was the logical mistake. Now it works like clockwork!!

Thank you!!

Vanessa