Hello,

I have 3 categories of stimuli, containing 5 stimuli each (so, there is a total of 15 stimuli). I want to run 24 trials total, but I do NOT want each category to be presented at equal frequency or ratios. I want the ratio of the stimuli from the three cateorgies to go in this breakdown 7:7:10. How do I do that?

In other words, I want to assign a frequency to each category, but then have Inquisit select them at random?

They syntax I thought might work is:

/trials=random[1-7=noreplace(category1);8-14=noreplace(category2);15-24=noreplace(category3)]

However, this does not tell Inquisit to select all the trials randomly because it defines trials 1 through 7 from category1 and trials 8-14 from category 2, etc. I just basically want to tell Inquisit the ratio: category1 should have 7 trials, category2 should have 7 trials, and category3 should have 10 trials (and select the trials in random order following this category ratio).

Any suggestions would be greatly appreciated! Thanks!

To sample trials in the desired proportions (7:7:10), you must simply enter them to the noreplace selection pool in the desired proportions. In your case that's

<block myblock>
/ trials = [1-24=noreplace(
    category1,category1,category1,category1,category1,category1,category1,
    category2,category2,category2,category2,category2,category2,category2,
    category3,category3,category3,category3,category3,category3,category3,
    category3,category3,category3)
    ]
[...]
</block>

Regards,

~Dave

Thank you Dave, that was quite helpful!!

-Valerie

+x

 

aliciay1 - 5/29/2020

Hi, 

To add to this question I was wondering if it is possible to manipulate the randomised selection so that no two same stimuli are selected in a row. Is it possible to do this? If so, how would that be established? 

For example: I have digits 1-9 selected from a list presented 24 times but I want the selection order to be randomised each time and ensure the same digit is not represented twice. Would a no replace function work in this instance?  


/items = (
trial.practice_go, trial.practice_go, trial.practice_go, trial.practice_go, trial.practice_nogo, trial.practice_go, trial.practice_go, trial.practice_go, trial.practice_go, trial.practice_go, trial.practice_go, trial.practice_go,
trial.go, trial.practice_go, trial.practice_go, trial.practice_nogo, trial.practice_go, trial.practice_go, trial.practice_nogo, trial.practice_nogo, trial.practice_go, trial.practice_nogo, trial.practice_go, trial.practice_go)
/ replace = false
</list>

Note: list of digits used for practice; tied to list.practice_trialtypes
<list practice_digitsequence>
/items = (
1, 2, 8, 4, 2, 3, 1, 5, 6, 7, 3, 4, 1, 2, 3, 9, 3, 2, 7, 9, 5, 4, 2, 5)
/selectionmode = list.practice_trialtype.currentindex
/resetinterval = 1
</list>

<block practice>
/postinstructions = (practiceend MWexamples1 realtask)
/trials = [1 = getReadyPrac; 2-25 = list.practice_trialtype]
/onblockend = [list.fontsizes.reset()]
</block>

Apologies if my question is not understandable. Any help would be greatly appreciated.
Thanks.