Randomize pair of stimuli between subject but maintain same pair within subject

ireneruizp

Hi everyone, I've read something similar in another discussion but I was wondering if anyone coul help me because they're some things I don't understand. I'll try to explain my experiment as well as I could, English is not my first language.

I have an associative learning task in which participants should learn the value of several stimuli. I have 20 stimuli (10 images of cheese and 10 images of wash machines) and I want them to be presented with a random value picture (high or low value). I have three columns, one for stimuli, one for correct value and another for incorrect value. I want to randomize which value pairs with which picture between participants (same number of hight and low values) but they have to see the same pair in every block (the pair will be shown untill they get a minimun accuracy). So I want pairs images to be randomize between participants but maintain same pairs within subject.

Thank you so much for your help :)

DahmSF

Hi Irene,

i am not sure whether i really got what you are looking for, but from your description, it appears like you only need to define 2 variables in your loop (one for image, one for value).

This may looks something like that:

image value

cheese low

cheese high

wash low

wash high

Hope that helps

ireneruizp

Thanks for your answer. Yes, but I need to take ten randomize rows of cheeses and ten randomize rows of washes for each participant, but the pairs 'stimulus-value' must maintain the same for the participant. If I just create two columns and randomize pairs one participant would see, for example, 'cheese 1-low' in one trial but 'cheese 1-high' in another trial. I hope I explained my self.

DahmSF

Hi Irene,

if I got it right, then you will need a third variable that includes the numbers from 1 to 10 as there are ten difference cheeses. Actually, OpenSesame can make the multiplication to 40 rows then!

A second thing you mentioned is the order of the stimulus appearance, right? If you want the same order of stimuli for each participants, you should not use 'random' but 'sequence'. Just create your own sequence in the rows that will be equal for all participants.

Saludos

Stephan