Millisecond Forums

Randomize the order of trials

https://forums.millisecond.com/Topic35607.aspx

By nuttymenkk - 8/22/2023

Hi Dave,

I am wondering if I can randomize the order of several trials with the list function?
In my experiment, every trial contains a movie file, as well as two markers for the movie (one for the recording with biopac, and another for the recording with eyetracker).
I have eight movie trials in total, and I'd love to randomize the order of presentation of each movie in the experiment. I also want to have a fixation cross between the transition of each movie trial.
At the moment, I have created a list attribute containing all movie trials:

<list movielist>
/items = (trial.movie1, trial.movie2, trial.movie3, trial.movie4, trial.movie5, trial.movie6, trial.movie7, trial.movie8)
/selectionmode=random
/replace = false
</list>

If I create the following block, will inquisit randomize the order of movie trials without replacement? If not, is there a way to achieve randomization in this case? I have thought about using the item attribute, but I do need the markers for each movie file. Therefore, the item attribute is not suitable in this case. Thank you in advance for your help!

<block experiment>
/trials= [1=trial.fixation; 2= list.movielist; 3= trial.fixation; 4=list.movielist; 5 = trial.fixation; 6 = list.movielist;
7=trial.fixation; 8=list.movielist; 9 = trial.fixation; 10=list.movielist; 11= trial.fixation; 12= list.movielist;
13 = trial.fixation; 14 = list.movielist; 15= trial.fixation; 16 = list.movielist]
</block>
By Dave - 8/22/2023

nuttymenkk - 8/22/2023
Hi Dave,

I am wondering if I can randomize the order of several trials with the list function?
In my experiment, every trial contains a movie file, as well as two markers for the movie (one for the recording with biopac, and another for the recording with eyetracker).
I have eight movie trials in total, and I'd love to randomize the order of presentation of each movie in the experiment. I also want to have a fixation cross between the transition of each movie trial.
At the moment, I have created a list attribute containing all movie trials:

<list movielist>
/items = (trial.movie1, trial.movie2, trial.movie3, trial.movie4, trial.movie5, trial.movie6, trial.movie7, trial.movie8)
/selectionmode=random
/replace = false
</list>

If I create the following block, will inquisit randomize the order of movie trials without replacement? If not, is there a way to achieve randomization in this case? I have thought about using the item attribute, but I do need the markers for each movie file. Therefore, the item attribute is not suitable in this case. Thank you in advance for your help!

<block experiment>
/trials= [1=trial.fixation; 2= list.movielist; 3= trial.fixation; 4=list.movielist; 5 = trial.fixation; 6 = list.movielist;
7=trial.fixation; 8=list.movielist; 9 = trial.fixation; 10=list.movielist; 11= trial.fixation; 12= list.movielist;
13 = trial.fixation; 14 = list.movielist; 15= trial.fixation; 16 = list.movielist]
</block>

You can do this and it'll do what you want,but you don't even need any <list>. You can simply state your block's /trials as:

<block experiment>
/ trials = [
    1,3,5,7,9,11,13,15 = trial.fixation;
    2,4,6,8,10,12,14,16 = noreplace(trial.movie1, trial.movie2, trial.movie3, trial.movie4, trial.movie5, trial.movie6, trial.movie7, trial.movie8);
]
</block>



By nuttymenkk - 9/3/2023

Thank you so much Dave!