Exogenous cueing task
I have a randomization problem in OpenSesame.
I have to create a dot detection task driven by an exogenous spatial cue. Each trial will begin with a fixation cross (+) flanked by two blank squares on its right and left side. Then a cue (a face displaying one of 5 different emotions) will appear in one of the two squares in randomized order, followed by a dot presented in one of the two squares, in the same (valid trial; 70% of total) or in the opposite (invalid trial; 30% of the total) position as the cue (in randomized order).
I have 10 different faces for each facial expression.
So I have to randomize both the facial expressions and the trial validity considering that for each expression I should have 70% of valid trial and 30% of invalid trial.
I am not familiar with opensesame (I have used Matlab in the last studies) and I don't know how to do that.
Any help would be greatly appreciated!