Randomising without replacement - loops within loops


We are currently building an experiment where participants are required to do a visual working memory task, and an emotion intensity task in conjunction. Basically, they will be shown an image, then will perform 2 emotion intensity trials, and then are again shown an image which they must indicate whether this is the same or different image to the one presented initially. The emotion intensity task involves the presentation of one face, followed by another, and the participant must decide whether the faces were of the same or different emotional intensity.

Our problem is that we have 16 different trial types (16 combinations of emotional faces) and we want each of these shown twice in one block. We have one outer loop that has the excel sheet for the working memory task attached, and this is working fine. We then have two loops around each of the intensity task trials, the outer having the trial type excel sheet attached (that is, the sheet with the 16 combinations of trial types). In the inner loop, we have the stimuli for the trial type (for each, there are 24 options of stimuli pairs that can be shown).

We just need to be able to have 32 of the emotional intensity trials - 2 of each of the 16 trial types shown in the block - any insight into how to do this would be super helpful! I have attached pictures of the flow, and then what we have within each loop.

Thank you!

Hi Bianca, do you think you could edit your question above and try re-phrasing it for clarity. You clearly know exactly what you are doing but I for one struggled to comprehend the situation, and even exactly what the question was.

Think about writing it for someone who really has zero idea of your task. Good practice for writing the corresponding method section…