Hi all, 
 

I need to set up a study in which participants are allocated to videos eliciting emotions interspersed with commercials. So, I want participants to see an emotional video to elicit/prime a particular emotions and then present an advertisement afterward (and repeat this several times).
I have several videos that need to be shown: 5 sad videos, 5 disgusting videos, 4 neutral videos and 10 commercials. All these stimuli should be seen by the participant only once.

The goal is to do a within-subjects design in which participants will be presented with two blocks of sad videos interspersed with commercials and two blocks of disgusting videos interspersed with commercials. 

Below is an example of a possible presentation order:​​​​​​​

Presentation scheme: tsad1 - ad1 - sad2 - ad2] - neutral1 - sdisgust1 - ad3 - disgust2 - ad4] - neutral2 - ssad3 - ad5 - sad4 - ad6 - sad5 - ad7] - neutral3 - sdisgust3 - ad8 - disgust4 - ad9 - disgust5 - ad10] - neutral4

Conceptual scheme: pblock sad with two videos] neutral tblock disgust with two videos] neutral tblock sad with 3 videos] neutral wblock disgust with 3 videos]

Here, I start with a block of two sad videos but it may start with a block of two disgusting videos (ie., the two first blocks presented above would be flipped). It may also be possible to start with the block of 3 sad videos or with one of 3 disgusting videos (ie., the 3rd and 4th blocks respectively). The important part is that the order of the blocks cannot have the same emotion twice, it must have one interspersed with another (e.g., sad and after disgust).

The toughest part is that I want to randomly present the ads across the sequence. So, we could start with ad1 or ad8 (only present the same ad once). Also, I want to randomize sad videos across both sad blocks. And the same for disgust videos, I want the 5 to be presented randomly across both disgust blocks. Finally, I want the 4 neutral videos to also be randomly presented.

I hope this strange design is clear to you. Any idea/suggestion on how to do this without having to write hundreds of “Ifs” in the survey flow? I would really appreciate it. 

Thank you very much! 
Catia Alves