Hi Aliona,
The Sequence command and the related functions only care about the trials’ labels: if you yes-answer and no-answer trials share the same labels, you won’t be able to control their distribution. I suggest you include the yes/no bit of information in the trials’ labels, eg "critical-yes"/"critical-no" and "filler-yes"/"filler-no"
The pick function will pick the N next trials from a set: when you do pick(critical,8) and critical was set to randomize("critical"), it will pick 8 trials from a randomized set of all the trials labeled “critical”. Then you pass that to rshuffle, so those 8 trials will be interspersed with trials labeled “filler” in the order in which they were picked from critical
You could do that, in which case two critical-yes trials would always be separated by a critical-no, a filler-yes and a filler-no trial:
criticalyes = randomize("critical-yes")
criticalno = randomize("critical-no")
fillersyes = randomize("filler-yes")
fillersno = randomize("filler-no")
Sequence("demographics","etc",
rshuffle(pick(criticalyes,4),pick(fillersyes,6),pick(criticalno,4),pick(fillersno,5)),"break",
rshuffle(pick(criticalyes,4),pick(fillersyes,5),pick(criticalno,4),pick(fillersno,6)),"break",
rshuffle(pick(criticalyes,4),pick(fillersyes,6),pick(criticalno,4),pick(fillersno,5)),
"etc")
Don’t forget to add -yes/-no to your trials’ labels, and make sure the 5/6 match the number of different types of trials you have (I went with 17 filler-yes trials and 16 filler-no trials, for a total of 33 filler trials)
Jeremy