Hi there,
I'm not sure how to set up a comparison in a 3 level design. Subjects underwent ten 5 minute
scans, and in each, they were presented novel stimuli. These novel stimuli were repeated 2 scans
later, so the novel items (nov) in scan 1 were presented again (repeatNov) in scan 3 (along with
more nov items), the ones in scan 2 were repeated in scan 4, etc.
So, for 15 subjects, I have 10 scans each, and want to do a contrast looking at repeatNov-Nov, so
repNov3 vs nov1, repNov4 vs nov2, repNov5 vs nov3, ...
I assume I set this up in some way as a paired t-test in a second level for each subject, then
combine these in a 3rd level....
But things get trickier... I want to look not just at mean changes, but also at linear decreases
across the scans and exponential decreases across the scans for this contrast. I know how to do
this if the repeats were in the same scan and I could set up the contrast in the first level, but...
um...
Thanks!
Robin
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