My question is rather straight forward, I have subjects preforming two tasks, one where they only have to remember one set of instructions (single), and one where they have to remember two sets of instructions (dual). If I want to examine parts of the brain that are more active during the dual task than single (Dual>Single), I assume I would enter the times of the dual and single tasks as my EV's:
EV1 EV2
INPUT1: Single: 1 0
INPUT2: Dual: 0 1
and then make a contrast to examine dual greater than single:
EV1 EV2
C1: D>S -1 1
Each subject has multiple sessions as well. My question is, at which level should I define the dual greater than single contrast? I see two options:
1) First Level: input EV's and define D>S Contrast, mixed effects model, and pass the D>S contrast on to the next level --> Second Level: Fixed Effects model combine each subject's 6 sessions --> Third Level: Mixed effects model combine all subject's second level outputs.
or:
2) First Level: Input EV's, (define one contrast for each EV?) Pass the Cope directories for each EV on to second level --> Secold Level: Fixed effects model combining each subject's 6 sessions --> Third Level: Mixed effects model combining all subject's second level Outputs --> Fourth Level: Fixed (Or mixed?) Effects model with the two group level cope's as an input, setting up the following EV's and contrasts:
EV1
INPUT1: GroupSingle: -1
INPUT2: GroupDual: 1
EV1
C1: D>S: 1
I hope this was clear. Any advice?
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