Wise listmates,

After beating my head against the wall for awhile and read-rereading the FIL manual, I’m at an impasse in how to set up a mixed design in SPM5 with a within-subject factor “feedback” (2 levels) and two between-subject factors “group” (2 levels) and “impairment” (2 levels).  Additionally, it’s my understanding that SPM5 is only capable of visualizing 2-way interactions, but there may be a way to set up a contrast to see the 3-way interaction of group x impairment x feedback?  How do I specify the 3-way interaction?  Is it just a difference of interactions below (i.e., [3 4] [3 2])?

Here’s what I can glean so far:

1.) Flexible factorial design

2.) Factors: subject (reserved word – not certain if this is a place marker for one of the two between-subject factors or separate factor altogether), feedback, group, impairment

(I’m I correct in specifying that the within factor is non-independent/equal variance, while the two between factors are independent/nonequal variance?)

3.) “Subjects” -> “Scans” -> “Specify Files” (2 .con images for each subject referring to the two levels of the “feedback” within-subject factor)

4.) “Conditions” -> completely stuck here!   I’ve found examples for single within- x between-factor, but nothing specifying single within- x two between-factors.

5.) “Main effects and interactions” ->

Main Effect 1 (feedback): 2

Main Effect 2 (group): 3

Main Effect 3 (impairment): 4

Main Effect 4 (subject/constant): 1

Interaction 1 (group*impairment): 3 4

Interaction 2 (group*feedback) 3 2

Interaction 3 (impairment*feedback) 4 2

Am I on the right track?  Any assistance or pointers toward walkthroughs or data examples pertinent to my needs would be most appreciated.

Cheers,

Jeff