Hi,
I have a question about setting up my analysis for a block design task. I
have two conditions A and B, and a fixation cross in my experiment. For
technical reasons I can run only blocks A – fix – A … etc , B – fix – B …
etc. The main comparison I want to make is the comparison between the
activation of A and B.
I have (for now) 1 pilot subject who was scanned under condition A and B.
Condition A consists of 4 runs (A – fix A etc). Condition B also consists
of 4 runs (B – fix B etc).
Since I wanted to pool my data over condition, I started my analysis by
doing first level feats for both the 4 A runs and B runs, giving 8 first
level outputs. As EVs I defined:
A
Fix
A > fix
And similar for B.
In the second level analysis I grouped my data by performing 2 higher
level analyses, taking the four A or B first level analyses as inputs. The
contrast I chose consisted of one EV which I set to 1. I think this will
give me the mean for each of the above contrasts (resulting in 2 gfeat
dirs and 6 feat subdirs).
As a final step I wanted to use the feat subdirs from the gfeat dirs from
my second level analysis as inputs. Now I am bit puzzled, since I am not
sure how to define this contrast properly.
Can you help me solve this one? Thank you in advance,
Niels van Strien
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