Dear SPM List,
I am relatively new with SPM and face a problem with the contrasts
after performing a two-sample t-test.
My design is really simple:
I have two groups (group A and group B)
There are two conditions in each group (conditions 1,2).
It's a block design.
The problem is the following:
When I make the contrast: (Condition 1 > Condition 2) (Group A >
Group B), I obtain the exact
same contrast than when I perform (Condition 2 > Condition 1) (Group B
> Group A).
What is strange is that when I ckeck the contrast (Condition 1 >
condition 2) and (Condition 2 > condition 1) using a one sample t-test
in each goup, the contrasts are different from one another.
I checked if the contrasts at the first level analysis were corrects,
if the onsets were properly set. Now I don't know
where the problem is.
Maybe I missed something when performing the two sample t-test...
Thanks for your help