Dear Karl and dear All,
I am reading Friston et al. (2005) Conjunction Revisited. I understand
that if I want to find brain region that responds to the common component
between two conditions A (component 1 and component 2) and B (component
1), put in other words I perform a cognitive conjunction, I can select the
two contrasts corresponding to the two conditions A and B for conjunction
in SPM 5 Contrast Manager and then I set "Global" rather than "Conjuncion"
for "Null Hyp. to asses?".
With this procedure I test Null Hyp.: K=0 effects; K=1 effect and I infer
K >= 1 effects. The number of contrasts that share some uninteresting
effect (in my case only the contrast for condition A) is the number of
effects for H1 (in my case 1).
Are my procedure and its comprehension correct?
Many thanks in advance for your invaluable support.
Federico Tubaldi, Ph.D Student
Dept. of General Psychology
University of Padova
Via Venezia, 8
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office: 0039 049 8276671
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