Dear FSL experts,
In my experiment, I have 2 stimuli in each trial, and each stimulus consists of 4 possible conditions. After the 2nd stimulus, subject was asked to report a behaviour scores related to the 2nd stimulus.
(a)
In the first first-level feat Stats, I’m interested in stimulus-induced activations. Totally 8 EVs were modelled. In the 3-column format for EV setup, I used onset time, onset duration, and intensity (all “1”). Then I performed a second-level analysis, setting a group mean contrast (“1”), and then I can get 8 mean group activation maps for each condition.
(b)
However, for the 2nd stimulus, I’m more interested in activations that correlated POSITIVELY and NEGATIVELY with the behaviour scores. So I run a second first-level analysis but, in the 3-column format of the 4 EVs in the 2nd stimulus, the third column (intensity) was replaced by the corresponding behaviour scores. Again I performed another second-level analysis, but this time I set two group mean contrasts “1” and “-1” to find the POSITIVE and NEGATIVE correlation areas for the 2nd stimulus, respectively.
My questions are:
(1).Did I do a correct job?
(2).Should I demean the behaviour scores?
(3). In (a) and (b), the 4 activation maps related to the 1st stimulus are slightly different. If I want to report activations correlated POSITIVELY and NEGATIVELY with the behaviour scores in the 2nd stimulus as well as those related to the 1st stimulus, should I report the 4 activation maps of the 1st stimulus in (a) or (b)?
Thanks in advance.
Mark
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