[log in to unmask] wrote:
> Dear Will,
> How are you?
> I have a question regarding how to do conjunction analysis on the
> second level. Hope you can help me out. thanks!
> I had one group subjects who performed 3 tasks (A,B and C). In each
> task, they had 2 conditions (C and I) for both uncrossed (u) or
> crossed (c) hands, so totally four conditions which were uC, uI,
> cC,cI in each task and it was a 3*2*2 factorial design. In the first
> level, I have specified the contrasts, such as uI-uC, cI-cC,
> (uI+cI)-(uC+cC) and (cC+cI)-(uC+uI) for each task. Now I want to do
> conjunction analysis in the second level,e.g where is the common
> activation of uI-uC for the three tasks? When I clicked on the second
> level, which one I should select, full factorial or flexible
> factorial design? I guess I don't need to use one-sample or
> two-sample design. Thanks!
For each subject generate three contrasts. These will
be uI-uC for each of the three conditions.
At the second level select a full factorial design. Then create
a single factor with three levels. Your design will be a one-way ANOVA
with three levels. You'll have three columns in your design matrix - one
for each condition.
After estimating the model parameters, select the three contrasts
(select multiple contrasts by
pressing the control button - or is it shift, shift/control I forget)
[1 0 0], [0 1 0] and [0 0 1].
William D. Penny
Wellcome Trust Centre for Neuroimaging
University College London
12 Queen Square
London WC1N 3BG
Tel: 020 7833 7475
FAX: 020 7813 1420
Email: [log in to unmask]