Dear Andreas,
> here is my latest heartbreaker: I want to transpose an EKP-paradigm
> into the scanner. Currently, it runs with an SOA==2s, ISI==1.5s on 192
> events of looking at visual objects and 22 events of reading sentences
> (SOA==3s, ISI==1.5s) which are to focus attention by obedience. Visual
> objects consist of 4 faces (2 male, 2 female) each expressing
> happiness, sadness and no particular emotion (==3 "emotions") eight
> times (i.e. 96 facial recognition task events). At 96 occasions
> (events), the individual has to recognize visual objects which aren=B4t
> faces but buildings. Does this per se sound like a sensible
> efMRI-paradigm? What would people suggest to build a reasonably
> powerful design matrix? I have noticed that SPM99 features to suggest a
> matrix for a paradigm but I do not know how to persuade it...
It sounds like a very reasonable design that would translate easily
into fMRI. I would use a rapid stochastic design (that could be
specified automatically before acquiring the data in 'fMRI models').
There would be e.g. 7 trial types (sentences plus three emotions x two
tasks) depending on your design, plus null events. Here the SOA would
be 2 seconds for all event-types. Note that you can averge over trials
for main effect (e.g. happy vs. sad) with the appropriate contrasts.
I hope this helps - Karl
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