Dear Cornelius,
> I know that the AR(1) among others are supposed to take care of high
> frequency noise. But let's suppose I have a block design (SOA 36
> seconds), and I have the strong suspicion that there is still much (hf)
> noise in my data - how could I invoke the low-pass filter in SPM2
> (preferably in batch mode)?
You have to be careful here, since a high frequent noise, having a higher frequency than your sampling rate of the data, which is very likely, will turn into a low frequent component in the signal (which is called 'aliasing')
So, it might be more suitable to adjust the high-pass filter, even it sounds not intuitive at its first glance.
Good luck,
Karsten
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Karsten Specht, PhD
Department of Biological and Medical Psychology
& National Competence Centre for functional MRI
University of Bergen
Jonas Lies vei 91
5009 Bergen
Norway
Tel.: +47-555-86279
Fax: +47-555-89872
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http://fmri.uib.no/
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