I don't have a way to easily test an external regressor. There are a couple of ways to do this type of analysis though. You can use a 4 column paraidgm file and code the weight (4th col) as the reaction time. This will weight the HRF for each presentation by its RT. Alternatively, you can recode your stimuli by binning them based on the RT range they fall into.

doug

On Tue, 19 Feb 2008, Zhen Zonglei wrote:

Dear FS and fsfast expert:

We want to know the effect of some external regressors such as the reaction time of every trial. We found that external regressor can be integrated into the GLM model with mkanalysis-sess's 'extreg' option, but we did not find the way to do comparison of these external regressors and see the effects of them.Do you know how to do it with fsfast?

Thanks in advance for any help!

Zonglei Zhen