Hi SPM'ers,
Setting up a first-level model, Im faced with the decision if to include time and dispersion parameters under the Canonical HRF model. Based off of the help, as well as the manual, I understand that these parameters give the HRF function some leeway in it's 'preciseness' - ie that it can happen a few second earlier or later and has a larger spread (dispersion).
Is this correct?
Thanks,
Joelle