Yes, you're correct. For each condition there will be a column for
each basis function. If you specify just a canonical HRF, there is
just one --- hence bf(1). If you had specified the HRF and a temporal
derivative, you would then have two columns for each condition: one
for the HRF noted bf(1), and one for the temporal derivative noted
You can't tell from bf(1) that it is the canonical HRF; you have to
see what you selected when specifying your model. However the
canonical HRF with no derivatives is the most common choice, so if you
only have one basis function (as in your example), it's likely to be
Hope this helps,
On Mon, Jan 12, 2009 at 2:57 PM, Yune S. Lee <[log in to unmask]> wrote:
> Dear SPM experts,
> I'm wondering what bf(1) for that is at the end of each name in SPM.xX.name.
> For instance, if I look at SPM.xX.name, I can view all the regressors that I
> made as belows.
> ans =
> Columns 1 through 7
> 'Sn(1) bd1*bf(1)' 'Sn(1) bd2*bf(1)' 'Sn(1) bd3*bf(1)' 'Sn(1) bd5*bf(1)'
> 'Sn(1) bd6*bf(1)' 'Sn(1) bd7*bf(1)' 'Sn(1) bd9*bf(1)'...
> I thinkg the first Sn(1) refers to each run and the second bd1 is the
> condition name that I made, but I wasn't sure what bf(1) means at the end.
> Assume it is one of the hrf that is convolved with the onset time of the
> condition. But, I'm not exactly sure what it is.
> Any help would be appreciated.