Thinking about a previous discussion on the list, we said that
reaction time effects are better captured by a variable epoch
durations, which adapts to reaction time length.
In a couple of papers was shown that a variable epoch aproach is
better than parametric modulations.
But isn't this the same as adding a dispersion derivative, which would
convolve a longer HRF automatically for RTs and capture that signal
the same way as a variable epoch approach?