Dear AFNI experts,

I have a question regarding the modelling of multiple events at the same time using amplitude modulated regression. We ran a reinforcement learning paradigm where we generated trial-by-trial estimates of expected value (EV), prediction error (PE) and learning rate (LR). We always model PE and LR at exactly the same time (and both have exactly the same duration - 1 second), but, importantly, the amplitudes are uncorrelated. When we try to run the model, AFNI gives us a collinearity error (see below). Is there any way around this? I found a handout online which stated the following: “Future directions: Allow more than one amplitude to be married to each stimulus time (insert obligatory polygamy/polyandry joke here) – this is done now” - this makes me think it SHOULD be possible.

Thanks,

Dennis Hernaus

*+ WARNING: -------------------------------------------------

*+ WARNING: Problems with the X matrix columns, listed below:

*+ WARNING: !! * Columns 16 [PE#0] and 18 [LR#0] are (nearly?) collinear!

*+ WARNING: -------------------------------------------------

*+ WARNING: !! in Signal+Baseline matrix:

- Largest singular value=1.93535
- 1 singular value is less than cutoff=1.93535e-07
- Implies strong collinearity in the matrix columns!

*+ WARNING: !! in Signal-only matrix: - Largest singular value=1.56269
- 1 singular value is less than cutoff=1.56269e-07
- Implies strong collinearity in the matrix columns!

*+ WARNING: +++++ !! Matrix inverse average error = 0.00255102 ** BEWARE **

** ERROR: !! 3dDeconvolve: Can’t run past 4 matrix warnings without ‘-GOFORIT 4’

** ERROR: !! Currently at -GOFORIT 0

** ERROR: !! See file 3dDeconvolve.err for all WARNING and ERROR messages !!

** ERROR: !! Be sure you understand what you are doing before using -GOFORIT !!

** ERROR: !! If in doubt, consult with someone or with the AFNI message board !!

** FATAL ERROR: !! 3dDeconvolve (regretfully) shuts itself down !!