Hello,
I have a 2X2 factorial design and therefore 4 possible experimental
conditions. Each subject did two experimental runs such that in run 1 I only
have conditions 1 and 2, and in run 2 I only have conditions 3 and 4.
I was thinking about defining my factors at the first level analysis, but
when attempting to estimate the model I get an error because there are only
two conditions per run and SPM is looking for 4.
I though that I need to concatenate the time series of both experimental
runs in a single session within the model definition so that I can define
the four conditions for this single session. I think that just adding the
extra files to the scans is not a good idea, as concatenation of time-series
is not so direct.
Could you please tell me what would be the proper way to do this
concatenation. Do I need to add an extra regressor? Is there any matlab
function I need to run in my time series before?
Thanks for your help,
Javier.
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