I’m trying to use trial-by-trial behavior as a parametric/amplitude modulator and look at contrasts where I compare the modulation effects between conditions.
I saw the following post: https://afni.nimh.nih.gov/afni/community/board/read.php?1,78640,78703#msg-78703 which suggests that I should be doing the following:
-gltsym ‘SYM: myCondition1 -myCondition2’
I just want to double check that I am conceptually understanding this correctly. If I were to do the following:
-gltsym ‘SYM: +Ant.Mean -Ant.Nice’ -glt_label 3 Ant.Mean.V.Nice
it would be equivalent to: -gltsym ‘SYM: +Ant.Mean -Ant.Nice’ -glt_label 3 Ant.Mean.V.Nice
and would NOT be actually capturing any of the amplitude modulation?
Whereas the following: -gltsym ‘SYM: +Ant.Mean -Ant.Nice’ -glt_label 3 Ant.Mean.V.Nice
Would be examining the difference in the modulation effect between the Mean and Nice conditions