Hi all,
I'm currently analysing data from an fMRI study, with subjects looking at visual stimuli with different valences.
In my first level analysis, I have EVs which represent individual trials and are currently weighted as 1.
However, I also have a behavioural measure that describes the subjects' performance per trial and would like to include this information and so have created EVs weighted by subjects' scores on this measure.
When designing the model for the first-level analysis, should I be including the performance naïve regressors (i.e. weighted 1) as well as the behaviourally scaled regressors and then compare them at this level, or should I run them as two separate analyses and then make a higher-level comparison? - to see whether the behaviourally scaled EVs are better at describing my data?
Also, is there anything I need to do to ensure my design is not rank deficient?
Any general hints or insights into interpretation would be much appreciated
Olivia
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