Dear Experts,
In an event related fMRI emotion regulation paradigm, participants are asked to either passively view emotional images (positive, negative, neutral), or reappraise their feelings related to these images. These images are presented for 10seconds (in both View and Reappraise conditions).
Question of interest: “is there significant difference between Viewing and Reappraising emotional images”
I checked some reappraisal fMRI papers which were published last year, and most papers generally use the same duration for viewing and regulating during their first level analyses (although the duration between studies varies between 4-8 seconds).
There is some evidence suggesting that passively viewing these images is related to a short initial (amygdala) response, which rather quickly habituates. There is also evidence suggesting that the reappraisal process lasts for about 5 seconds.
Given these previous studies I was wondering if it would make sense to use different durations for the View and Reappraise conditions during my first level analysis. Specifically, I would model the View conditions with a stick function (duration = 0 sec) and my reappraise condition with a duration of 5 seconds. I would then compare these conditions in a second level analysis.
Is there any (theoretical) reason why it is flawed to compare events with such different durations?
Many thanks in advance!
Jochem
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