I'm planning an event-related fMRI-experiment to investigate the difference in processing natural and computer-generated expressions. For this, we recorded videos of 4 different actors posing fearful and neutral expressions which last 3 seconds each and will compare them to computer-generated videos of fearful and neutral expressions. This was planned as 4 different conditions.
We noted now that the videos/expressions we recorded are of different emotional intensity (preliminary subjective ratings). Meaning some natural fearful expressions seem to be less emotionally intense than other natural fearful expressions and some artifical fearful expressions seem to be less emotionally intense than other artificial expressions. In general, artificial fearful expressions seem to be less emotionally intense than natural fearful expressions.
If we run the fMRI experiment as planned and contrast for example BOLD response to natural fearful expressions with BOLD response to artificial fearful expressions, how would the different emotional intensities of the videos affect the results?
We do not have enough videos to form a further "emotional intensity condition" and model the influence of the emotional intensity ratings in subsequent analyses.