[amirmc]

The sibling comment is correct, in that you're always measuring differences. The 'baseline' isn't a canonical one but specific to your experimental design (and research question).

For example, if I were interested in which regions respond to pain and pleasure I have several ways I could design a study. I could have a 'pain' condition (drink something bitter), and a 'pleasure' condition (drink something sweet) and then just do comparisons between them (pain - pleasure, and the inverse). However, I could also include a 'neutral' condition (drink plain water) and now I can compare the emotional conditions against the 'neutral' one and extract the regions that are generally involved in emotion.

Also, your comment highlights another problem when research work is badly disseminated. The concept of logic is not being examined whatsoever, yet you've taken 'cognitively driven' (already a false statement) to mean 'logical'.