> we presented participants with tests that assessed their ability in a domain in which knowledge, wisdom, or savvy was crucial: humor (Study 1), logical reasoning (Studies 2-and 4), and English grammar (Study 3).
They picked humor because they think it reflects "competence in a domain that requires sophisticated knowledge and wisdom". They then realized the obvious objection - it's subjective - and decided to do the logical reasoning task to try and rebut those complaints (but then why do the first experiment at all?):
> We conducted Study 2 with three goals in mind. First, we wanted to replicate the results of Study 1 in a different domain, one focusing on intellectual rather than social abilities. We chose logical reasoning, a skill central to the academic careers of the participants we tested and a skill that is called on frequently ... it may have been the tendency to define humor idiosyncratically, and in ways favorable to one's tastes and sensibilities, that produced the miscalibration we observed-not the tendency of the incompetent to miss their own failings. By examining logical reasoning skills, we could circumvent this problem by presenting students with questions for which there is a definitive right answer.
So logical reasoning was chosen because:
1. It's objective.
2. It's an important skill.
3. It's a general "intellectual" skill.
That makes it very important if it's actually a good test of logical reasoning. If it was truly an arbitrary test like an egg-and-spoon-race or something, then there's no reason to believe the results would generalize to other areas of life and nobody would care.