Dave Munger of Cognitive Daily writes High IQ: Not as good for you as you thought, in which he discusses research that looked at IQ and "self discipline" as predictors for academic performance. The surprise? Self-discipline was more highly correlated than was IQ.
Both IQ and self-discipline are correlated with GPA, but self-discipline is a much more important contributor: those with low self-discipline have substantially lower grades than those with low IQs, and high-discipline students have much better grades than high-IQ students. Even after adjusting for the student’s grades during the first marking period of the year, students with higher self-discipline still had higher grades at the end of the year. The same could not be said for IQ. Further, the study found no correlation between IQ and self-discipline — these two traits varied independently.
As Munger says, there is much more to be studied, but this is an interesting result, as possibly why I am interested in the general idea of "personal effectiveness" as relates to focusing on a task and getting my stuff done. Anecdotally, I find that I do my best work when I do one thing and move to the next, rather than jumping around willy-nilly. And I see the same thing in others. For those that missed it last year, here is an entertaining video about Getting My Stuff Done that I think of when I find myself free-associating, instead of working.