What if the causation is the opposite? What if the people who ruminate more or are more anxious about conversations become smarter and more eloquent, by taking more time analyzing those things?
If we stick to IQ as the definition of 'cleverness' (which can be argued, of course), then this is not really true. IQ cannot be significantly increased with learning, conversation, etc. I used to be* a Mensa member, and it's really surprising and eye opening to see the variety of people there. You can find university teachers and enterpreneurs, but they are not too common. The average Mensa member is really an average citizen with an average job - librarian in a small town, sysadmin in an elementary school, or just an unemployed, depressed twenty-something.
*: you need to pay membership fee to be a member, and I found it really uninteresting after a while to go to Mensa meetings. IQ is not something that can really connect people.
