Thanks, @evergreen5 . That data shows a correlation between intellectual giftedness and introversion. I would suppose that the intellectually gifted would generally also be studious since that is the natural way of using their special gifts. The psychological and temperamental habit of studiousness would come secondarily. An interesting statistic would be one that correlated the gifted and the studious. I doubt that the correlation is absolute, but it must be very strong. The correlation must be somewhat less strong for those who are smart enough but not truly gifted. That group must divide between those who are temperamentally studious and those who study and learn only what they need to know for another end. I suppose I am suggesting that introversion tends to characterize the first part of this subdivided group, less so the second part.