I don't think it's purely an intro- vs. extrovert thing: as an anecdote, I tend to test as introvert, but find what the sister comment says very much applicable: it is hard to impossible to focus and/or maintain motivation without "seeing other people do things". Perhaps this has something with the ADD<->OCD scale, which I am firmly at the left end of: generally, I do not get distracted by sounds/questions/etc and very easily go back to what I was doing before distraction; but at the same time I find it rather difficult to e.g. avoid going off on unnecessary tangents, which is where seeing other people work helps.