Note also this related question that I asked and that had some good discussion:
https://www.lesswrong.com/posts/KFWA9dMFAnic56Zt3/how-good-is-a-human-s-gut-judgement-at-guessing-someone-s-iq
Note also this related question that I asked and that had some good discussion:
https://www.lesswrong.com/posts/KFWA9dMFAnic56Zt3/how-good-is-a-human-s-gut-judgement-at-guessing-someone-s-iq