Psychologists brought in by teams will sift through a player's answers and try to decipher trends to help explain how he learns best (say, through written vs. verbal instructions) or is an introvert or extrovert.
Meanwhile the Guardian's Jon Ronson is bemused that after concluding his whole family are ambiverts - which Cain defines as a mixture of extrovert and introvert - the group barely gets a mention in the book.