There are many of us who enjoy people-watching. One of life's pleasures is sitting in a coffee shop, watching the world go by, making up narratives about people we see. It's fascinating to imagine their relationships, to guess their careers and life choices. Perhaps we should call it people-judging. But we need to be able to make snap judgements, based on little information. It's only when we think that these impressions carry genuine weight, that we make mistakes. Don't judge a book by its cover.