A reader writes:

In regards to your post on Types, I would note that in cognitive psychology they found we remember people by a caricature (an exaggeration of their unique features).  That's why it's so easy to recognize a friend or a celebrity based on a caricature.  I think this theory holds that different entities are remembered most by their divergence from the norm rather than their average characteristics. This probably relates to humor, which is based on caricatures.  We laugh because the caricature while not an accurate representation sounds more true than truth.

Thus, once you see Malvina Hoffman's sculpture of a 6'-8" Nuer tribesman, it's easier to remember what Nuers look like when you read about the recent plebiscite in the Sudan. Of course, many contemporary academic trends, such as changing the names of ethnic groups every few years, is intended to do the opposite: lessen knowledge.