People, especially people who are most interested in material culture, often find it hard to accept that ancient art does not directly and literally depict the world. People who recreate Roman material culture, for example, often fret that when we can check it against other evidence, Trajan’s column is usually wrong. “But the rest of the sculpture is so lifelike,” they complain. “Shouldn’t we use what evidence we have?” “Why would they go to so much trouble to depict something wrong?”
One parallel which they might want to think about is the role of sound in movies and television. In the age of sound stages, digital libraries of effects, and sophisticated editing software, directors have almost total control over the sound track of their films. In theory, they could give each scene exactly the sounds which a bystander would hear in real life. In practice, film-makers adopt a set of stylized conventions which audiences learn to recognize. In the movies every symphony is Beethoven’s Fifth, every operetta “The Marriage of Figaro,” every jungle echoes with the calls of Australian frogs and Brazilian birds, every shotgun makes loud pumping noises when it is readied and a rather dull “BOOM” when it is fired, every sword leaves its scabbard with a “schling!” and foreign languages are replaced with whatever the local extras speak and the expected audience does not. Some of these sounds exist but have become stereotyped, some exist but not in the context in which they appear, some are jumbles of real things which don’t appear together in real life, and some are pure confections for the screen.
There are good reasons for this symbolism: using conventional sounds is easier for the film-maker, and easier for the film-goer. If the purpose of a sound is to communicate “this character is cultured” or “the thug with the shotgun is serious,” then the sound is right if most listeners will get the message, not if it is what one would really hear in that situation. Once a symbol has become recognized, it tends to persist even if the outside world changes. People whose closest contact with swords or jungles is on the screen may even mistake the symbol for the reality and complain when it is missing.
The best way to avoid being mislead by television and film is to seek knowledge of a domain and use that to test the fiction rather than vice versa. In material culture, we can start with archaeology and inventories, or study how other artisans with hand tools and natural materials made things, before we turn to the art. While this will sometimes cause us to reject something which is accurately depicted in art (a false negative), it is safer than relying on art alone for something which it was never meant to do.
Further Reading: Readers with lots of time on their hands should find plenty of leads on tvtropes.org; Bishop and Coulston’s Roman Military Equipment (currently in its second edition with talk of a third) is a good introduction to the various types of evidence for the equipment of the best-studied army in the ancient world.
s/naturalistic/lifelike to better reflect how most people talk, added link to Bishop and Coulston.