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kottke.org posts about bodies

How to tell left from right

posted by Tim Carmody   Jun 16, 2016

Not everyone can distinguish between left and right. Besides natural affinity (or lack of it), health, drug use, other chemical changes, and stress can all cause our basic body compass to break down.

Telling left from right necessitates complex brain processes that include spatial perceptions, memory, language, and the integration of sensory information. The task is made increasingly complex when a person must identify laterality on someone else. Yoga teachers and other fitness instructors have it extra rough: While calling out to students to bend their left knee, the instructor has to raise their own right to mirror the class…

However, the field under the most pressure to avoid lateral confusion is medicine. In the dentist’s chair, there’s money wasted when hygienists x-ray the wrong tooth. It’s even worse when a left-right-disoriented dentist pulls one or more teeth from the incorrect side of the mouth. It’s even more serious in general surgery: A 2011 report estimates that there are 40 wrong-site surgeries done weekly in the U.S., and many of those involve mixing up a patient’s left and right. This is a devastating problem: If a doctor removes the healthy kidney and not the cancerous one, the results can be fatal. Wrong eye? Now we have a fully blind patient.

There’s nothing inherent about left, right, up, and down — or what are sometimes called “egocentric coordinates.” Speakers of Guugu Yimithirr in Australia famously use a coordinate system that leans much more heavily on absolute geocentric references at right angles (their equivalent of north, south, east, and west).

This plays a little easier when you’re playing off objects with fixed positions, like landmarks, or especially, the sun, than it does in big twisty-turny cities. But you could imagine in a world with ubiquitous handheld maps and compasses that a north/south/east/west orientation might make more sense.

What’s more, some of the old tech people used to train themselves to distinguish or remember left and right — miming handwriting, or wearing a wristwatch on one arm — aren’t as common or dominant as they once were. See also: distinguishing angular position by analogy with the face of an analog clock.

Either we come up with new tricks and new metaphors, or it’s conceivable that what’s seemed like an intuitive, natural way to think about the relative position of bodies in space could become a whole lot less intuitive for more and more people.