You’re Not the Only One Who Doesn’t Know Right From Left

Arrows on road signs pointing in different directions, close-up
Photo: David Samuel Robbins/Getty Images

Some people, when asked to raise their left hand, immediately and confidently know which hand is which. And others (like me) must make a surreptitious L-shape with both thumbs and forefingers to see which one makes the forward-facing L before, not so confidently, raising the correct hand

Scientists aren’t exactly sure what causes some people to mix up their left and right, but studies have suggested that it’s not uncommon — around 20 percent of the population may struggle with this, according to some estimates. (Thanks to BuzzFeed for digging up that research and making me feel a little less alone, by the way.) But some new research suggests that simply being distracted is enough to make people worse at telling left from right. 

In most contexts, it’s a problem that’s slightly embarrassing at worst, but in the operating room, confusing left and right can lead to some dire consequences, writes Gerard Gormley, a researcher at Queen’s University Belfast who has studied left-right confusion among med students. What if you go in for a surgery on your left knee, and the surgeon operates on your right, for example? It’s a version of a medical error called wrong-site surgery, and it happens in about one in every 112,994 surgeries.

Gormley writes about his latest research on the subject, published this month in Medical Education, in a recent post for the Conversation:

While objectively measuring 234 medical students’ ability to distinguish right from left, we subjected them to the typical ambient noise of a ward environment and interrupted them with clinical questions. … Even the background noise of a ward environment was enough to throw some medical students off when making right-left judgments. Asking them a series of questions while they were trying to distinguish right from left had an even greater impact. The “distraction effect” was greater for older and female students.

He also writes that in his work on the subject — and it’s not his first time studying the issue — he’s found that just because students think they’re good at telling their left from their right does not always mean they actually are. (If you’re curious about your own skills, you can test yourself against others here.) Gormley’s work has found that some people with left-right confusion are also sometimes confused by their own L-shape hand trick. Spatial reasoning clearly doesn’t come naturally to everyone

One Reason You Can’t Tell Your Left From Right