Preventable medical mistakes frequently involve wrong-sided surgery: an injection to the wrong eye, for example, or a biopsy from the wrong breast.
These "never events" – serious and largely preventable patient safety accidents – highlight that, while most of us learn as children how to tell left from right, not everyone gets it right.
While for some people, telling left from right is as easy as telling up from down, a significant minority – around one in six people, according to a recent study – struggle with the distinction.
Even for those who believe they have no issues, distractions such as ambient noise, or having to answer unrelated questions, can get in the way of making the right choice.
But telling left from right is different, she says.
"It's because of the symmetry, and because when you turn around, it's the other way around, and that makes it so confusing.".
Left-right discrimination is actually quite a complex process, calling upon memory, language, visual and spatial processing, and mental rotation. »