What each is said to mean — and what is actually going on.
Tradition. Money coming in — in most of Europe and North America. In parts of India and the Caribbean the sides are reversed.
Actually. Dry skin, eczema or contact irritation. Persistent itching without visible cause is worth mentioning to a doctor.
Tradition. Money going out. The mirror of the right, and equally regional.
Actually. Same as the right. Palms itch because skin is skin.
Tradition. Someone is talking about you — right ear praise, left ear criticism. Recorded by Pliny in the first century.
Actually. Tinnitus. Common, usually benign, but sudden onset in one ear warrants medical attention.
Tradition. Varies wildly by culture — good news, bad news, or a visitor, depending where you are.
Actually. Myokymia, almost always caused by fatigue, caffeine or stress. It resolves on its own.
Tradition. Someone thinking of you. The blessing after a sneeze survives from a belief that the soul briefly left the body.
Actually. Irritation of the nasal lining. The soul is fine.
Tradition. Someone is talking about you, and they will stop when you name the right person.
Actually. Diaphragm spasm. Hiccups lasting over 48 hours are considered persistent and should be looked at.
Tradition. Bad luck in Britain and North America; good luck in Japan, Scotland and much of continental Europe. The split traces to medieval witch panic in some regions and not others.
Actually. A cat crossed the road. Black cats are adopted from shelters at measurably lower rates because of this belief, which is the only real harm it causes.
Tradition. Seven years of bad luck — Roman in origin, from the belief that mirrors held a piece of the soul and life renewed on a seven-year cycle.
Actually. Mirrors were extremely expensive until the nineteenth century. A superstition that made servants careful with them had obvious utility.
Tradition. Bad luck, averted by throwing a pinch over the left shoulder into the devil's face.
Actually. Salt was a currency — the word "salary" comes from it. Wasting it was genuinely costly.
Itching, ringing and twitching are involuntary, noticeable and have no obvious cause — exactly the conditions under which people generate explanations. Almost every culture has readings for them, and the readings often contradict each other across a single border, which tells you what they are worth as predictions.
What is striking is how many map onto money and gossip: the two things people most want advance warning about.