Common misconceptions
Some false beliefs are so widespread they feel like common knowledge. Here's a cheerful correction service for the greatest hits—all verifiable, all things “everybody knows.”
Your body
Myth
The claim: You only use 10% of your brain.
Actually: You use essentially all of it, across the whole day. There is no locked 90%.
Myth
The claim: You swallow 8 spiders a year in your sleep.
Actually: This is a famous fabricated 'fact' — ironically invented to demonstrate how easily fake facts spread. Spiders avoid sleeping humans; the number is made up.
Myth
The claim: Your tongue has separate zones for each taste.
Actually: The 'tongue map' is a misreading of old research. All taste regions detect all basic tastes.
Myth
The claim: Hair and fingernails keep growing after death.
Actually: They don't. The skin dehydrates and retracts, making them appear longer.
The natural world
Myth
The claim: Bats are blind.
Actually: Bats can see; many see quite well. They also use echolocation. 'Blind as a bat' is just wrong.
Myth
The claim: Bulls are enraged by the color red.
Actually: Bulls are red-green colorblind. They react to the cape's movement, not its color.
Myth
The claim: Lightning never strikes the same place twice.
Actually: It frequently does — tall structures like the Empire State Building are hit many times a year.
Myth
The claim: Dogs age 7 human years per year.
Actually: Aging isn't linear; dogs mature fast early then slow down, and it varies hugely by breed and size.
Everyday life
Myth
The claim: We only dream in black and white.
Actually: Most people dream in color. The myth may date from the black-and-white-television era.
Myth
The claim: Cracking your knuckles causes arthritis.
Actually: Long-term studies find no link. The pop is just gas bubbles in the joint fluid.
Myth
The claim: Sugar makes children hyperactive.
Actually: Controlled studies don't support it — the effect is largely in the expectations of the observing adults.
Misremembering as a group is a special case — see the Mandela effect. And for the newest source of confident nonsense, AI hallucinations.