The sky is blue because it reflects the sea and the sea is blue because it reflects the sky. You can suck the venom out of a snake wound if you react quickly enough. Those self-same reflexes will be useful so you can bop a shark on the nose when it tries to attack you. The Great Wall of China is the only man-made object you can see from space, unless you are as blind as a bat. Such vertical knowledge, or “everybody knows” knowledge, is ingrained in our everyday consciousness. Too bad none of it is true. It’s called the “illusory truth effect”, a mechanism whereby a person’s perception of truth is skewed towards an understanding that feels familiar. We tend to assess new information against what we already know to be true, so if we hear the same thing repeated with some authority we tend to just accept it. The phenomenon was first detailed in the study “Frequency and the Conference of Referential Validity” in 1977. Lynn Hasher, David Goldstein and Thomas Toppino asked a group of coll...

BL Premium

This article is reserved for our subscribers.

A subscription helps you enjoy the best of our business content every day along with benefits such as exclusive Financial Times articles, ProfileData financial data, and digital access to the Sunday Times and Times Select.

Already subscribed? Simply sign in below.

Questions or problems? Email or call 0860 52 52 00. Got a subscription voucher? Redeem it now