10 Mind Melting Illusions (And Exactly How They Work)

5. Tactile Illusion

We've had visual illusions, we have audio illusions, now this is a tactile illusion.

This trick had a renaissance in my primary school (it was the countryside, there's not much to do). You need two people, one closes their eyes, and one slowly moves their finger from their wrist to their elbow. The first person tells the second to stop when they think they've reached it and they will almost always pull them up short, convinced that the person's finger is right in the crook of their arm.

It is thought that the anticipation of the finger reaching the elbow causes the brain to believe it has. Combined with the slow motion of the finger dragging up the forearm, which is moving much more slowly than most of the things that we experience in day-to-day life, the brain just assumes that the finger has reached the elbow faster than it has.

As sensitive as our skin is, it's actually quite difficult to tell the exact position of a sensation on parts of the body that aren't the super-sensitive fingertips, so your brain, you guess it, takes a stab in the dark. This is supported by the observation that men are much easier to fool than women with this trick, due to their more sensitive skin.