TEN WAYS TO WIN WITH MAGIC AND ILLUSION
AMAZING FACTS ABOUT VISION
• Vision is our most dominant sense, with about 30 per cent of the neurons in your brain being devoted to seeing, compared to just 8 per cent for touch and 2 per cent for hearing.
• The image on the back of your eye is actually upside down, but your brain turns it around and allows you to see the world the right way up.
• Each of your eyes has a blind spot where the optic nerve attaches, but you don’t notice the holes because your brain fills in each eye’s blind spot with its best guess.
• Your eyes can detect more than 10 million colours but only about thirty shades of grey.
• Babies are hardwired to prefer to look at faces and are especially attracted to anything that looks like eyes.
LINE THEM UP
Show this picture to your friend and tell them that the horizontal lines are straight. When they don’t believe you, use a ruler to prove that you’re right.
This illusion was first reported by psychologist Professor Richard Gregory in 1979. Gregory was studying visual perception in Bristol, and a member of his team saw the illusion in the tiling on the wall of a local cafe. Ever since then it has been referred to as the ‘cafe wall’ illusion.
THE QUEEN IS AMUSED
Tell your friend that you can make the portrait on a banknote smile. When they accept the bet, take any banknote with a portrait on it (try a ten-pound note*) and fold the note over along the middle of the person’s nose. Next, put a second crease, in the opposite direction, through each of the portrait’s eyes, so that you end up with a zigzag banknote.
When you tip the note away from you the person in the portrait will smile, and when you tip it towards you they will frown.
THE HAT-TRICK
Place a coin on a table heads up and cover it with a hat. Tell your friend that you can make the coin turn over, but without touching the hat. Next, click your fingers and announce that the coin has flipped over. When your friend picks up the hat to see if you are right, quickly reach forward and turn the coin over. You have won the bet!
GOING DOTTY
Show your friend this page and ask them to count the black dots. They will be there forever!
This weird effect was first discovered around the turn of the last century, and for years textbooks attributed the illusion to a strange quirk of the retina known as ‘lateral inhibition’. The bad news is that this explanation is very complicated. The much better news is that we don’t have to concern ourselves with the explanation because it was recently shown to be complete nonsense. Some researchers now believe that the illusion is due to ‘S1 type simple cells’ in the retina, but give it a couple of years and that will probably be shown to be wrong too. Quite frankly, no one really knows what’s going on. If you have any good ideas, jot them down on a postcard, mark it, ‘Solution to grid illusion: you know, the one where you see the dots in the gaps’, and send it to your nearest psychology department.
THE MISSING PIECE
Cut a rectangular piece of paper into five parts like this.
Reassemble them in front of your friend, and announce that you will assemble the rectangle again, but this time one part of it will magically disappear. When your friend accepts the bet, just exchange the two triangles, put the other pieces back like this, and now one square has vanished.
Actually, the second rectangle isn’t perfect. Instead, there are several irregularities which, when they are all added up, account for the missing square.
A TALL DRINK
Bet your friend that the circumference of a pint glass is actually twice the height of the glass. When they don’t believe you, use a piece of string or a napkin to show that you are right.
This bet works, in part, because we all have a tendency to overestimate the length of vertical things and underestimate the length of horizontal things. The width of the glass is horizontal and the height is vertical, and so we tend to think that it is narrower and taller than it actually is. The illusion does, however, have an upside. Researchers filmed people walking up some steps. Some of the time the front of the steps had horizontal lines painted on them, and some of the time they had vertical lines. The vertical lines made people overestimate the height of a step, which meant that they were less likely to trip over it.
FIND THE QUEEN
This bet involves a paper clip and five playing cards. One of the playing cards should be a queen. Place the queen in the middle position and spread the playing cards out. Show the playing cards to your friend, then turn your hand over and ask your friend to place the paper clip on the queen.
The way you’re holding the cards means that they will clip the paperclip around all of them and, because the back of the queen lines up with the face of the front card, when you turn the playing cards back around they’ll see that they have placed the paper clip on the front playing card, and you will win the bet.
THE EYES HAVE IT
Show your friend this page and ask them to read the sentence in the box.
Quirkology, the YouTube channel that plays with with your mind.
They will probably say ‘Quirkology, the YouTube channel that plays with your mind’. In fact, the box contains a repetition of the word ‘with’.
Your brain would have to be the size of a planet to be able to make sense of the constant stream of stuff that it receives from your eyes. Instead, without you knowing it, your brain cuts corners by relying on your past experience to double-guess what’s going on around you. For instance, if you see just three legs of a chair, you instantly assume that there is a fourth leg that you can’t see, because almost all of the chairs you have seen in the past have four legs. Most of the time your brain is right to make these shortcuts and everything is hunky-dory. However, once in a while you come across something that you rarely see – such as a sentence with two ‘with’s – and suddenly you fail to to see what is right in front of your eyes.
MIND GAMES
Tell your friend that you can make them say the word seven.
Then say, ‘What’s two plus two?’
They will reply ‘four’.
Then ask, ‘What’s three plus three?’
They will say ‘six’, and then you reply: ‘I won the bet, because you said six.’
They will answer, ‘But you said you would make me say seven.’
And then you really have won the bet.
BOTTOMS UP
Half fill two champagne glasses.
Now tell your friend that all of the liquid from one glass will fit into the other. The shape of the champagne glasses creates an optical illusion, and the glasses look as if they contain loads of liquid. When your friend accepts the bet, just pour the liquid from one glass into the other and you win the bet.
