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2014 The Bad Science Show - Melbourne School Shows & School Incursions

Change Blindness
Deceptology - The Neuroscience Of Deception

“After all, the true seeing is within.” 

*This resource is intended for use after viewing Deceptology. If you've haven't seen the show, this won't make much sense.


To explain the limitations of the human eye and how the brain makes up for these short comings. 


The Trick

In Deceptology, I threw a ball in the air that appeared to vanish in mid-air. Not matter how closely the audience followed the ball's path, they just could keep up with where the ball was or even how many balls were there.


The Explanation

There are several ways to vanish a small object like a ball. It is easier to start with a coin when practicing. Hold the coin in the palm of your right hand. Reach over with your left hand and pretend to take the coin. Drop your right hand by your side as your left hand moves away.

Keep your eye on the imaginary coin as you pretend to throw it in the air. You can then reach into your pocket with right hand and "find" the coin.  

So why do we see the coin vanish in midair when it never left my right hand?

Because of 'prediction errors'

Because it takes time for our brain to process There is delay between an event happening and us experiencing it.

That delay can be us short as 13ms and as long as 15 seconds. So your brain makes up for this delay by guessing when an object should be, rather than where it is.

You've heard of living in the present, predicting in the future. Well your brain is living in the past trying to predict the present.

Psychologist Gustav Kuhn found that 1 in 3 people experience the ball vanishing in mid air. This number was even higher when he really threw the ball in the air first to teach the participants brain what to expect.

Have you ever pretended to throw a chip for a seagull only to have it chase after the imaginary food? Your brain is doing the same thing, trying to predict the path of an object that isn't there.

Gustav Kuhn's original test video also doubles as german expressionist art.


My career as a hitchhiker was hampered by the fact that I never left my lounge room.

Also, I look like a serial killer.


Further Reading

Backyard Brains - How Your Eye Detects Colour and Motion

Scientific American - Put Your Vision To The Test

The Card To Pocket Instructions

Nicholas J. Johnson


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