When you watch this multimedia exhibit video…you’ll see Dr Gustav Kuhn performing a vanishing ball trick. Can you work out where the ball went?
We often tend to look where another person is looking and magicians take advantage of this by turning their head or focussing their eyes away from where they’re performing a sleight of hand.
When you’re next talking to someone and you see them look over your shoulder, see if you can resist the urge to turn around to look where they’re looking!
This exhibit’s video was donated by Dr Gustav Kuhn and Dr Michael F. Land.
This exhibit shows how magicians sometimes manipulate our social habits and expectations when they perform ‘magic’ tricks to fool an audience.
When you watch this video, you’ll see Gustav throwing a ball into the air and catching it. Then suddenly on the third throw, the ball seems to disappear in mid-air…the vanishing ball illusion!
On the third (dummy) throw, Gustav pretended to throw the ball, by motioning his hand upwards, while moving his eyes and head as though he was watching the ball fly up into the air. In reality, he kept hold of the ball in his hand.
In an experiment, about 68% of people perceived that the ball left Gustav’s hand during the ‘dummy’ throw and that the ball disappeared off screen at the top—even though the ball stayed in his hand.
These people had their eyes tracked while watching the video, and it revealed that they looked at Gustav’s social cues (head and eye movements) before they looked at where the ball was meant to be at the top of the screen.
This suggests that people’s oculomotor control system (i.e. eye movements and bottom up visual processing) was not fooled by the illusion, but their perception was fooled into thinking that the ball had been thrown up into the air.