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Copycat? Sleight-of-hand magic trick only fools monkeys with opposable thumbs, study finds
- Deceptive tricks only fool monkeys that have opposable thumbs
- A magician must have a similar anatomy to his audience
When performing magic tricks, it is important to choose your audience carefully.
And according to a new study, it would be wise not to try sleight of hand with a group of marmosets.
Researchers have discovered deceptive tricks that only fool monkeys with opposable thumbs, since a magician must have a similar anatomy to his audience.
So while capuchins and squirrel monkeys are tricked by “tricky hands,” species without an opposable thumb aren’t so easily fooled, their research suggests.
Psychologists at the University of Cambridge performed a famous magic trick for three types of monkeys with different hand structures.
A Humboldt squirrel monkey is tricked by the French Drop’s sleight of hand magic trick as part of the experiment
They used a sleight of hand called the French drop in which an object appears to disappear when an onlooker assumes it was taken from one hand by the hidden thumb of the other hand.
The trick—often the first a budding magician wants to master—involves holding a coin with two fingers of one hand.
The other hand extends, palm facing the magician with the thumb hidden behind their fingers.
The public knows the thumb is lurking, ready to grab, so assumed the coin has been grabbed when the hands part and it is no longer visible.
Their attention follows the seconds hand, only to find it empty at the ‘reveal’. The magician has secretly dropped the coin into the palm of the original hand.
The researchers performed the trick on 24 monkeys, including capuchins and marmosets, both of which have opposite thumbs but with different dexterity, and marmosets, which do not have opposite thumbs.
The trick – often the first a budding magician will want to master – involves holding a coin with two fingers of one hand
The other hand extends, palm facing the magician with the thumb hidden behind their fingers
The public knows the thumb is lurking, ready to grab, so assumed the coin is grabbed when the hands part and it is no longer visible
Their attention follows the seconds hand, only to find it empty at the ‘reveal’. The magician has secretly dropped the coin into the palm of the original hand
Food chunks replaced coins and were given as a reward – but only if the animals guessed correctly.
Analysis revealed that monkeys with opposable thumbs were fooled more than 80 percent of the time—much like the human audience—by assuming the hidden thumb had grabbed the treat and choosing the wrong hand.
Meanwhile, the monkeys without opposable thumbs were fooled just 6 percent of the time.
Dr. Elias Garcia-Pelegrin, one of the study’s authors, said: ‘Magicians use elaborate techniques to trick the observer into experiencing the impossible.
“By examining how primate species experience magic, we can understand more about the evolutionary roots of cognitive deficits that expose us to the cunning of magicians.”
Writing in the journal Current Biology, the team writes that their research suggests that sharing a biomechanical ability may be necessary to accurately anticipate the movements of those same limbs in other individuals.
Senior author Professor Nicola Clayton said: ‘There is increasing evidence that the same parts of the nervous system that are used when we perform an action are also activated when we watch others perform that action.
“This mirroring in our neural motor system could explain why the French drop worked for the capuchins and squirrel monkeys, but not for marmosets.”