A famous trick deceives humans and primates with only opposable thumbs

When creating the famous focus Using three kinds of monkeys with different arms, scientists have found that in order to deceive, a magician needs an anatomy similar to that of his audience.

psychologists University of Cambridge (UK) they used trick called french drop, in which the object appears to disappear when the viewer assumes it has been removed from one hand by the hidden thumb of the other. They report their findings to Current biology.

Research conducted at the Comparative Cognition Laboratory Cambridge universitydiscovered that monkey who did not have opposable thumbs they did not succumb to the guess, as they were aware of the location of the delicious treats that the wizard was trying to make disappear.

Research suggests that the exchange of biomechanical abilities may be necessary to accurately predict the movements of the same limbs in other people. This is true even when these seemingly accurate predictions end up being confusing. illusionist hands.

“Magicians use sophisticated techniques to deceive the observer into experiencing the impossible. This is a great way to explore the blind spots of attention and perception,” explains Dr. Elias Garcia-Pelegrin, who has been doing magic for ten years and did experimental work during his PhD at Cambridge: “By examining how primate species experience magic, we can better understand evolutionary roots of cognitive deficiencies that leave us open to the cunning of sorcerers.”

“In this case, the ability to manually perform an action, such as holding an object between the index finger and thumb, is needed to predict the effect of that action on others,” adds Garcia-Pelegrin, a newly appointed associate professor at the National University. Singapore.

French fall trick: which monkeys won’t fall?

french drop this is usually the first trick anyone magician the chick seeks to dominate. The coin is shown in one hand. The other hand takes. The palm of the second hand is turned inward, the thumb magician hidden behind fingers

The audience knows that the thumb is ready to grab, so they assume they have caught the coin when it is no longer visible. His attention follows the second hand, only to find it empty when “opened up”. He magician he secretly dropped the coin into the palm of the original hand.

For monkey, pieces of food replaced coins and were given as a reward, but only if the animals guessed the correct hand. The scientists predicted that monkeys with opposable thumbs would behave like a human audience: they would think that the hidden thumb had caught the object, and they would pick the wrong hand.

They’ve done the stunt multiple times at 24. monkey: eight capuchins with peanuts, eight squirrel monkeys with dried mealworms and eight monkeys with marshmallows.

Capuchins are renowned for their agility, using stone tools to crack nuts in the wild. They can move each finger and have opposing thumbs that provide a “fine grip” between the thumb and forefinger.

Capuchins were regularly scammed by French gout (81% of the time). More often than not, they chose the second empty hand and experienced a shortage of peanuts as a result.

squirrel monkeys they are much less agile than capuchins, with limited thumb rotation, but can counter their thumbs. So, you are still familiar with the hidden thumb that interacts with your fingers. However, they cannot perform a “precise hold” in the same way as capuchins and humans.

However squirrel monkeys they were commonly fooled by seemingly disappearing mealworms (cheated 93% of the time). ” squirrel monkeys they can’t understand exactly, but they were fooled anyway. This suggests that the monkey does not need to be an expert in movement to be able to predict it, it is enough that it is able to do it with wide movements, ”says Garcia-Pelegrin.

monkey they do not have opposing thumbs, instead their thumbs align with the others to form five equidistant toes ideal for climbing thick tree trunks. Marmosets were rarely caught by magic (only 6% of cases). They simply chose the hand in which they put the marshmallow and held it.

Team’s previous work Cambridge show that species without arms, in this case birds of the corvid family, that is, Eurasian jays, make decisions similar to those of marmosets when faced with french drop.

The team also attempted to annul tricks actually completing melee transitions rather than ruining the French drop. This time cappuccino And squirrel monkeys properly expected and lunchtime, and monkey they failed.

Europe Press