Scientists at the University of Cambridge’s Comparative Cognition Lab have studied whether non-human primates can be fooled by a French-drop-style trick that uses sleight-of-hand. In the study patricipants included capuchin, squirrel and marmoset monkeys, who were rewarded with either peanuts, mealworms or marshmallows when they correctly guessed which of the magician’s hands held the hidden morsel after he appeared to transfer it from one hand to the other. The capuchins tended to choose the empty hand, and so mostly got it wrong. The squirrels, who only possess limited thumb rotation, were tricked 93% of the time while the marmosets, who have no opposable thumbs, close to never choose the wrong hand.
https://www.cam.ac.uk/research/news/sleight-of-hand-magic-trick-only-fools-monkeys-with-opposable-thumbs