Nobody likes to be deceived, especially when there’s food involved. And most great apes, as well as two-and-a-half-year-old kids, can tell when someone is trying to fake them out of a bigger pretzel stick, a team of German primatologists have discovered.It’s the first time orangutans, bonobos and gorillas have been shown to discriminate between appearance and reality.
Karg and her colleagues confirmed the results of a previous study showing that chimpanzees are no slouches at seeing through a false appearance, either. Using sticks of food, the researchers set up a series of tests designed to measure the ability of an ape to discriminate reality from illusion. The goal of each test was simple: Pick the biggest stick. But what looked like the longest stick wasn’t always actually the biggest, the scientists used a sliding board to alter the sticks’ appearances, similar to the way a carton obscures all but the tips of french fries. During the tests, the board made a long stick seem small and the small stick seem long. (It showed 0.8 inches of a 5-inch pretzel but 1.6 inches of a 2.5-inch stick.)