Scientists recently put the masked mammals through the Aesop's Fable test, which measures if animals can discern cause and effect by displacing water to access food.

The experiment is based on the story in which a thirsty crow can’t drink from a pitcher with a low level of water. By dropping in stones, the bird raises the water level and is able to drink. (Related: "Watch Clever Birds Solve a Challenge From Aesop's Fables.")

In the new study, the researchers presented captive raccoons with a cylinder containing a floating marshmallow that was too low to grab. Next, they showed the raccoons how dropping stones in the water would raise the marshmallow.

Two of the eight raccoons successfully repeated the behavior, dropping the