"Fool me once, shame on you. Fool me twice, shame on me."
A recent study has found that ravens understand this principle as much as we do. When a human cheats a raven, the bird remembers the experience and refuses to deal with that person in the future.
Common ravens (Corvus corax) are one of the smartest birds on earth. Not only can they solve puzzles, find long cached food, and remember their own complex social structures, but they recognize our faces and understand reciprocity with humans.
To test the ravens' memory of fair play, researchers worked with ravens in an aviary in Austria. The goal was two-fold: (1) Can ravens remember who acted cooperatively or defectively in a single session? and (2) Can ravens who observe an interaction but have no first-hand experience remember who's who and act accordingly?
Before the experiment began the ravens learned to offer bread to a human and receive cheese in return. They love cheese.
The experiment involved one-on-one interactions with women the birds had never met before. A woman faced the raven and held out an empty hand to receive bread while displaying a piece of cheese in her other hand. A "fair" experimenter received the bread, then gave the cheese to the raven. A "deceiver" received the bread but ate the cheese herself.
Cheated ravens were outraged! Every one of them vocalized and hopped around, then ate or hid his remaining bread so the cheater couldn't get to it.
A month later the same experimenters tried the exchange again. The ravens remembered the people who cheated them and refused to deal with them.
Did ravens who observed the cheating behavior avoid the deceivers? Not really, but this doesn't mean they were stupid. We humans do it, too. "She cheated him but she won't cheat me." Hah!
So it comes down to personal experience: Fool me once, shame on you. Fool me twice, shame on me.
(photo from Wikimedia Commons; click on the image to see the original)