theatlantic | You’re holding a surprise party for a friend. The door opens, the lights flick on, everyone leaps out... and your friend stands there silent and unmoved. Now,you’re the one who’s surprised. You assumed she had no idea, and based on that, you made a (wrong) prediction about how she would react. You were counting on her ignorance. This ability to understand that someone else might be missing certain information about the world comes so naturally to us that describing it feels mundane and trite.
And yet, according to two psychologists, it’s a skill that only humans have. “We think monkeys can’t do that,” says Alia Martin from Victoria University of Wellington.
This claim is the latest volley in a long debate about how our fellow primates understand each other. Of particular interest is the question: Do they have a “theory of mind”—an understanding that others have their own mental states, their own beliefs and desires, their own ways of viewing the world?
Yes they do, say Martin and Laurie Santos from Yale University. But it’s different to ours in one crucial respect. The duo argue that other primates “have no concept of information that’s untrue or different [from] what they know.” That means, one, that they can’t conceive of states of the world that are decoupled from their current reality. And so, they can't imagine other individuals thinking about the world in a different way. They can think about the minds of others, but only when those minds have the same contents as theirs.
Put it this way: If a chimp sees other chimps staring at an apple on a ledge, it understands that they’re aware of the apple and might reach across to eat it—a basic theory of mind. But it can’t imagine what would happen if the apple was on the floor, or if the apple was a banana, or if its peers mistook the apple for something else.
“We might be the only species that can think about things that aren’t facts we have about the world, about other possible worlds, about states in the past or future, about counterfactuals,” says Santos. “We can simulate a whole fictional world. And if you’re a species that can get outside your own head, you can apply that to other people.” A chimp won't wonder if it'll be hungry tomorrow. It only cares if it's hungry now. An orangutan isn't going to write a novel, because this is the only reality that it knows.