Theory of a monkey mind

Thinking Monkey1

It is often said that the way humans make and use tools is perhaps what sets our species apart more than anything else. Now, two psychologists argue that the one thing apes and monkeys really miss, is a concept of information that’s untrue or different from what they already know.

This doesn't mean our fellow primates don't have a 'theory of mind'—an understanding that others have their own mental states, their own beliefs and desires and their own ways of viewing the world. Alia Martin and Laurie Santos from Yale University explain that they do, but it’s different to ours in one crucial respect. The duo argue that other primates “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.


In the 1990s, many scientists claimed that other primates don’t have a theory of mind at all, but based that claim on overly convoluted experiments. In the 2000s, by testing animals on simpler tasks that better reflect the challenges they naturally face, researchers showed that chimps know what their peers know, and can appreciate their goals and intentions.

More recent research, conducted at the German Primate Center in Göttingen, Germany, suggests that much like humans do, our primate cousins become more socially selective with age as well, preferring the companionship of their 'friends' to monkeys that are less familiar. The work entailed observing the behaviors of over 100 Barbary macaque monkeys, an out-going, some might say 'screechy,' species hailing from North Africa.

In another study, scientists from the UK and Italy compared instances of aggression between groups - known as intergroup contest competition - with behaviours known to strengthen social bonds within groups, such as grooming. Their research suggests our closest primate relatives may have evolved 'us versus them' social traits as a means to cope with competition from rival groups of monkeys long before this behaviour first occurred in humans.

Research has also shown that rhesus monkeys spontaneously recognize when they are ignorant and need to seek out more information. “Metacognition — the ability to think about our own thoughts— has long been considered a hallmark of being human,” says Santos. “We all know the difference between feeling like we know something for sure and feeling like we’re not all that certain. We know when we need to Google something. Monkeys have that same feeling of certainty and uncertainty themselves.”

More information: Animal vision

However, a number of recent studies have highlighted the differences between a primate's theory of mind and ours. Imagine that a mother leaves a cookie beneath a plate, and her mischievous son hides it under the table. When she returns, he’s giggling to himself. He expects her to search for the cookie in the wrong place. If she doesn’t, and looks under the table instead, he is surprised. He might do a double-take. Indeed, that’s exactly what human infants do in this situation, from a very early age. But it’s not what other primates do. Chimps and monkeys all consistently fail at these 'false belief' tasks. “Even adult monkeys lack these skills that 12-month-old infants have,” says Santos.

Santos originally thought that while non-human primates don’t understand false beliefs, they can reason about another individual’s knowledge and ignorance. That’s a view shared by other scientists who have done similar studies. But Santos now thinks that she was wrong. She and Martin argue that our closest relatives have no concept of ignorance at all. They know stuff. They can reflect on what they know. They can track if others know the same things as them. But if others don’t share the same knowledge, they’re at a loss.

“They just have no prediction about what’s going on,” says Santos. “They can’t simulate a world that’s not the world they’re in right now. The crazy thing is that this ability gets them really far. They can deceive each other. This dumb system lets you be an organism that’s pretty good at Machiavellian tasks.”

All this is part of a broader philosophical debate about how we view other animals. Many have tried to show certain traits are uniquely human, perhaps in a narcissistic quest to establish our superiority over the rest of nature. Others see more similarities than differences. When watching primates in the wild, it looks as if they’re going through the same things we are. But they’re doing it very differently.

They’re not talking like we are, and therefore they can't have thoughts the same way we have. Like most animals, with the exception of some birds, they don't know how to dance: They can't move in sync with a rythm and predict the next beat, a skill that could be associated with language. Their hands are good for climbing as well as for making tools, but they're not using technology like us. But eventually, it’s the combination of similarities and difference that will tell us the most.

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Source: The Atlantic

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