How many times have you been in a conversation and found yourself trying to figure out what the other person is thinking? It’s quintessentially human, but is thinking about others’ minds uniquely human? And, if not, what can other animals teach us about this phenomenon?
Our ability to think about what’s going on inside other people’s heads is called theory of mind.
"If I'm trying to predict what somebody's thinking, I'm not thinking about where they're looking or what they're about to do, I'm thinking about what's going on inside their head - their intentions, their beliefs, their desires," said Laurie Santos, Director of the Comparative Cognition Laboratory and the Canine Cognition Center at Yale University. "And the crazy thing is we don't ever have evidence of that stuff. They're just concepts that are inside somebody's head."
For neurotypical individuals, this is something that comes naturally. But it's something that many on the autism spectrum struggle with, and an overactive theory of mind may be involved in schizophrenia. Some think theory of mind may be linked to language. And many psychologists say it could be "the thing" that differentiates humans from other animals.
Or, maybe not.
Santos has been testing for what she calls mind-reading in other animals. So far, her research suggests that primates understand when human researchers are, or are not, paying attention to an object. And Santos says there's emerging evidence that dogs and even some birds do similar things.
"The truth is that we don't know too much yet. There's not that many species that have been tested," Santos said. "But there's hints that at least that simple thing - paying attention to what somebody else is paying attention to - that might be the kind of thing that lots of social species from a bunch of taxonomic groups share with humans."
Doing this kind of research is tricky, though. For starters, the animals can't tell researchers what they're thinking about. Instead, scientists have to design experiments that give some insight into what an animal might be thinking. And, then, they have to make sure that their own theory of mind isn't getting in the way - that they aren't projecting thoughts onto animals who may be thinking something completely different, or nothing at all.
"We have such strong intuitions about what animals are thinking about, particularly our pets," Santos said. "Sometimes those intuitions are dead on. Oftentimes, we're correct about what our animals are thinking about. But sometimes, we're not so on."
That, says Santos, is why we need the science.