What is theory of mind?

The concept of theory of mind has its roots in evolutionary biology. The term was first coined in a 1978 paper by primate researchers who concluded that higher apes like chimpanzees couldn't understand the mental states that lead to action on others' parts, though later research has found that they likely can [source: Call and Tomasello].

So what is the evolutionary benefit of theory of mind? As communications professor Francis F. Steen describes it, by considering others' motives to predict their actions, an animal can determine whether a predator is moving toward it to attack and eat the animal. Conversely, when it appears the predator is too hot to move on a particularly warm day, such a mechanism allows the animal -- which is likely hot, too -- to rest easy as well and not expend any unnecessary energy running away from a predator that has no interest in pursuing it [source: Steen]. Anyone who has seen footage of a lion and a gazelle lying down, panting and watching one another only yards apart has seen this mechanism in action.

But comparing a gazelle's ability to predict whether a lion is in a mood to attack with human folk psychology is slightly off base. Cognitive researchers don't necessarily believe that animals like gazelles and lions possess theory of mind. They consider only humans and most likely higher apes in possession of this far more advanced intellectual analysis. More to the point, if you've ever looked at a lion and considered that it looked happy or that it wished it were free, you've just proven yourself capable of the kind of higher order thinking that theory of mind is based on.

In fact, the example using the gazelle is a rival to theory of mind as an explanation for how humans carry out folk psychology. This animalian concept, called mental simulation, says that we predict others' goals and actions based on creating mental constructs of what we would do if we were in their shoes. We use our past experiences to create a mental model of the situation, essentially using our brains' processing power to analyze the available data and then make our prediction [source: Marraffa].

What differentiates theory of mind from simulation and other explanations for how we arrive at our ability to carry out folk psychology is fairly nuanced. Theory of mind says that we practice folk psychology by forming ideas about what other people believe at any given moment. And recent findings in autism research have lent support to the theory-theory.

Theory of mind stands apart from other theories that seek to explain how we can attribute mental states to those we deem as "others." Specifically, it states that at some point around age 3 or 4, we become aware that other people hold different attitudes, beliefs and knowledge than we do. It becomes apparent to our minds that knowledge can be compartmentalized (we may know something someone else doesn't and vice versa). We realize that there is such a thing as pretense (the ability to create falsehoods). And we realize that other people may feel differently than us, meaning we do not all share the same mental and emotional states and beliefs simultaneously. This is the first, huge step toward metacognition, or thinking about thinking [source: Wiley-Blackwell].

The skills associated with theory of mind don't emerge in all humans. People on the autism spectrum have long been observed to have mindblindness, characterized as an inability to consider others' points of view, wants, needs and desires. This has often been linked to a lack of empathy, although that idea has come under fire in recent years. Instead, researchers have come to believe that people with autism lack theory of mind skills.

To test this, researchers have given autistic children false-belief tests. These tests go something like this:

Sally is playing with her ball in her room. She gets up to go to the kitchen for a while and places the ball in her top dresser drawer. While she's gone, her mother comes in Sally's room and moves the ball from the dresser drawer to the toy box. When Sally comes back from the kitchen, where will she look for her ball?

A neurotypical child would correctly guess that Sally would look in the drawer for her ball, since that's where she left it. This answer shows a child has developed an awareness that others may not have knowledge she has, a hallmark of theory of mind. Although that child knows Sally's mother moved the ball, Sally doesn't. Children with autism generally tend to answer that Sally will look in the toy box, which is where they know the ball has been moved.

Autistic children are even more prone to fail second-order false belief test. These elaborate on the Sally test, where children are asked what they think a second character thinks about another character; for example, what John thinks Todd knows is in his lunch box [source: Baron-Cohen].

Theory of mind is an interesting concept. Perhaps further study of autism itself will yield more answers to how we arrive at that amazing state of being able to think about others.