People like to ascribe causes to things. We do this so much that the psychologist James Alcock has postulated that one of the main functions of the human brain is to serve as a belief engine. If we find a cause for an action or event, we can go about out business thinking that some part of the world makes sense. But where does this penchant for finding causes come from? Do we always have it?

The answer is what has been called the theory of mind by developmental psychologists. Basically, the way this works is that the infant starts to make assumptions about how the world works. If I throw my sippee cup off my high chair it falls to the ground. By extension, if someone else does the same thing the sippee cup will also fall to the ground. This starts happening around 18 months of age.

Another thing happens around the same time. We start to develop a sense of self. A child around this age will recognize her reflection in a Mirror. The child no longer thinks that the reflection is another child. This is contrasted with an animal such as a dog which spooks when it sees its reflection in a patio window. The dog makes the erroneous assumption that the reflection is another dog and starts barking.

So, it seems that our sense of self is intrinsically linked to our theory of mind. When we begin to see ourselves as individuals we can then start seeing other people as separate entities. This might seem simplistic but it’s something that we internalize without even realizing it. A person who does not develop a “normal” theory of mind would have trouble understanding the motives and actions of other people.

This brings us to autism. In recent years, it has been hypothesized that people with autism do not develop a theory of mind the same way other people do. There is actually physiological evidence to support this. Specific Neurons were discovered that fired when a monkey picked up a cup. Interestingly, these same neurons would fire if the monkey watched another monkey pick up a cup. As a result these neurons were initially called “monkey see, monkey do” neurons. They are now usually referred to as Mirror Neurons.

Now the interesting thing about mirror neurons is that they don’t just respond to actions. They are also involved with empathy. If your friend is sad, you can feel the same thing they do, so to speak, because your mirror neurons become activated by their apparent sadness. In a way then, mirror neurons help make us human.

One of the main problems reported with people who have autism is that they appear to lack empathy and often have impaired social interaction with other people. This has bolstered the case that autism is partly due to a deficit in the mirror neuron system. I say partly because it’s assuredly due to a complex interaction between genetic and environmental factors as well.

So you see, when your child begins to acquire a sense of self it’s a sign that they are developmentally on the right track. Their mirror neurons are working full throttle as they learn to mimic the actions of other people and start to empathize with others as well. Without this happening, your child wouldn’t understand you telling them that it’s not a good idea to tease their friend because they wouldn’t like it if they did that to them. We couldn’t put ourselves in “someone else’s shoes” without mirror neurons and a normally developed theory of mind.