Opening up the simulation machine

Use your hand to pick something up. In a split-second your brain had to work out where to put your hand, where to position your fingertips, and how tightly to grip. Computers are smart – but it is not easy to teach a computer to do this. Your brain is much smarter than a computer. Your brain used a trick – it ran a simulation about the object. Before you picked it up, your brain thought ‘it’s this size, this shape, weighs so-and-so much…’ and so on. Another way of saying simulation is a practice run, which exists only inside your mind. Your brain is the fastest and most advanced simulation machine that has ever existed.

How did your brain make this simulation? Partly from perception, which is what your senses told you. And partly from memory, which is what your past experience and learning told you. If you saw the object before you picked it up, your brain got a visual perception, and made some guesses based on how it looked. Also, your brain compared the image with your memory to work out what the object was, and make some guesses based on your past experience (‘it looks like a phone, probably weighs this much…’). As soon as you touched the object, your brain got a tactile perception and updated the simulation (‘ok the case is quite smooth, better hold on a bit tighter’). Even if you didn’t see the object before you picked it up, your probably knew what it was as soon as you touched it. That’s how smart your brain is.

This is how it is all supposed to work, but sometimes it goes wrong. If I asked you to pick up a tennis ball which I had secretly filled with cement, you would probably fumble the first time, because you would have expected it to be lighter. Of course, that is a silly example, but it shows how your brain’s trick of using a simulation can sometimes lead to mistakes. But for people who have neurological conditions, these kinds of issues can be very real, and disabling. What if the brain couldn’t make sense of information from the eyes (as often happens in Alzheimer’s disease), or if the nerves carrying touch sensation were damaged (which is common in multiple sclerosis)? Or what if the workings of the simulation machine itself were damaged, as can happen in many different conditions? You can see how this would affect the function of the hands, which would have a big effect on daily life. And not just the hands – your brain uses simulations for everything, including walking, talking, eating, and interacting with other people. 

This is why it is important to understand how our brain’s simulation machine works. If we understand how it works, maybe we can understand why it sometimes doesn’t work, and then work out how to fix it. The strange thing is that we have only one tool to study the brain, and that is our own brains! If we put all our brains together, we might have a better chance of solving the problem.