Most people identify their intelligence with their conscious mind. That’s the part that knows it’s intelligent. That’s the part that understands and makes decisions. But looking closely, there’s plenty of intelligent things we do below the conscious level. Perhaps the most striking example is movement. We use our bones and muscles continuously during our waking hours. We learn complex motor skills and perform them over and over again with great precision and reliability. Yet, we rarely think about how we do those things. It’s actually an under-appreciated superpower that helps us multitask, overcome injuries, and adapt to new opportunities over evolutionary time. How does that work, and what does it teach us about intelligence?
The human body is a large and complex machine. Over 200 bones give our bodies shape, support their bulk, and articulate through 400 joints. Over 600 muscles hold those bones together, move them relative to each other, and maintain position and posture. Unlike a building with a rigid, static structure, the body is like a floppy ragdoll. It can only hold a shape through the constant effort of its muscles. Imagine a team of circus workers, lifting a long tent pole by ropes tied to the top. They work together to overcome gravity, hoisting the heavy thing and keeping it in a precarious upright position. They carefully balance the forces from all directions, adjusting how hard they pull to keep the pole vertical, even compensating for the wind if necessary. Now imagine another tent pole balanced on top of that one. Then another, and another… it’s pretty amazing that the body can perform this feat at all.
And that’s just for standing still. Actually moving the body in useful ways is much more difficult. It requires the same coordination of many muscles, balancing and constantly adjusting their effort to hold a bone in position, but now the joints need to move. The body must choreograph, synchronize, and precision control dozens of muscles for even small, subtle movements. Thankfully, all of this is completely unconscious, because doing it manually would be a nightmare. To get a sense of this, check out the game QWOP. It’s a stupid, frustrating game, but a good illustration of the problem. It’s much easier to unconsciously control the thirty-odd muscles in each hand to type those four letters than it is to consciously control the four simulated muscles that make the QWOP guy run.
How do we do it? The brain has a dedicated subprocessor for controlling the body. The largest part of the human brain is the cortex, home to our perception, comprehension, higher level thought, and decision making. It’s a sort of general purpose computer that works across many modalities. Below that are several special-purpose brain regions that serve as an interface to the body. They are “neural networks” by definition, but with highly specialized design and function very different from the cortex. One of these brain regions is the cerebellum, and its main job is to produce precisely timed sequences of nerve impulses to control the body. We aren’t conscious of what’s happening in the cerebellum because it’s actually much older than our conscious minds. Every vertebrate has one, going back hundreds of millions of years.
The key trick to the cerebellum’s function is a feedback loop. The cerebellum doesn’t just “move the body.” It can only get it right by constantly monitoring how the body and each muscle responds to its signals, noticing any deviations from the ideal, and then adjusting its signals to compensate. This is necessary, because the body has to perform in any position, even under the influence of outside forces, even when some muscles are stiff, weak, tired, or injured. There’s no fixed control program that can work in all of those circumstances, so the cerebellum must adapt in real time. This is also how it learns. Each error is a lesson for the future. With practice, the cerebellum gets better at predicting how the body will respond to its signals, the errors get smaller, and the necessary corrections become more subtle.
As an example, my cerebellum wasn’t born knowing how to do yoga. I had to learn by trial and error. When I first tried getting into those shapes, I did a pretty bad job of it. My form was sloppy, and “wrong” in many details. My balance was precarious. My motion was awkward and jerky. I overused some muscles and neglected others entirely. But my teachers pointed out what I did wrong, and I made corrections. By performing the same motions again and again, learning what the right posture feels like and what adjustments to make, I built up muscle memory. Now I can just think “warrior II” and my body delivers effortlessly. I taught my cerebellum a new motion control program, and now I can invoke that program at will.
The real value of this unconscious mastery is how it frees up my mind. For instance, when I walk a familiar path, it’s like turning on autopilot. While my cerebellum takes care of putting one foot in front of the other, my default mode network can reflect, imagine, and make plans. This is a powerful form of multitasking, but it’s not always desired. For instance, in my yoga practice, I pay close attention to what my body is doing, even though that’s no longer necessary to perform the poses. The result is increased awareness, precision, and control in my movements, both right now and in the future. Practice lets my cerebellum refine its programming and learn layers of nuance that increase my skill level, but only if I pay attention. In other words, mastering a movement gives me the freedom to turn my mind to other things, or to focus on the performance, resulting in better quality and learning. I can’t do both at the same time.
The ability to control large, complex bodies and to think about other things at the same is amazing, but the cerebellum’s adaptability is even more important. Although some vertebrates are born knowing how to walk or swim, we all learn new ways of moving. This is how we adapt and recover after an injury, whether it’s a twisted ankle or a lost limb. It’s also how many species are able to use tools. The cerebellum doesn’t have a fixed image of the body and its limits, it can learn to contract or expand that image as needed. This also means it can learn to operate whatever body it’s born into. Vertebrates have evolved a huge range of bodies which can swim, crawl, walk, dig, climb, or fly. Each new form started off as a “birth defect,” but thanks to the adaptive powers of the cerebellum, sometimes these were not fatal flaws, but opportunities to explore new ways of living.
This is just one example of how our unconscious intelligence improves our daily lives and our ability to adapt over evolutionary time. This one happens to be part of the brain, but not the mind as we usually think of it. How does this fit with your experience? What’s it like coordinating the conscious and unconscious parts of your brain? If you’re into athletics, how do you think about training your mind as well as your body? Does this raise any more questions for you about how we think and move? If so, I’d love to hear from you in the comments.
Thinking with Nate 