A question of balance, part 1

We have plans to use that pressure sensitive mat I wrote about in a recent post to help people who may have trouble with balance.

Because of this, I’ve been learning a lot about how people balance on their feet — and why we don’t just fall over. It turns out there are at least four distinct sensing systems we use for this.

Our eyes give us continual feedback about which direction is up. Meanwhile, our inner ear (the vestibular system) gives us inertial feedback. Our sense of proprioception (roughly speaking, knowing the positions of your arms, legs, torso, etc., without needing to look) helps us to know whether our body is in balance. And finally, we use touch sensations in our toes and the bottoms of our soles to know how our weight is distributed over our feet.

These are completely separate biological systems, which function through wildly different mechanisms. And yet they all operate in concert to help us stay upright. Nature is very good at being redundant when it’s important.

As you get older, each of these systems starts to work less well. Yet because of all this redundancy, you have a good chance of keeping your balance at even a quite advanced age, if you exercise properly (but not if you don’t exercise properly).

I’ve been thinking about this question of how we balance, and I think it generalizes to other aspects of the human condition. More tomorrow.

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