The Mind: A Miracle of Prediction

How does perception interact with movement?

Photo: Miguel Salgado / Unsplash

When I think of how the mind-body connection works, I reach back to half-remembered high school biology: You want to go somewhere, or stand up, or drink some water. Neurons fire in the brain and send signals down through muscles telling them what to do. Then you do it. My lasting impression is of an utterly mechanical and static process.

But I’ve come to understand that mind-body dynamics are anything but static and mechanical. They’re instead dynamic and anticipatory, like the world’s most complex simulator. Take perception. At a basic level, perception frames how we see the world through visual cues, but when we’re driving, for example, perception gives us the ability to gauge upcoming road curvature even when we can’t see it.

According to neuroscientist and engineer Alain Berthoz and some of the researchers he cites in his book The Brain’s Sense of Movement, our perception is about movement in 3-dimensional space — not just position — including predicting future movement.

I tend to think of perception as looking at and assessing fixed points, which tracks with how I learned about the human body. You see a bend up ahead on a hiking trail, so you aim for it, walk there, and then look further for the next point. Static, mechanical. But that isn’t what happens. Instead, your brain looks at the bend and uses its edge points to inform your perception about upcoming curvature that you can’t even see. Same with driving:

“1 or 2 seconds before every bend, the gaze of a driver on a mountain road becomes fixed on the tangent inside the bend. A calculation based on these data shows that the direction of this point in relation to that of the car makes it possible to predict the curvature of the road beyond the bend. In other words, the gaze of the driver is positioned on a point such that the information supplied by the optic flow allows him to predict the curvature of the trajectory.”

The point, writes Berthoz, is that the brain doesn’t just know where the car is in relation to curvature, it “seeks to predict the curvature at a future time.” The brain creates models of expectation and fills in information gaps in order to allow action to happen.