How humans construct reality

You are parched with thirst. You drink a large glass of water. Immediately your thirst is quenched. Yet the water hasn’t had time to be absorbed into your tissues where it is needed. Have you ever wondered why this is so?

Our perceptions lag reality so we rely on our expectations. It takes longer for our conscious mind to register an input (much less act on it) than it does for our senses to register change from our bodies and the world. The brain has to anticipate and be ready to act so it generates a model of the world and makes decisions based on this model. When there’s a discrepancy between prediction and reality, the brain can update the model, decide the error is chance, or update the world—by performing an action such as moving a limb. The brain decides what to do by assigning precision to its predictions. High precision elevates discrepancies: “Heads up, check this out.” Low precision does the opposite: “It’s nothing, never mind.”

Brains can overweight sensory evidence. In the brain, this means that predictions from the model are underweighted. When this happens, it impedes detection of faint patterns in ambiguous or noisy environments. It is a persuasive way to demonstrate a pervasive phenomenon called “top-down influence” upon sensory processing. A probabilistic generative model is busy trying to predict the deluge of sensory input. In an ambiguous environment there’s nothing for it to “see” as it has no prediction. But then, with the application of new knowledge, the model adjusts and the sensory input makes sense. You can try an example of this yourself using the image below.

An abstract image of a cow that's hard to identify because it is blury

If you can’t see what’s in the image, here’s a clue: it’s a cow with a big head, with its nose at the bottom of the picture and two black ears in the top left half of the image. Got it? Yes! Now you’ll never unsee it.

This phenomenon happens in many modes—hearing and taste as well. When wine is artificially colored red, people use descriptors common to red wine such as prune, tobacco, and chocolate. Oysters taste better when accompanied by sounds of the sea. It also extends to our perception of people—our expectations of others are based on our experience (our model) and we can easily fail to accurately assess someone’s knowledge or intent. Reality is an illusion.

By moving in the world, we get feedback on the accuracy of our perceptual predictions. Barbara Tversky describes experiments where people wear prismatic glasses that distort the world by turning it upside down. At first people are dizzy, clumsy, and nauseated, but after a week they adjust. This seems remarkable. But even more surprising, people who didn’t move during the course of the experiment—they were wheeled around in a chair or were handed objects—never adjusted. Our brains change with action in the world.

There is an emerging body of thought that we can think with sensations. Interoception is the ability to be aware of the inner state of the body. We all have these bodily signals but some feel them more than others. John Coates, a former Wall Street trader, now an applied physiologist, was intrigued by what made a good trader—was there a way to tell if one person had a better gut feel than another?

Coates studied a group of financial traders on a London trading floor and asked each of them to identify moments when each could feel their own heart rate. The traders that had the most awareness of their heart rate made the most money. “Our results suggest that signals from the body—the gut feelings from financial lore—contribute to success in the markets.” He found that traders who had better interoceptive awareness made more rational decisions and made more money. The speculation is that this is because the body is not subject to cognitive biases that often distort thinking.

Before you conclude that thinking using sensations from your internal organs is totally wacky, consider for a moment that the world has far more information than our conscious mind can deal with. This is one of the reasons that our thinking is affected by cognitive biases. Our implicit learning processes gather information about the world on a continuous basis and through this pattern-building process we come to know things.

Much of what we use to assemble knowledge remains submerged. We can’t explain much of this unconscious knowledge. But if you are sensitive to interoceptive signals, you may just have a superpower for tapping into this reserve of new information.

Great Human Strength: We can act without the need for our senses to provide complete information from the world.

Great Human Weakness: We can make errors or be fooled by our senses or when we are unaware that our mental model of the world is wrong.

Machine Opportunity: Designs that offer us new sensory experiences and enable access to entirely new sources of information from the world around us.

Machine Threat: Designs that amplify our perceptual errors in dangerous ways at dangerous times.