From the moment you’re born to the moment you draw your last breath, your brain is stuck in a dark, silent box called your skull. Day in and day out, it continually receives sense data from the outside world via your eyes, ears, nose, and other sensory organs. This data does not arrive in the form of the meaningful sights, smells, sounds, and other sensations that most of us experience. It’s just a barrage of light waves, chemicals, and changes in air pressure with no inherent significance.
Faced with these ambiguous scraps of sense data, your brain must somehow figure out what to do next. Your brain’s most important job is to control your body so you stay alive and well. Your brain must somehow make meaning from the onslaught of sense data it’s receiving so you don’t fall down a staircase or become lunch for some wild beast.
How does your brain decipher the sense data so it knows how to proceed? If it used only the ambiguous information that is immediately present, then you’d be swimming in a sea of uncertainty, flailing around until you figured out the best response. Luckily, your brain has an additional source of information at its disposal: memory.
Your brain asks itself in every moment, figuratively speaking, The last time I encountered a similar situation, when my body was in a similar state, what did I do next?
Your brain can draw on your lifetime of past experiences—things that have happened to you personally and things that you’ve learned about from friends, teachers, books, videos, and other sources. In the blink of an eye, your brain reconstructs bits and pieces of past experience as your neurons pass electrochemical information back and forth in an ever-shifting, complex network. Your brain assembles these bits into memories to infer the meaning of the sense data and guess what to do about it. Your past experiences include not only what happened in the world around you but also what happened inside your body. Was your heart beating quickly? Were you breathing heavily? Your brain asks itself in every moment, figuratively speaking, The
last time I encountered a similar situation, when my body was in a similar state, what did I do next? The answer need not be a perfect match for your situation, just something close enough
to give your brain an appropriate plan of action that helps you survive and even thrive.
This explains how the brain plans your body’s next action. How does your brain also conjure high-fidelity experiences out of scraps of raw data from the outside world? How does it create feelings of terror from a thundering heart? Once again, your brain recreates the past from memory by asking itself, The last time I encountered a similar situation, when my body
was in a similar state and was preparing an action similar to this one, what did I see next? What did I feel next? The answer becomes your experience. In other words, your brain combines information from outside and inside your head to produce everything you see, hear, smell, taste, and feel.
How Your Brain Predicts What You See
Here’s a quick demonstration that your memory is a critical ingredient in what you see. Take a look at the three line drawings:
Excerpted from “The Ultimate Droodles Compendium” by Roger Price.
What do you see in the drawings?
Inside your skull, without your awareness, billions of your neurons are trying to give those lines and blobs meaning. Your brain is searching through a lifetime of past experiences, issuing thousands of guesses at once, weighing probabilities, trying to answer the question, What are these wavelengths of light most like? And it’s all happening faster than you can snap your fingers.
So what do you see? A bunch of black lines and a couple of blobs? Let’s see what happens when we give your brain some more information. The first image is a spider doing a handstand, the second is a submarine going over a waterfall, and the third is a ski jump and spectators as seen by the ski jumper.
When you look back at the line drawings, you should now see familiar objects instead of lines and blobs. Your brain is assembling memories from bits and pieces of past experiences to go beyond the visual data in front of you and make meaning. In the process, your brain is literally changing the firing of its own neurons. Objects that you might never have seen before now leap from the page.
The lines and blobs haven’t changed—you have.
Artwork, particularly abstract art, is made possible because the human brain constructs what it experiences. When you view a Cubist painting by Picasso and see recognizable human figures, that happens only because you have memories of human figures that help your brain make sense of the abstract elements. The painter Marcel Duchamp once said that an artist does only 50% of the work in creating art. The remaining 50% is in the viewer’s brain (Some artists and philosophers call the second half “the beholder’s share.”).
Your brain actively constructs your experiences. Every morning, you wake up and experience a world around you full of sensations. You might feel the bedsheets against your skin. Maybe you hear sounds that woke you, like an alarm buzzing or birds chirping or your spouse snoring. Perhaps you smell coffee brewing. These sensations seem to sail right into your head as if your eyes, nose, mouth, ears, and skin were transparent windows on the world. But you don’t sense with your sensory organs. You sense with your brain.
What you see is some combination of what’s out there in the world and what’s constructed by your brain. What you hear is also some combination of what’s out there and what’s in your brain, and likewise for your other senses.
A Carefully Controlled Hallucination
In much the same way, your brain also constructs what you feel inside your body. Your aches and jitters and other inner sensations are some combination of what’s going on in your brain and what’s actually happening within your lungs and heart and gut and muscles and so on. Your brain also adds information from your past experiences to guess what those sensations mean. For instance, when people haven’t slept enough and are fatigued or low energy, they may feel hungry (because they’ve been hungry before when their energy was low) and may think that a quick snack will boost their energy. In fact, they’re just tired from lack of sleep.
This constructed experience of hunger may be one reason why people gain unwanted weight.