Shifra Steinberg

Aug 18, 2021

6 min read

How our brains reconstruct the visual world

Given that we see through two small, two-dimensional retinae at the backs of our eyes, it seems miraculous that we can perceive a seamless, three-dimensional visual world. What happens to the information which our photoreceptors carry through electrical signals from our retina to our brain? We seem to filter out the raw data, stitch it together, then choose what to concentrate on and what to ignore. It appears, then, that our brains, not our eyes, construct the visual world.

Though I have contemplated this point before, it really came to the forefront of my curiosity yesterday, as I was working on a clay bust. For those who don’t know what that is, a bust is a portrait intended to record the appearance of an individual. A difficult process, not so much because of the material, but primarily because of the subject. Who could’ve known how frustratingly laborious it would be to reconstruct a thing we see every day: a human face. Surely I had seen a great many faces in my lifetime, but when it came to putting pen to paper, or in my case, clay to surface, nothing other than an excessively round head with two hollow circles for the eyes came to fruition. It never struck me that the pillar of the mouth is more pronounced than the mentolabial furrow, or that the top of the ear curves all the way around and then back into it, or that the wings of the nose stretch to the laugh lines, or that the head is smaller in the front than it is in the back.

I mean, you try. Think of someone you’ve known for a long time. A parent or a friend, or anyone for that matter. Recall their appearance. If you’ve seen them recently, you’ll probably find this simple enough. Now try drawing them. Already at this point the mental image starts to evaporate from the crevices of your hippocampus. Take it one step further, picture them 10 years ago. The image you have of them then, versus the image you have of them today is probably vastly similar.

Why does it matter? In the case of facial details, it doesn’t. Not really. As long as you can tell the difference between one friend to the other, or one family member to the next, you’re good to go in the realm of etiquette and mental soundness. Or, in my case, knowing or not knowing that the head is smaller in the front than in the back will not save my life or put me out of harm’s way. It only led to frustrations and momentary self-loathing.

We often fail to see changes or details because we are not looking for them. Our brains are programmed to filter out the important from the less important, and fill in the gaps accordingly. What is and isn’t of interest to us is determined on a personal bases. To figure out what’s important, we need to retain some information over time. This is where visual memory becomes crucial. Our short term visualization pulls together information from everywhere to build a picture in our heads. We make up a schematic image of our surroundings, containing some conceptual information about the scene’s basic parts and layout. Without the brain’s constant computing of the visual world, what we see would remain a chaotic, disorderly jumble. With help of our corrective neurological mechanisms we can make order out of the disorder. Through visual memory and attention we create a fluid whole. As a result, these processes allow our brain to create our perception of a coherent, stable world.

The blind intelligence by which a sunflower relentlessly orients itself toward the light in order to survive is similar to our brain’s “blind” relentlessness towards stabilization. If we were to account for everything we saw, our brains would be over-triggered and overworked within minutes. At any moment we are only seeing what we are intending to see. It is like having hundreds of gigabits of music, movies and pictures on your computer’s hard drive, or having so many tabs open that the whole system slows down. Our brains seem to work in a similar manner. It takes shortcuts by filling in the gaps onto which we don’t put any special importance. Like the ear I spent half the day sculpting: before yesterday I did not have to know its exact anatomy. As far as I was concerned, as long as your ear is connected to your body, the details hardly matter.

We spend our day to day lives under the illusion that seeing means seeing everything, while in reality, it means hardly seeing anything at all. And while none of these examples have any real ramifications, there are plenty of stories outlining apparent moments of “blindness” which led to car accidents, or tripping over something and falling down the stairs.

There are other ramifications too. Just as the colors you see in a rainbow are but a narrow segment of a much vaster electromagnetic spectrum, what we see is quite literally not what you get. The eyes are but a narrow fragment of a much larger visual world. How much of our world remains hidden to us? Hidden, yet out in the open, evolutionarily of such little use to us, that we are literally too blind to see any of it. The position and shape of the eye can mean the difference between life and death for many animals. Predators, like lions and tigers, who hunt by ambush, have front-facing eyes, which provide better focus and a greater ability to calculate distances. Contrarily, deer and goats have lateral eyes and horizontal pupils, which grant a broader field of vision. Bats perceive the world through sonar. Detecting the reflections from objects within range of their own rapid, high-frequency shrieks. Even if we were to put a pair of glasses on that made us see like them, we would never fully know, as Thomas Nagel postulated some time ago, what it would feel like to actually be a bat. No matter how and to what lengths we stretch our imaginations, we will only ever know how to be a human bat, and not a bat in and of itself.

There is, then, a great expanse of mystery right before our eyes. In order to increase awareness, and in the process become less “blind”, we ought to become more attentive and less distracted. A difficult task, as paying attention to the small nuances in our daily lives is paradoxically the very source of many of our distractions. However, you can, I believe, train your mind towards detailed perception. Having spent three days on my clay bust, I can say with some confidence that I now look at people’s faces differently. While in the past my brain would make a schematic outline and approximate positioning of each human feature, now it looks for the details. How far are the nostrils from the laugh lines, how far is the upper lip from the nose, how pronounced are the cheekbones, and how do they connect to the ear, are all questions for which my brain is now actively looking for answers. It’s interesting to see, in action, what self-help gurus have said for so long: what we focus on, grows. And it seems to be true.

Here’s a picture of the ear I’ve been working on…