Incognito (13 page)

Spend a moment thinking about the most beautiful person you know. It would seem impossible for eyes to gaze upon this person and not be intoxicated with
attraction. But everything depends on the evolutionary program those eyes are connected to. If the eyes belong to a frog, this person can stand in front of it all day—even naked—and will attract no attention, perhaps only a bit of suspicion. And the lack of interest is mutual: humans are attracted to humans, frogs to frogs.

Nothing seems more natural than
desire, but the first thing to notice is that we’re wired only for species-appropriate desire. This underscores a simple but crucial point: the brain’s circuits are designed to generate behavior that is appropriate to our survival. Apples and eggs and potatoes taste good to us not because the shapes of their molecules are inherently wonderful, but because they’re perfect little packages of sugars and proteins: energy dollars you can store in your bank. Because those foods are useful, we are engineered to find them tasty. Because fecal matter contains harmful microbes, we have developed a hardwired aversion to eating it. Note that baby koalas—known as joeys—eat their mother’s fecal matter to obtain the right bacteria for their digestive systems. These bacteria are necessary for the joeys to survive on otherwise-poisonous eucalyptus leaves. If I had to guess, I’d say
that fecal matter tastes as delicious to the joey as an apple does to you. Nothing is inherently tasty or repulsive—it depends on your needs. Deliciousness is simply an index of usefulness.

Many people are already familiar with these concepts of attraction or tastiness, but it is often difficult to appreciate how deep this evolutionary carving goes. It’s not simply that you are attracted to humans over frogs or that you like apples more than fecal matter—these same principles of hardwired thought guidance apply to all of your deeply held beliefs about logic, economics, ethics, emotions, beauty, social interactions, love, and the rest of your vast mental landscape. Our evolutionary
goals navigate and structure our thoughts. Chew on that for a moment. It means there are certain kinds of thoughts we
can
think, and whole categories of thoughts we cannot. Let’s begin with all the thoughts you didn’t even know you were missing.

In 1670,
Blaise Pascal noted with awe that “man is equally incapable of seeing the nothingness from which he emerges and the infinity in which he is engulfed.”
¹
Pascal recognized that we spend our lives on a thin slice between the unimaginably small scales of the atoms that compose us and the infinitely large scales of galaxies.

But Pascal didn’t know the half of it. Forget atoms and galaxies—we can’t even see most of the action at our
own
spatial scales. Take what we call visible light. We have specialized receptors in the backs of our eyes that are optimized for capturing the
electromagnetic radiation that bounces off objects. When these receptors catch some radiation, they launch a salvo of signals into the brain. But we do not perceive the
entire
electromagnetic spectrum, only
a part of it. The part of the light spectrum that is visible to us is less than a ten-trillionth of it. The rest of the spectrum––carrying TV shows, radio signals, microwaves, X-rays, gamma rays, cell phone conversations, and so on––flows through us with no awareness on our part.
²
CNN news is passing through your body right now and you are utterly blind to it, because you have no specialized receptors for that part of the spectrum. Honeybees, by contrast, include information carried on ultraviolet wavelengths in their reality, and rattlesnakes include infrared in their view of the world. Machines in the hospital see the X-ray range, and machines in the dashboard of your car see the radio frequency range. But you can’t sense any of these. Even though it’s the same “stuff”—electromagnetic radiation—you don’t come equipped with the proper sensors. No matter how hard you try, you’re not going to pick up signals in the rest of the range.

What you are able to experience is completely limited by your biology. This differs from the commonsense view that our eyes, ears, and fingers passively receive an objective physical world outside of ourselves. As science marches forward with machines that can see what we can’t, it has become clear that our brains sample just a small bit of the surrounding physical world. In 1909, the Baltic German biologist Jakob von Uexküll began to notice that different animals in the same ecosystem pick up on different signals from their environment.
³
In the blind and deaf world of the tick, the important signals are temperature and the odor of butyric acid. For the black ghost knifefish, it’s electrical fields. For the echolocating bat, air-compression waves. So von Uexküll introduced a new concept: the part that you are able to see is known as the
umwelt
(the environment, or surrounding world), and the bigger reality (if there is such a thing) is known as the
umgebung
.

Each organism has its own umwelt, which it presumably assumes to be the entire objective reality “out there.” Why would we ever stop to think that there is more beyond what we can sense? In the movie
The Truman Show
, the eponymous Truman lives in a world completely constructed around him (often on the fly) by an intrepid
television producer. At one point an interviewer asks the producer, “Why do you think Truman has never come close to discovering the true nature of his world?” The producer replies, “We accept the reality of the world with which we’re presented.” He hit the nail on the head. We accept the umwelt and stop there.

Ask yourself what it would be like to have been blind from birth. Really think about this for a moment. If your guess is “it would something like blackness” or “something like a dark hole where vision should be,” you’re wrong. To understand why, imagine you’re a scent dog such as a bloodhound. Your long nose houses two hundred million scent receptors. On the outside, your wet nostrils attract and trap scent molecules. The slits at the corners of each nostril flare out to allow more air flow as you sniff. Even your floppy ears drag along the ground and kick up scent molecules. Your world is all about smelling. One afternoon, as you’re following your master, you stop in your tracks with a revelation. What is it like to have the pitiful, impoverished nose of a human being? What can humans possibly detect when they take in a feeble little noseful of air? Do they suffer a blackness? A hole of smell where smell is supposed to be?

Because you’re a human, you know the answer is no. There is no hole or blackness or missing feeling where the scent is absent. You accept your reality as it’s presented to you. Because you don’t have the smelling capabilities of a bloodhound, it doesn’t even strike you that things could be different. The same goes for people with
color
blindness: until they learn that others can see hues they cannot, the thought does not even hit their radar screen.

If you are not color-blind, you may well find it difficult to imagine yourself as color-blind. But recall what we learned earlier: that some people see
more
colors than you do. A fraction of women have not just three but four types of color photoreceptors—and as a result they can distinguish colors that the majority of humankind will never differentiate.
⁴
If you are not a member of that small female population, then you have just discovered something about your own impoverishments that you were unaware
of. You may not have thought of yourself as color-blind, but to those ladies supersensitive to hues, you are. In the end, it does not ruin your day; instead, it only makes you wonder how someone else can see the world so strangely.

And so it goes for the congenitally blind. They are not missing anything; they do not see blackness where vision is missing. Vision was never part of their reality in the first place, and they miss it only as much as you miss the extra scents of the bloodhound dog or the extra colors of the tetrachromatic women.

There is a large difference between the umwelts of humans and those of ticks and bloodhounds, but there can even be quite a bit of individual variability between humans. Most people, during some late-night departure from quotidian thinking, ask their friends the following sort of question: How do I know that what I experience as red and what you experience as red is the same thing? This is a good question, because as long as we agree on labeling some feature “red” in the outside world, it doesn’t matter if the swatch experienced by you is what I internally perceive as canary yellow. I call it red, you call it red, and we can appropriately transact over a hand of poker.

But the problem actually runs deeper. What I call vision and what you call vision might be different—mine might be upside down compared to yours, and we would never know. And it wouldn’t matter, as long as we agree on what to call things and how to point to them and where to navigate in the outside world.

This sort of question used to live in the realm of philosophical speculation, but it has now been promoted to the realm of scientific experiment. After all, across the population there are slight differences in brain function, and sometimes these translate directly into different ways of experiencing the world. And each individual believes his way is
reality
. To get a sense of this, imagine a world of magenta Tuesdays, tastes that have shapes, and wavy green
symphonies. One in a hundred otherwise normal people experience the world this way, because of a condition called synesthesia (meaning “joined sensation”).
⁵
In synesthetes, stimulation of a sense triggers an anomalous sensory experience: one may hear colors, taste shapes, or systematically experience other sensory blendings. For example, a voice or music may not only be heard but also seen, tasted, or felt as a touch. Synesthesia is a fusion of different sensory perceptions: the feel of sandpaper might evoke an F-sharp, the taste of chicken might be accompanied by a feeling of pinpoints on the fingertips, or a symphony might be experienced in blues and golds. Synesthetes are so accustomed to the effects that they are surprised to find that others do not share their experiences. These synesthetic experiences are not abnormal in any pathological sense; they are simply unusual in a statistical sense.

Synesthesia comes in many varieties, and having one type gives you a high chance of having a second or third type. Experiencing the days of the week in color is the most common manifestation of synesthesia, followed by colored letters and numbers. Other common varieties include tasted words, colored hearing, number lines perceived as three-dimensional forms, and letters and numerals experienced as having gender and personalities.
⁶

Synesthetic perceptions are involuntary, automatic, and consistent over time. The perceptions are typically basic, meaning that what is sensed is something like a simple color, shape, or texture, rather than something pictorial or specific (for example, synesthetes don’t say, “This music makes me experience a vase of flowers on a restaurant table”).

Why do some people see the world this way? Synesthesia is the result of increased cross talk among sensory areas in the brain. Think of it like neighboring countries with porous borders on the brain’s map. And this cross talk results from tiny genetic changes that pass down family lineages. Think about that: microscopic changes in brain wiring can lead to different realities.
⁷
The mere existence of synesthesia demonstrates that more than one kind of brain—and one kind of mind—is possible.

Let’s zoom in on a particular form of synesthesia as an example. For most of us, February and Wednesday do not have any particular place in space. But some synesthetes experience precise locations in relation to their bodies for numbers, time units, and other concepts involving sequence or ordinality. They can point to the spot where the number 32 is, where December floats, or where the year 1966 lies.
⁸
These objectified three-dimensional sequences are commonly called
number forms, although more precisely the phenomenon is called
spatial sequence synesthesia.
⁹
The most common types of spatial sequence synesthesia involve days of the week, months of the year, the counting integers, or years grouped by decade. In addition to these common types, researchers have encountered spatial configurations for shoe and clothing sizes, baseball statistics, historical eras, salaries, TV channels, temperature, and more. Some individuals possess a form for only one sequence; others have forms for more than a dozen. Like all synesthetes, they express amazement that not everyone visualizes sequences the way they do. If you are not synesthetic yourself, the twist is this: it is difficult for synesthetes to understand how people cope
without
a visualization of time. Your reality is as strange to them as theirs is to you. They accept the reality presented to them, as you do yours.
¹⁰

Nonsynesthetes often imagine that sensing extra colors, textures, and spatial configurations would somehow be a perceptual burden: “Doesn’t it drive them crazy having to cope with all the extra bits?” some people ask. But the situation is no different from a color-blind person telling a person with normal vision, “You poor thing. Everywhere you look you’re always seeing colors. Doesn’t it drive you crazy to have to see everything in
colors
?” The answer is that colors do not drive us crazy, because seeing in color is normal to most people and constitutes what we accept as reality. In the same way, synesthetes are not driven crazy by the extra dimensions. They’ve never known reality to be anything else. Most synesthetes live their entire lives never knowing that others see the world differently than they do.