In the movie Unbreakable by M. Night Shyamalan, the villain Elijah Price says, “It’s hard for many people to believe that there are extraordinary things inside themselves, as well as others.” Indeed, the story’s superhero, David Dunn, is unaware of his super strength, his inability to be injured (except by drowning), and his ability to sense evil. Dunn would have lived his life without anyoneincluding himselfrealizing he had superpowers if Unbreakable’s villain hadn’t forced him into the discovery.
At first glance we are surprised that Dunn could be so in the dark about his abilities. How could he utilize his evil-detection power every day at work as a security guard without realizing he had it? However, aren’t most powerssuper or otherwiselike that? For example, our ability to simply stand requires complex computations about which we are unaware. Complex machines like David Dunn and ourselves only function because we have a tremendous number of “powers” working in concert, but we can only be conscious of a few of these powers at a time. Natural selection has seen to it that precious consciousness is devoted where it’s most neededand least harmfulleaving everything else running unnoticed just under the surface.
The involuntary functions of our bodies rarely announce their specific purposes. Livers never told anyone they’re for detoxification, and they don’t come with user’s manuals. Neurosurgeons have yet to find any piece of brain with a label reading, “Crucial for future-seeing. Do not remove without medical or clerical consultation.” The functions of our body are carried out by unlabeled meat, and no gadgetno matter how fancycan allow us to simply read off those functions in a lab.
Powers are even harder to pin down, however, because they typically work superbly only when we’re using them where and when we’re supposed to. Our abilities evolved over millions of years to help us survive and reproduce in nature, and so you can’t understand them without understanding the environment they evolved for, any more than you can understand a stapler without knowing what paper is.
Superpowers, then, can’t be introspected. They can’t be seen with a microscope. And they can’t be grasped simply by knowing the ins and outs of the meat. Instead, the natural environment is half the story. Lucky for us there are ways of finding our powers. Science lets us generate a hypothesis concerning the purpose of some biological structurewhat its power isand then test that hypothesis and its predictions. Those predictions might concern how the power would vary with habitat, what other characteristics an animal with that power would be expected to have, or even what that biological structure would look like were it really designed with that power in mind. That’s how we scientists identify structures’ powers.
And that’s what this scientist is doing in this book: identifying powers. Specifically, superpowers. Even more specifically, superpowers of visionfour of them, one from each of the main subdisciplines of vision: color, binocularity, motion, and object recognition. Or in superhero terms: telepathy, X-ray vision, future-seeing, and spirit-reading. Now, you might be thinking, “How could we possibly have such powers? Mustn’t this author be crazy to suggest such a thing?” Let me immediately allay your fears: there’s nothing spooky going on in this book. I’m claiming we have these four superpowers, yes, but also that they are carried out by our real bodies and brains, with no mysterious mechanisms, no magic, and no funny business. Trust meI’m a square, stick-in-the-mud, pencil-necked scientist who gets annoyed when one of the cable science channels puts a show on about “hauntings,” “mystics,” or other nonsense.
But then why am I writing about superpowers? “No magic, no superpowers,” some might say. Well, perhaps. But I’m more inclined to say, “No magic, but still superpowers.” I call each of these four powers “superpowers” because each of them has been attributed to superhuman characters, and each of them has been presumed to be well beyond the limits of us regular folk.
That we have superpowers of visionand yet no one has realized itis one of the reasons I think you’ll enjoy this book. Superpowers are fun, after all. There’s no denying it. But superpowers are just a part of this book’s story. Each of the four superpowers is the tip of an iceberg, and lying below the surface is a fundamental question concerning our nature. This book is really about answering “why”: Why do we see in color? Why do our eyes face forward? Why do we see illusions? Why are letters shaped the way they are?
What on Earth is the connection between these four deep scientific questions and the four superpowers? I’d hate to give away all the answers nowthat’s what the rest of the book is forbut here are some teasers. We use color vision to see skin, so we can sense the emotions and states of our friends and enemies (telepathy). Our eyes face forward so that we can see through objects, whether our own noses or clutter in the world around us (X-ray vision). We see illusions because our brain is attempting to see the future in order to properly perceive the present (future-seeing). And, lastly, letters have culturally evolved over centuries into shapes that look like things in nature because nature is what we have evolved to be good at seeing. These letters then allow us to effortlessly read the thoughts of the living . . . and the dead (spirit-reading).
Although the stories behind these superpowers concern vision, they are more generally about the brain and its evolution. Half of your brain is specialized for performing the computations needed for visual perception, and so you can’t study the brain without spending about half your energies on vision; you won’t miss out on nearly as much by skipping over audition and olfaction. And not only is our brain “half visual,” but our visual system is by far the most well-understood part of our brains. For a century, vision researchers in an area called visual psychophysics have been charting the relationship between the stimuli in front of the eye and the resultant perception elicited “behind” them, in the brain. For decades neuroanatomists such as John Allman, Jon Kaas, and David Van Essen have been mapping the visual areas of the primate brain, and countless other researchers have been characterizing the functional specializations and mechanisms within these areas. Furthermore, understanding the “why” of the brain requires understanding our brain’s evolution and the natural ecological conditions that prevailed during evolution, and these, too, are much better understood for vision than for our other senses and cognitive and behavioral attributes. Although about half the brain may be used for vision, much more than half of the best understood parts of the brain involve vision, making vision part and parcel of any worthwhile attempt to understand the brain.
And who am I, in addition to being a square, stick-in-the-mud, pencil-necked cable viewer? I’m a theoretical neuroscientist, meaning I use my training in physics and mathematics to put forth and test novel theories within neuroscience. But more specifically, I am interested in addressing the function and design of the brain, body, behaviors, and perceptions. What I find exciting about biology and neuroscience is why things are the way they are, not how they actually work. If you describe to me the brain mechanisms underlying our perception of color, I’ll still be left with what I take to be the most important issue: Why did we evolve mechanisms that implement that kind of perception in the first place? That question gets at the ultimate reasons for why we are as we are, rather than the proximate mechanical reasons (which make my eyes glaze over). In attempting to answer such “why” questions I have also had to study evolution, for only by understanding it and the ecological conditions wherein the trait (e.g., color vision) evolved can one come to an ultimate answer. So I suppose that makes me an evolutionary theoretical neuroscientist. That’s why this book is not only about four novel ideas in vision science, but puts an emphasis on the “evolution” in “revolution.”
But enough with the introductions. Let’s get started. Or perhaps I should say . . . up, up, and away!