“Over seven billion human brains traffic the planet today. Although we typically feel like independent operators, each of our brains operates in a rich web of interaction with one another—so much so that we can plausibly look at the accomplishments of our species as the deeds of a single, shifting, meta-organism.”
The Brain: The Story of You, Dr. David Eagleman

Who are you? What does it mean to be a person in this world? What is reality? These are the questions Neuroscientist David Eagleman tackles in his new book, The Brain: The Story of You, and the PBS series, The Brain.

David Eagleman, used with permission
Source: David Eagleman, used with permission

Our common sense notion of reality is that our eyes, ears, nose, and fingertips pick up objective reality, but that couldn’t be farther from the truth. Smells, sounds, and colors do not actually exist in the outside world. The interaction between what’s “out there” and our sensory organs isn’t the whole picture, either. And the brain “has no direct access to the outside world. It’s locked in silence and darkness inside your skull,” says Eagleman. Our brains have never seen the outside world, and yet we experience it.

How? The slice of our ecosystem we can detect—or biological umwelt—is created by an interaction between the outside world, our sensory organs, and our “pink computational material.” But we go about our lives as though we are operating in an objective reality. “Each organism presumably assumes its umwelt to be the entire objective reality ‘out there,’” Eagleman writes in an article for The Edge. “Why would any of us stop to think that there is more beyond what we can sense?” Eagleman asks.

David Eagleman, used with permission
Source: David Eagleman, used with permission

And yet, with a little thinking we easily recognize that the reality we experience is constrained by our biology. For example, the umwelt in which bats exist is entirely different than the umwelt in which human beings exist—even when we are physically in the same space. While our reality is constrained by our sensory capabilities, the reality bats experience is constrained by their different sensory (sonar) capabilities. “Their brains are designed to correlate the outgoing impulses with the subsequent echoes, and the information thus acquired enables bats to make precise discriminations of distance, size, shape, motion, and texture comparable to those we make by vision," explains philosopher, Thomas Nagel. “But bat sonar, though clearly a form of perception, is not similar in its operation to any sense that we possess, and there is no reason to suppose that it is subjectively like anything we can experience or imagine.” The bat’s experience of reality has “a specific subjective character, which it is beyond our ability to conceive.”

In other words, our umwelt even constrains what we can imagine reality is like for a being with different sensorium, and, “our sensorium is enough to get by in our ecosystem, but it does not approximate the larger picture,” Eagleman asserts. On a deeper level, the complexity and speed with which the trillions of calculations are executed by each human being’s unique individual brain below the level of awareness is breathtaking. “Brains are as unique as snowflakes,” Eagleman declares.

So what can we know about the nature of reality? We must first confront our utter lack of in-the-moment awareness regarding how our umwelt shapes and constrains what we know as reality.

Michael May lost his sight at three years old from a chemical explosion. After years of blindness, his brain had developed the ability to operate without a sense of sight, but stem cell technology allowed him to undergo a procedure that reversed his blindness—sort of. May’s eyes can now see, but his brain still can’t. His reality now includes a confusing collection of visual images that he cannot correctly interpret. After 43 years of living in the "blind" reality his brain created, the visual stimuli aren’t interpreted by his brain in an intelligible way. The function of the brain, it turns out, is dependent upon input. So even years after his surgery, although he could “see,” his brain was unable to construct a visual reality that is subjectively like anything a fully-sighted person would recognize as reality. He told CBS news, “Vision isn't all that it's cracked up to be if — a big if — you have developed the other blindness skills to make you a fully actualized person.”

And May, Father of two, is fully actualized. The subject of Robert Kurson’s 2007 bestseller, "Crashing Through - A True Story of Risk, Adventure, and the Man Who Dared to See," May joined the CIA and became a successful inventor and entrepreneur while completely blind. (He is also a record-breaking Olympic blind skier.)

Just as May and other blind people are able to operate in a reality devoid of the light waves in the range received by the human eye, we are all able to operate in a reality devoid of the radio waves, microwaves, X-rays and gamma rays that are passing through our bodies all the time. We are unaware of them because we are “blind” to them—our sensory receptors are incapable of receiving them. And just as we have a direct perceptual experience of the things for which we do have sensory receptors, through Eagleman’s new sensory substitution technology, people without certain receptors—people who are deaf, for example—may be able to expand their umwelt to have a direct perceptual experience of sound waves without altering their existing sensory receptors.

How does the brain do that?

iStock Photo ©nimon_t
Source: iStock Photo ©nimon_t

The brain operates with electrochemical signals from which it extracts patterns and assigns meaning, creating your subjective world. But according to Eagleman, the brain doesn't know or care where the data comes from, it just figures out what to do with it, and it does it efficiently. Eagleman calls it “the P.H. model of evolution.” (P.H. stands for Potato Head.)

“I use this name to emphasize that all these sensors that we know and love, like our eyes and our ears and our fingertips, these are merely peripheral plug-and-play devices,” he told a TED audience in March, 2015. “You stick them in, and you're good to go. The brain figures out what to do with the data that comes in.”

And reality gets even harder to explain when we zoom out. Why are giggling and yawning contagious? Why does a person who is three degrees of separation from a happy person have an increased chance of being happy? Why do volunteering and donating money cause an increase in health and happiness? “Your neurons require other people's neurons to thrive and survive,” Eagleman says. “Who you are has everything to do with who we are.”

David Eagleman, used with permission
Source: David Eagleman, used with permission

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