Michael Graziano ’89 *96, an associate professor of psychology at Princeton, has proposed a new answer to an age-old question: What creates that sense of ourselves and the world around us that we call consciousness? His theory, which he lays out in a new book, Consciousness and the Social Brain (Oxford), surveys centuries of philosophy, psychology, and neuroscience. So it is disconcerting to hear him begin his explanation of consciousness by talking about a man with a squirrel in his head.
A psychologist friend, Graziano says, once had a patient who was convinced he had a squirrel trapped inside his head. Not a mental image of a squirrel but a real one, buck-toothed and bushy-tailed, scrambling around his cranium. The man was certain the squirrel was there, even though that defied all logic.
Likewise, Graziano argues, most of us believe that an ineffable thing called consciousness resides within us. We are sure of it. Great philosophers and scientists have tried to explain consciousness but ultimately fallen back on the conclusion that at some level, consciousness simply “is.” René Descartes believed our minds consisted of an ethereal substance he called res cogitans. Immanuel Kant posited that humans were born with thoughts and ideas that exist independently of all reason or experience. Francis Crick, the co-discoverer of DNA, thought consciousness was something that emerged from the electrical impulses generated by our neurons.
But Graziano argues that we no more possess an inner essence or emanation than his friend’s patient possessed a squirrel. That “spirit” we are so sure resides within us — which many of us think of as consciousness — is nothing more than a crude story we invent to describe a physical process taking place inside the brain.
This is not to call Michael Graziano dull or unimaginative. He is, in fact, a polymath who wrote his first symphony — 12 seconds long — at the age of 8, and a second, somewhat longer one at 13. He has since published five works for string quartets and six full symphonies; the fourth symphony, called “A Child’s Symphony,” contains that 12-second composition he wrote as a young boy. (Some of Graziano’s work can be heard at paw.princeton.edu.) Although one might guess that he most identifies with Mozart, perhaps the greatest prodigy of all time, Graziano says his musical idol is Beethoven, whose orchestrations he praises as “volcanically beyond common sense.”
He has written four novels under his own name on subjects ranging from science fiction to the last hours of a dying man, plus three novels for young readers under the pseudonym B.B. Wurge. His last children’s book, The Last Notebook of Leonardo, published in 2011, originated as a series of bedtime stories for Graziano’s now-7-year-old son, and tells of a mad-scientist father who turns himself into an orangutan and takes his son to the moon on a search for the last resting place of Leonardo da Vinci. Like all good children’s literature, there is a moral amid the fun:
“I hope you’re not going to turn me into anything,” the boy says when he first sees his orangutan-father.
“Don’t be silly,” the father replies. “I hope I’m turning you into a creative and imaginative person.”
Graziano himself grew into a creative and imaginative person in upstate New York, splitting his time between suburban Buffalo and a vacation home out in the country. His family did not have a TV, so he and his two sisters spent their time reading (Charles Dickens and James Joyce were favorite authors), writing, and making music. “We were very Robinson Crusoe,” he recalls.
He started studying piano at the age of 5 and became good enough that he considered playing professionally. As an undergraduate, he took all the courses required for a music major but majored in physics. Peter Westergaard, the William Shubael Conant Professor of Music emeritus, recalls Graziano as a student who understood tonal theory at an intellectual level and could apply it in his own compositions.
With many paths open to him, Graziano chose another passion — neuroscience — in part because it offered what seemed like an opportunity to achieve the career balance he wanted. “You could be a neuroscientist and still write symphonies in your spare time,” he explains. “You couldn’t be a composer and do neuroscience in your garage.” He also felt it was easier to do cutting-edge work in neuroscience than in physics, because less was known about it. “You can’t throw a stone without hitting a mystery,” he says.
Amid everything else he is doing (including serving on the PAW advisory board), Graziano has continued to dabble in physics as a hobby. His personal Web page contains two long, unpublished papers in which he imagines an alternate universe with special properties, and then spends a dozen or more pages exploring how physical laws such as quantum mechanics or special relativity would play out under those conditions. You know, for fun.
For roughly the first 10 years of his career, Graziano — shy, rumpled, and rather impish in person — produced groundbreaking work on how the brain understands and reacts to the space surrounding the body. He then spent a decade or so studying the ways in which the brain controls movement, proving that the classic movement map of the body — the so-called homunculus — is much more complex than originally thought.
Although Graziano might have devoted his career to either of these fields, in 2008 he decided to undertake a new inquiry, the study of consciousness. “The purpose of science isn’t to be an expert,” he says. “The purpose of science is to gain new insight.” When he begins to feel that his creativity in any area is waning and he is “not making contributions that are really insightful anymore ... that’s the point where I’ve got to get out.”
The question of consciousness and how it arises long had interested him, but as Graziano began scouring the voluminous academic and philosophical literature on the subject, he found himself dissatisfied. Over the past 20 or so years, two theories of consciousness have dominated. One, developed by Bernard Baars at the Neurosciences Institute in California, suggests that bits of pre-conscious information compete for access to a “global workspace” in the brain, which acts like a stage in a theater where conscious perceptions play out. The other, championed by Giulio Tononi of the University of Wisconsin and Nobel Prize winner Gerald Edelman, sees consciousness as a highly complex neural process that cannot be explained by referring to particular areas of the brain. Graziano felt that these and other theories got stuck at a certain point before declaring that consciousness just “happened,” that it was ultimately some sort of philosophical or physiological magic trick. His new theory “pulls the rug out” from under existing beliefs, says Aaron Schurger *09, a senior researcher at the Brain Mind Institute of the école Polytechnique Fédérale de Lausanne in Switzerland.
Graziano’s first attempt to articulate a new theory, a book published in 2010 called God, Soul, Mind, Brain: A Neuroscientist’s Reflections on the Spirit World, was aimed at the general public. When fellow neuroscientists pressed him to develop his ideas in a peer-reviewed journal, he obliged them, collaborating with his wife, Princeton psychology professor Sabine Kastner, on an article published in Cognitive Neuroscience in 2011. The new book, Consciousness and the Social Brain, followed in 2013; aimed at a lay and academic audience, it expands the theory and its underpinnings further.
Graziano calls his idea the “attention schema theory,” and it goes like this: Every living thing is constantly bombarded with stimuli — sights, sounds, and smells — and also, in humans at least, thoughts, memories, and ideas. The brain cannot process all of these stimuli at the same time, so it focuses its limited resources on some signals to the exclusion of others. This process is called attention: a method used by neurons in the brain to handle data.
Just as an architect uses models and blueprints to help understand the house she is building, the brain creates a model to help understand its own attention. Your brain not only creates models of the things you are attending to, it also creates a model of what it means to pay attention to them. This model, Graziano says, is awareness. To many neuroscientists, including Graziano, explaining awareness is tantamount to explaining consciousness, the total of the sensory information, ideas, memories, and sense of self you have in your mind. Once we understand how the brain can be aware of anything at all, we can begin to understand the full range of consciousness, he says.
Graziano’s attention schema theory breaks new ground by arguing that your awareness or consciousness of a thing — for example, a blue sky — is not some ethereal essence, but simply information encoded in the brain. As he explained last August in an article published in the online magazine Aeon, awareness “is not something magical that emerges from the functioning of the brain. When you look at the color blue, for example, your brain doesn’t generate a subjective experience of blue. Instead, it acts as a computational device. It computes a description, then attributes an experience of blue to itself. The process is all descriptions and conclusions and computations. Subjective experience, in the theory, is something like a myth that the brain tells itself. The brain insists that it has subjective experience because, when it accesses its inner data, it finds that information.” Because the brain is a data-processing device, in other words, it can access only information that is encoded within it, just as a computer’s hard drive can access only data written on the drive.
Futhermore, he continues, as this internal model of attention collates data from different domains, it “unlocks enormous potential for integrating information, for seeing larger patterns, and even for understanding the relationship between oneself and the outside world.”
Human brains are also very adept at attributing awareness and consciousness to others. You see that a woman is paying attention to her watch, and construct a mental model of her state of mind that says that she is aware of the time. This awareness can be a good way to predict what she is likely to do next; Graziano suggests that the process might have evolved hundreds of millions of years ago to help animals predict the behavior of other animals — useful for avoiding a predator, for example, or finding a mate.
Human beings even impute awareness to things they know aren’t alive. To illustrate this, Graziano begins many of his lectures by talking to an orangutan hand puppet he calls Kevin. Just a few minutes of their Edgar Bergen/Charlie McCarthy shtick serve to make his point. Of course we know that Kevin is not conscious, but we can’t help thinking that something inside the puppet is aware of itself and the world around it. In much the same way, we attribute awareness to nature or to things we cannot see, which, Graziano suggests, explains the belief in ghosts and in a god.
Where in the brain does all this activity occur? That is the subject of ongoing research, some of it done by Graziano and his research team in the newly completed Peretsman-Scully Hall on the south edge of campus. Two parts of the brain, however, appear to be critical as a way to compute awareness. One is the superior temporal sulcus, a part of the temporal lobe that is believed to help the brain follow another animal’s gaze or movement. The other is the temporoparietal junction, which is understood to help the brain reconstruct the state of mind of others.
Damage to these areas of the brain can badly damage a person’s sense of awareness, causing a condition called hemispatial neglect. A person with hemispatial neglect might have damage to the right side of the brain and lose awareness of everything on the left side of space. Ask him to draw a clock, and he will crowd all the numbers onto the right side of it, without recognizing he has ignored the left side. His brain is still paying attention, however, and if you throw a ball at his left side, he will flinch without knowing why. His brain has lost the ability to model attention in that area into consciousness.
Graziano and his assistants are now conducting a range of neurological experiments to test his theory. In one of them, they put subjects in an MRI scanner and ask them to look at a cartoon face and impute awareness to it. What is the cartoon face looking at? What is its state of mind? When a subject tries to answer these questions, the temporoparietal junction of her brain lights up. Researchers then zap the subject’s temporoparietal junction using trans-cranial magnet stimulations, a procedure in which a very strong magnetic field disrupts the activity of neurons for a fraction of a second. Graziano’s team has found that doing this disrupts the subject’s own sense of awareness, suggesting that the same part of the brain that enables us to impute awareness to others also enables us to impute it to ourselves. Graziano often volunteers himself as a guinea pig in his experiments, insisting that they are not dangerous and their neurological effects only temporary. Besides, he says, “it is good to make sure the equipment, instructions, and everything else works right.”
Graziano acknowledges that his theory may make people uncomfortable in its contention that consciousness is nothing more than a model of attention. After all, people believe in souls and spirits. But he writes that many of our superstitions “emerge naturally from the simplifications and shortcuts the brain takes when representing itself and its world.” His article in Aeon drew about 400 comments on topics spanning from philosophy to God to zombie thought experiments. The theory has been discussed on psychology and philosophy blogs, with strong, though mixed, reactions.
If the brain is just a data-processing machine, then Graziano sees no reason we cannot create computers that are just as conscious as we are. It will require three things: First, the computer must be able to sort information and control its actions the way the brain processes attention. Second, it must be able to create models that track, simulate, and predict patterns of attention in itself and in other things. Finally, it must be able to link its attention schema to information about itself and those other things. Graziano believes that a team of talented programmers with enough funding could do this in about a decade.
Although he is an atheist, Graziano accepts that a sort of afterlife does exist in the imperfect models of our personalities that live on in the minds of those who knew us. But he considers it a “technological inevitability” that a computer-generated afterlife someday will be possible as well, as technology enables us to copy the information in our conscious minds and store it after we are gone. “Don’t want to die?” he asks. “Download your consciousness onto a central server and live in a simulated world with all the other downloaded souls. When your body dies, a copy of your mind will persist.”
Such a future may sound bleak, but take comfort. A neuroscientist who writes children’s books and composes symphonies is enough of a humanist that he would not leave us completely bereft. Our ability to impute awareness to ourselves, he believes, is the first step toward imputing it to others, and that is what has enabled us to become successful social beings. Intuiting what takes place in other people’s minds, he writes, “allows us to work together: It gives us our culture and meaning, and makes us successful as a species. We are not, despite certain appearances, trapped alone inside our own heads.”
Mark F. Bernstein ’83 is PAW’s senior writer.