The Ravenous Brain: How the New Science of Consciousness Explains Our Insatiable Search for Meaning

by Bor, Daniel

  Two questions concerning our inner mental life have, for centuries, obsessed philosophers: (1) Why is consciousness inherently subjective? and (2) How can a physical lump of matter give rise to the glorious variety of sensations we can experience, from seeing a red rose to hearing a Beethoven symphony? Tononi ambitiously claims to be able to address both of these issues.

  For Tononi, the inherent subjectivity of awareness, where my experiences are private to me alone, impenetrable to anyone else, is an essential component of consciousness, because that is precisely what the mathematics of his theory predict. If consciousness is just the activity in the densest part of the network of my brain, how could my consciousness extend outside my brain—for instance, to another person? There are no network connections to make this possible, for a start. But even if these connections somehow were present—for instance, I had some sort of neural graft connecting my brain with another’s—if this connection was too weak, then there would be two dense networks and two consciousnesses, with a very weak experiential connection between the two. This situation would be broadly similar to that of the conjoined twins Tatiana and Krista, who are very much two different people, but who just happen to share the occasional feeling. So subjectivity, far from a philosophical conundrum, might simply be a product of the way that closed networks generate their compound, unified items of information—a mathematical, computational process that we happen to call consciousness.

  And what imbues my awareness with all the different sensations that I can experience? Why do my baby daughter’s dark brown eyes appear that particular color to me? Why does her sweet, high babbling voice have that precise sound? And why does my stroking her soft cheek as I send her to a night of sleep have that particular feel? According to Tononi, whatever we experience is permeated by its specific sensation because of the precise point it takes up in this huge space of possible forms of combined information we can represent. The dark brown shade of my daughter’s eyes feels like it does because of the informational contrast it makes with all the other colors I could possibly see, which evoke similar experiences for their similar informational content. But that particular experience of color is also in contrast to all the other experiences I could have in my other senses and beyond, which feel less similar because of their greater informational distance. So every experience we could possibly have, as a unique set of pooled information, gets its distinct perceptual characteristics from its relationship to all our other possible experiences.

  Some might argue that these bold claims for consciousness are similar in validity—or lack of it—to any opposing philosophical claim. I think Tononi himself would be the first to admit that his theory, mathematically dense though it is, currently exists only as a skeleton of a framework for consciousness. And there are rather strange corollaries of the information integration theory in its present form that sit rather uneasily with much of neuroscientific data. For instance, the theory doesn’t in any way equate a heightened neural activity to increased consciousness, so from the perspective of the theory, a quiescent brain is just as likely to produce a highly conscious state. This clashes with virtually all the studies I’ve discussed throughout this chapter. Moreover, there is no distinction in information integration theory between useless, unpatterned forms of information and highly structured, profound chunks of insight, which I’ve repeatedly argued are really the hallmarks of consciousness.

  But what Tononi has done, quite differently from the philosophers, is to provide a very brave, thought-provoking first sketch by which to explore deep questions about awareness in a scientific way. Because information integration theory allows you to compute a single number for just how much consciousness at a given time resides in an animal (or robot, for that matter), based on its network architecture and changing states, many opportunities for exciting experiments immediately arise. In practice, though, in the present form of the theory, this “consciousness number” carries too great a calculation burden for today’s most advanced computers, even for simple simulations of animals with only a handful of neurons. So there are, at present, severe practical limitations to information integration theory (although I will be discussing in future chapters the methods scientists are using to make useful approximations to this magic number).

  In fact, a common drawback of all the neural theories of consciousness, one way or another, is that they tend to focus on mathematical or neurophysiological details while somewhat neglecting the psychological components that make up consciousness. In my view, the next iteration of these models will need to place attention as a key ingredient in the recipe for consciousness, rather than assume it is a separate process, as many scientists currently seem to do. And if they include working memory at all (at present only the global neuronal workspace theory does), then they should flesh out the details of this—such as including chunking processes as a fundamental component and explaining just how our consciousness is so ripe for innovative thoughts.

  Ultimately, the test of these models will be whether they can predict a surprising psychological feature of consciousness, as well as its corresponding neural details, that we can then confirm in a future experiment. This current set of theories, despite their great promise and encouraging convergence, are a few stages removed from this predictive level as yet.

  EXPLAINING EXPERIENCES

  Even if there are still small but significant gaps in consciousness research and theory, nevertheless an exciting picture is emerging. This perspective, for the first time, provides a coherent explanation for the evolutionary origins and purpose of consciousness, as well as the mental architecture and neural underpinnings of our experiences.

  We all have learned at school that for life to exist you need a suite of certain chemicals, measured out in the right proportions—water, carbon, and so on. And such ingredients are indeed essential. But what is far more fundamental—what matters, above all—is that in this blind struggle for survival and reproduction, in this delicate dance between genes and the environment, there is a pressure to gather information. All organisms are biological computers, forging a successful niche in the world by iteratively gathering a specific bank of useful, implicit knowledge. All successful life, via the ideas stored in its DNA, shapes itself to the relevant features of the world.

  But animals, additionally, can learn more dynamically. They can gather vital new facts to help them survive and adapt, not just between generations, but within their own lifetimes. At birth, we humans are terribly vulnerable, with few instincts and poor senses, but with a mind wide open. In our lifetimes, we absorb a staggering quantity and variety of information. Although simple features of the world can be detected below our conscious radar, we funnel the most useful, novel, and complex information, via attention, into the tightly limited, but also unimaginably flexible, workspace of our conscious minds. In this playground of possible experiences and ideas, we spot insights, we see the hidden regularities in the world, and, in so doing, we understand and comprehensively conquer the planet. It is our consciousness that is responsible for this—a consciousness that builds pyramids of information that we readily retrieve and manipulate. Our brains are exquisitely, densely wired so that information can easily flow from specialist regions, which store our refined gems of knowledge, into other areas that have no specific role themselves, but are so thickly connected with the rest of the brain that information, probably via high-frequency waves of neural activity, can easily flow and combine. Here, in the intensive neuronal murmuring of the thalamus and prefrontal parietal network, we do so much more than link raw redness with a simple shape; we experience the sight of a vivid crimson rose, we smell its soft aroma, and connect it with the exciting new romantic flame we just handed it to, as we anticipate many future experiences to share with her.

  Now, with the psychological and neural features of consciousness fleshed out, I’ll turn to how this picture of our experiences can be applied, first to assessing awareness in those beings that lack the language to t
ell us. I will then turn to the clinical implications of this new scientific view of our experiences.

  6

  Being Bird-Brained Is Not an Insult

  Uncovering Alien Consciousness

  TENDER CHIMPS, CAPRICIOUS BONOBOS

  Monkey World, in Dorset, England, is the largest primate rescue center in the world. Although it looks after orangutans, gibbons, monkeys, and lemurs, primarily the center houses chimpanzees, with the highest number in any one place outside of Africa, currently about sixty strong. This group of chimps, largely saved from neglect or abuse, is cared for by thoughtful, devoted staff, and the animals seem to lead a relatively happy, natural life. Monkey World is such a popular location that multiple television documentary series have been made describing the fascinating activities at the center. The following story is taken from one episode.

  Some years back, Olympia, like all female chimps in the center, was given a birth control implant, but managed somehow to remove it, and promptly became pregnant. She was a devoted mother for a year to her daughter, Hebe, but then her milk dried up. The Monkey World staff made the difficult decision to remove Hebe from her mother for a while so that a human could continue to feed her. Six weeks later, they started reintroducing Hebe to her mother in short visits, with a view eventually to returning Hebe to Olympia full time, when food was no longer an issue. Jim and Alison Cronin, the husband-and-wife team in charge of Monkey World at the time (sadly, Jim Cronin has since died), were concerned about how the mother and daughter would react, so decided to take very tentative steps toward a reunion. Their most experienced primate manager, Jeremy Keeling, moved into a special nursery room with Hebe, who was clutching tightly to Jeremy with all four limbs when her mother, Olympia, was brought in.

  Olympia clung impatiently to the bars of the door, knowing her daughter was on the other side. As soon as the door swung open, Olympia walked in and maneuvered herself to be ready to take Hebe off her human caregiver, Jeremy, and excitedly give her a hug. But Hebe wasn’t so sure who this adult chimp was and became distressed, clinging ever more tightly to Jeremy. Olympia didn’t get frustrated, though. Instead, she tried to innovate. She played it cool. She walked away and started to make a nice inviting, cozy nest out of the straw in the far corner of the room. Hebe slowly realized that this big chimp wasn’t a threat and maybe, possibly, was someone special in her life. She left Jeremy’s safe human hands and walked a few steps toward the nest and her mother’s arms. But as Olympia gently approached, Hebe had second thoughts, backing up again toward Jeremy.

  So Olympia tried another tack: Hebe and Jeremy were sitting on a table, so Olympia waited under it and held out her arms invitingly, ready to catch Hebe if she fancied a fun jump toward her. Hebe still wasn’t convinced. The next strategy was for Olympia to pretend to ignore Hebe and instead groom Jeremy, picking intently at his thick moustache. Finally, Hebe was relaxed enough to allow her mother gently to touch her arm. Carefully Olympia looked all over Hebe’s body, as if to check that she was all right. Progress—but still not the hug between mother and baby that Olympia sorely wanted. So Olympia tried one last thing: She pretended to leave. She walked out of the room, opened a metal cage door, and shut it again from the other side, all the time watching her baby. This—almost—had the desired effect. Hebe left Jeremy and rapidly approached the door and her mother, as if she didn’t want her to go. Olympia quickly opened the door and held out her arms for a hug, but Hebe’s nerves returned, and she rushed back to Jeremy. The staff called it a day for this first attempt, and they left a distressed mother to ponder things over with her main group, which soon came to join her. The next attempt, a day or two later, was far more successful.

  It’s possible that everything that happened in the above scene was behavior with no conscious life at all. It’s also possible that every thought and feeling we project onto these chimps is real—that a mother, who deeply missed and loved her daughter, calmly understood that this daughter no longer recognized her. So she put herself firmly inside the mind of her young, frightened child and tried anything she could think of tenderly to calm the baby and once again make her embracing arms an inviting presence.

  Bonobos, a very close relative of chimpanzees, and at least as intelligent, also exhibit behaviors that appear to reflect a burgeoning consciousness highly comparable to our own. Sue Savage-Rumbaugh, who investigates the extent to which bonobos can learn language, in her book Kanzi, coauthored with Roger Lewin, recalled the following story about a mature female bonobo named Matata:Once, when I was introducing a new person to Matata, she became jealous of the new person and refused to let her touch any item that she was fond of, including her blankets, her bowls, her food, and her mirror. One day we were sitting together on the floor when Matata decided to ask me to go get some food by holding her empty bowl out to me and making a food sound. I told Matata I would get her some food and left the room, leaving the bowl with her. I had been gone less than five minutes when suddenly Matata began screaming loudly. When I rushed back into the room the new person was holding Matata’s bowl and Matata was screaming at her and threatening to bite. Matata looked back and forth from me to this person and then to the bowl, screaming—intimating that the bowl had been grabbed from her in my absence and that I should support her in attacking this mean individual who had taken her bowl. Of course, given the gift of language, this person was able to explain that she had indeed done nothing. Matata had placed the bowl in her hands and then started screaming for me as if she had been wronged.

  When Matata saw us talking about what had happened, she began to look very crestfallen, concluding her ruse had not worked. She stopped screaming and moved to the corner where she suddenly became very preoccupied with grooming herself.

  The above two examples, at opposite poles of complex behavior—one tender, the other capricious and possessive—provide tantalizing anecdotal evidence that there are nonhuman species that lead a complex conscious life not that dissimilar from our own. But how can we establish that this is true in our closest evolutionary cousins, let alone in far simpler or more alien creatures?

  In this chapter I’ll be describing how we can make headway in assessing consciousness in all these nonlinguistic beings, with animals as the main model. I will also discuss the common intuition that even if other animals are conscious, there is something quite special and unique about the kind of awareness that humans possess.

  I will be outlining two main angles of attack here: First, an analysis of those forms of animal behavior that seem most redolent of consciousness, if the same behavior were seen in humans; and second, what types of brain structures and functions are the most suggestive of consciousness in any life-form.

  CRAFTY CROWS

  But how does one go about assessing whether pigs, for instance, are conscious. Outward signs that they are in distress—squealing when they are in pain—might be a hint that they are aware. But a skeptic will claim that this could purely be a behavioral response, that the animal was programmed to make that noise when it had a certain pressure applied to its skin, but that there is not necessarily any conscious life in between the pressure and the squealing. The obvious yet important fact that animals can’t use language to tell us whether they are aware means that, technically, the skeptic’s position is an entirely valid one.

  A slightly more suggestive feature of animal behavior than suffering, often overlooked in discussions of the extent of their awareness, is that many animals appear to get bored. Humans may well be ravenous for information, but many other species, too, seem to have a hunger for knowledge that they critically need to meet. If you place animals in a drab lab cage, a dark, simple farm pen, or a zoo enclosure with no objects with which to interact, many of them will soon develop stress behaviors. They will pace up and down, rock back and forth, or simply start to appear apathetic, spending much of the day sleeping and resting. If left for long enough, many animals show signs reminiscent of human self-harm or outright mental illness: A parrot
may peck off all its feathers, a rat may nibble off the ears of its offspring, monkeys may try to gnaw off their own limbs. These signs of abuse can be at least as disturbing as if the animal were regularly beaten.

  The extent of suffering in these cases is particularly tendentious, since it arises out of a poverty of intellectual stimulation. But perhaps more direct evidence of animal consciousness can come from the extent of animal intelligence. Here, we needn’t necessarily look to obvious examples like our great ape cousins to see signs of impressive mental capabilities. Nicky Clayton has devoted her career to studying corvids, a bird family including crows, ravens, jays, and magpies. Along with parrots, they are effectively the geniuses of the bird world, with large brains for their body size. A corvid has about the same brain-to-body ratio as a chimpanzee, even if the actual volume of its brain is only about the size of a walnut. These bird Einsteins lead complex social lives, with a strict social hierarchy, and even participate in social play.

  Clayton’s work has used these birds’ propensity to hide their food for future consumption as a means to study their mental lives in many different ways. It’s already well known that at least some corvids have an excellent memory, since they can recall the locations of hundreds of food items they have stored over previous months. But Clayton, along with her colleagues, has also shown that these birds plan for the future. For instance, scrub-jays, like us, enjoy a varied diet. If they know that their experimenter will only give them one kind of food the next morning, then the night before they will store a different kind in that location, thus ensuring, 12 hours later, that they have a choice for breakfast. Clayton has even demonstrated that they seem to have a clear mental understanding of the thoughts of competing birds. For instance, scrub jays will, if given the chance, watch where another bird has stored some food, and steal it away when the bird isn’t looking. But if a scrub jay notices it is being watched by a potential bird thief, then it will furiously re-hide the food to fool the observer. You might think this is just an instinct. It isn’t—a scrub jay will only attempt to re-hide food when observed if it has already learned how to thieve from other birds, and it will not re-hide it if observed by its mate. It’s tempting to explain this attempt at disguising the food locations purely in terms of a sequence of clearly conscious thoughts that the jay could be having: First he discovers a wonderful extra source of food from exploiting all the hard work of another jay and stealing her stash; then he realizes that if he can steal a neighbor’s bank of grubs, then so can any other jay; and finally, when he spots a potential thief, he imagines she could be harboring similarly thieving thoughts, and so he devises a strategy to confuse her.