BUBBLING BROOKS AND PERSONAL CONSCIOUSNESS
“It would be so nice if something made sense for a change.”
—Alice, in Lewis Carroll’s Alice’s Adventures in Wonderland
WE ALL SHARE this state we call consciousness, this awareness of our streaming thoughts, longings, emotions, and feelings about the world, others, and ourselves. It is not only omnipresent but personal, defining, and boundary setting. It defines the experience of living. The conscious self seems to ride above the physical brain and all its layers and modules. It seems that without it, we would be nothing but one of the automatons that Descartes observed in the gardens of Paris. A machine. So what would an explanation for consciousness possibly look like?
As you might guess, the elements of the puzzle that I think can lead us to some new thinking about the nature of conscious experience are the things we’ve covered in the preceding chapters: modules, layers, the principle of complementarity, and Howard Pattee’s semiotic closure. These concepts will help us see how neural circuits are structures with a double life: they carry symbolic information, which is subject to arbitrary rules, yet they possess a material structure that is subject to the laws of physics. Combined, these perspectives tell the story of the brain. It is an organ, finely engineered by natural selection, organized into local modules whose functioning is accomplished in a layered architecture such that, for the most part, one set of modules doesn’t know what all the others are doing. It is the story about how a bunch of hardworking small circuits exist in a coherent organization to produce a larger function, just as citizens, smart as they are, work in relative isolation to produce something like a society. The secret to understanding must include how the hardworking parts express themselves, moment to moment.
If gaps, modules, and layers are to help us understand how brains make minds, they must also account for some persistent facts about brains. Take a moment to fully consider this and its ramifications for your sense of self: a neurosurgeon can disconnect the two hemispheres of your brain and produce two minds in your single head—two minds with different contents at the same time, though with the same emotional drives and feelings. Next, remember: while brain damage can cause specific deficits, it is almost impossible to eliminate consciousness completely. And finally: while conscious experience seems unified and whole, it happens in concert, with multiple systems running parallel to one another, each separately spewing forth the results of its processing. Thus, while consciousness seems to be a cogently coherent, flawlessly edited film, it is instead a stream of single vignettes that surface like bubbles roiling up in a boiling pot of water, linked together by their occurrence through time. Consciousness is in constant change, a stream, and, as William James once said, “No state once gone can recur and be identical with what it was before.”1 Let me set the stage for this idea.
Two Consciously Different Conscious Hemispheres!
I have to go back again to the very first scientific observation I ever made. It was on Case W.J., a man who had such severe epileptic seizures that he was only able to function normally about two days a week. A young neurosurgeon, Joseph Bogen, had done some extensive research and suggested that W.J. might benefit from a rarely performed surgery in which the large tract of nerves that connects the two cerebral hemispheres was cut. It had been done on a series of patients in Rochester, New York, twenty years earlier to control epilepsy. The surgery was successful in stopping or drastically reducing the seizures. Oddly, after having their brains cut in half, all those patients said they felt fine, and the only difference they noted was the loss of seizures.
W.J. was a World War II veteran and had fought many a battle. He weighed the odds of this one and agreed to the surgery. I was the young graduate student who had designed tests to run after he had undergone split-brain surgery to see what, if any, effects this surgery had wrought on his brain function. The expectation was that there would be none, since none had been found in the Rochester patients. W.J. was a warm, affable man, and the two hemispheres of his brain seemed to be working fine together, although they were no longer in direct communication. One of them talked, one of them didn’t. Given the way the brain is wired, that meant the left, talking brain viewed the visual world to the right of a fixated point and the right, non-talking hemisphere viewed all the visual information to the left of the same point. Given this surgical state, I wondered: If I flashed a light over to the right, would W.J. say he saw it? Light should go to the left hemisphere, and the left hemisphere had speech; it should be easy. It was, and W.J. easily declared he saw it.
A bit later, I flashed the same light over to the left side of space and waited to see if he would say anything. He didn’t. I pressed him and asked if he had seen anything, and he firmly said “No.” Was he blind on that side? Or was that simple spot of light no longer communicated to the half brain that talked? Did the seemingly mute right brain know it had viewed a light? Was it conscious? What was going on?
It was later in that testing session that it became clear that the mute right hemisphere had indeed spotted the light, because the right hemisphere could easily and accurately point to it with W.J.’s left hand. It was the beginning observation that revealed that not only the brain but also the mind had been divided. It was the seed that led to sixty years of research on the nature of mind and its physical underpinnings. It was also the test that produced the most astounding observation of all. The left, talking brain didn’t seem to miss the right brain, and vice versa. It didn’t just not miss it—it didn’t even remember it or the functions it had performed, as if the right hemisphere had never existed. For me, this phenomenon is the single most important fact students of mind/brain research must take into account.
How come the left brain doesn’t complain about the fact that it is no longer conscious of things on the left side of space? Imagine having your brain disconnected. Imagine waking up in your hospital room the next morning and, as your surgeon walks in to see how you are faring, you only see the left half of her face. Don’t you think you would notice that the right half is not there? The thing is, you would not. In fact, your left hemisphere wouldn’t even be conscious of the fact that there is a left half of space. But this is the weird part: I spoke as if the new, split version of you were just your left hemisphere, and that is not true. You are also your right hemisphere. The new “yous” have two minds with two completely separate pools of perceptual and cognitive information. It is just that only one of the minds can readily speak. The other initially cannot. Perhaps, after many years, it will be able to produce a few words.
More crazy yet, in the early months after surgery, before the two hemispheres get used to sharing a single body, one can observe them in a tug-of-war. For example, there is a simple task in which one must arrange a small set of colored blocks to match a pattern shown on a card. The right hemisphere contains visuomotor specializations that make this task a walk in the park for the left hand. The left hemisphere, on the other hand, is incompetent for such a task. When a patient whose brain has recently been split attempts the task, the left hand immediately solves the puzzle; but when the right hand tries to attempt the task, the left hand starts to mess up the right hand’s work, trying to horn in and complete the task. In one such test, we had to have the patient sit on his bossy left hand to allow the right to attempt the task, which it never could accomplish! It was beyond the capabilities of the left hemisphere.
When communication between the hemispheres is lost, each is unaware of the other’s knowledge and each functions independently based on the information it receives. Both sides of the brain try to complete the task independently, resulting in the tug-of-war. By this simple task, the illusion of a unified consciousness is exposed. Clearly, if consciousness arose from a single location, then a split-brain patient would be unable to have two simultaneous experiences!
It gets better. We have all seen the film of the simple illusion that occurs when two balls seemingly hit each other, and, after the faux collision, the supposedly impacted ball takes off. In psychological parlance this is called the Michotte launching effect, after the Belgian psychologist Albert Michotte, who first invented the illusion to investigate how we perceive and infer causality. Since the first ball stopped next to the second ball and didn’t actually hit it, there is in fact no physical event that happened to cause the second ball to take off. But that is not how we all view the experience. Ball A hit ball B and it took off, period. There was causality!
So how do split-brain patients view this simple task? Does the left brain, with the flavor of consciousness it possesses, see it the same way the right hemisphere might see it? An experiment to test this was first initiated by Matthew Roser, originally a student from New Zealand, who was then in my laboratory at Dartmouth and is now residing at Plymouth University in England.2 An exceptionally talented scientist, Matt, along with other colleagues, examined how each half brain, working alone and disconnected from the other, viewed the seemingly colliding balls. The results were astonishing. The right hemisphere instantly grasped the illusion, while the left brain did not. This was established by a second experiment, in which the distance between the balls at the point of the faux collision was slightly increased, or the amount of time it took for the second ball to move was increased. In these circumstances, the illusion disappears for the right hemisphere and never occurs. The left brain, the one that does the heavy lifting on all matters cognitive, simply didn’t ever see through the illusion under any conditions. Interestingly, the left brain does see relationships that the right seems unable to grasp. In the context of these tests, it was the left brain that picked up on another problem, requiring logical inference, which the right brain was unable to do. In short, the direct perception of causality was something the right hemisphere could do, but the ability to infer causality was only in the left hemisphere’s bag of tricks.
When we consider how the normally connected brain perceives these two kinds of tasks, it suddenly becomes clear that when seeing the illusion, it is the right hemisphere that has the neural equipment to apprehend it. And, when tackling a logical inference task, it is the left hemisphere that is processing the information. So, in a connected brain, at time A, when the right hemisphere is seeing a launching ball test it is saying “Hey, ball A just hit ball B,” but at time B, when it is looking at a logical inference kind of test it is the left hemisphere, not the right, that is able to apprehend it. It is kind of like the arcade game Whac-a-Mole. We are aware, which is to say conscious, of the processed information as it pops up after being processed in a particular hemisphere. But is that because each neural process activates a “make-it-conscious network” (which would have to be present in each hemisphere), or does each process in and of itself possess the neural capacity to appear conscious?
Tiny Bubbles
I am in the latter camp. Thinking about this question led me to use the metaphor of bubbling water as a way to conceptualize how our consciousness unfolds. Consciousness is not the product of a special network that enables all of our mental events to be conscious. Instead, each mental event is managed by brain modules that possess the capacity to make us conscious of the results of their processing. The results bubble up from various modules like bubbles in a boiling pot of water. Bubble after bubble, each the end result of a module’s or a group of modules’ processing, pops up and bursts forth for a moment, only to be replaced by others in a constant dynamic motion. Those single bursts of processing parade one after another, seamlessly linked by time. (This metaphor is limited to bubbles roiling up at a rate of twelve frames a second or faster; or consider a cartoon flip book, where the faster we snap the pages, the more continuous the movements of the characters appear.)
Sir Charles Sherrington, the doyen of modern neuroscience, had a related notion when he observed:
How far is the mind a collection of quasi-independent perceptual minds integrated psychically in large measure by temporal concurrence of experience? Its separate reserves of sub-perceptual and perceptual brain, if we may so speak, could account for the slightness of the mental impairment following on some brain injuries.… Simple contemporaneity can conjoin much.3
It’s difficult to get our heads around the idea that each bubble has its own capacity to evoke that feeling of being conscious; it rubs up against our own intuitions about the holistic nature of our personal consciousness. What are we and our intuitions missing? We are missing the illusion part, the part we humans (with our powerful left hemisphere inference mechanism) are so good at missing. We aren’t actually missing the illusion; rather, we are missing the fact that our smoothly flowing consciousness is itself an illusion. In reality it is made up of cognitive bubbles linked with subcortical “feeling” bubbles, stitched together by our brain in time.
Background for Bubbles
There is a classic observation that rings true across all of biology. The observation concerns whether organisms learn and take instruction from the environment or whether the reactions that organisms have to environmental stimuli are managed by systems already built into the organism. The “selection versus instruction” debate has raged for years and has especially caught the limelight in the field of immunology. Put simply, when something foreign enters the body and there is an immune response to it, are the antibodies formed then and there around the foreign body, and do they then multiply (instruction)? Or does the antibody already exist, and is the immune response time the time it takes to find the preexisting antibody (selection) and jerk it into action? In the previous century, biology learned it is the latter situation, a finding that illustrates that a whole lot of stuff comes with the package—standard equipment for our bodies and brains.
Niels Jerne, the Danish immunologist, proposed in 1967 something rather startling at the time: what is true for the immune system is probably also true for the brain. He suggested that preexisting circuits in the brain are selected by the environment and are applied during what we might think is a “learning” situation.4 With this strong naturalistic view, learning is simply the time it takes for the brain to sort through its gazillion circuits to find the one more appropriate for the challenge at hand.
While this crucial debate rages on, no one would doubt that there are neural circuits for specific functions that come as “standard equipment” with our brains. For example, babies as young as six months have demonstrated that they already possess the ability to make causal inferences.5 And subcortical circuits make their processing apparent as soon as that newborn cries for its first meal. In the bubble metaphor, bubbles are the end result of the processing of those circuits that are constantly in play to cope with and manage the endless challenges of the environment. Those processes are both cortical and subcortical. Let’s look at another telling experiment before we get to the subcortical bubbles.
Bats in the Belfry
For better or for worse, Thomas Nagel’s infamous question “What is it like to be a bat?”6 has stirred the philosophically minded for forty years. Actually, the question should be “What kind of bubbles does a bat have?” That is, what are the contents of a bat’s consciousness? We will probably never fully experience bat-brand consciousness, but we can observe the contents of a lonely single hemisphere in a human brain. The brain is full of bubbles, and when a brain is split, each half has its own set of bubbles that boil up. Since we now know that each half brain has some unique bubbles, might it be that each hemisphere harbors a different kind of overall conscious experience? To get a feel for this, consider what bubbles you don’t have. For instance, I can tell you I don’t have the abstract math bubble; therefore, I can tell you I feel frustrated when equations start popping up in lectures. Though I wish I could, I cannot tell you what it is like to grasp highly abstract math, but I bet it would be cool!
Rebecca Saxe, at MIT, has discovered in some intriguing studies that there is special human brain hardware in the right half brain that appears specialized for determining what the intentions of another person might be.7 When we interact with others, we are constantly and reflexively making assessments of their mental state and their intent in all of their actions. It is virtually automatic. It appears that children with autism lack this capacity to a large extent and, as a result, find social interactions difficult. As I discussed earlier, in formal psychological parlance it is called having a theory of mind. Saxe, using modern brain imaging techniques, discovered a brain area in the right hemisphere responsible for this capacity. As you might guess, this observation raises a new question. The Saxe finding would suggest that perhaps the left hemispheres of split-brain patients may not have access to the module that adds theory of mind to our cognition. What would a left hemisphere be like that didn’t have access to that capacity?
Michael Miller, my former student and now colleague, and Walter Sinnott-Armstrong, the distinguished philosopher, teamed up to examine the implications of the Saxe finding for split-brain patients.8 They wanted to determine if one separated hemisphere might evaluate moral issues differently than the other. Again, in a split-brain human, Saxe’s work suggests one hemisphere (the right) would have the module that considers the mind and intentions of others, while the other hemisphere (the left) would not. Upon separation, would the left hemisphere act differently, since it no longer possessed a module that evaluated the mental states and intentions of others?
Moral philosophers like to approach moral dilemmas as having either a deontological or a utilitarian nature. In plain English that means, “Do we solve the dilemma by considering what is inherently right, what our moral duty is, or does the solution reside in maximizing collective good?” There are many ways of phrasing this dichotomy and many ways to reveal whether someone is more deontological in their thinking or more utilitarian. In a series of cleverly devised tests, patients were told stories in which the main person did something evil but the outcome was, nonetheless, un-harmful: If a secretary wants to bump off her boss and intends to add poison to his coffee, but unknown to her, it actually is sugar, he drinks it, and he is fine, was that permissible? Or the story was about a person doing something that seemed innocent to them but proved to be fatal to someone else: If a secretary believes that she is adding sugar to her boss’s coffee, but it actually is poison accidentally left there by a chemist, and her boss drinks it and dies, was that a permissible action? The patient, upon hearing the full stories, had to simply judge whether the act the person did was “permissible” or “forbidden.”
Needless to say, most people judge an example with mal-intent as forbidden no matter what the outcome. Most people in this sense are deontological. Most people would judge an action by someone who had no malicious intentions to be permissible (although not always), even though it sometimes can end in tragedy. Split-brain patients act in a unique way. It appeared the left, speaking hemisphere initially offered a utilitarian response to all scenarios. Thus, if an act had mal-intent but no harm came from it, it was judged as “permissible.” And if an act did not have mal-intent, but resulted in harm, it was judged “forbidden.” Given the clarity of the stories used, this was a jarring result. What is going on? The disconnected left hemisphere is unable to take into account the intent of the person in the stories, acting as if it didn’t have a theory of mind.
Second, the patients would then frequently give spontaneous explanations as to why they had chosen the utilitarian result over the clearly deontological choice. It seemed they “felt” their judgments were not exactly copacetic, and they often rationalized their judgment without any prompting. Remember, the left hemisphere does have its interpreter, the module that tries to explain both the behavior it observes pouring out of the body and the emotions it feels. Keep in mind that an emotional reaction to something experienced by one side of the brain is felt by both. If the emotion was a result of the right brain’s experience, the left brain has no information about why it is feeling the emotion it is, but explains it anyway. So, when the right brain heard the left brain’s answer (even with limited language abilities there is still some comprehension in the right hemisphere), it was just as shocked as we were, resulting in an emotional reaction that didn’t match what the left hemisphere considered to be a reasonable answer. With the stage set for a major conflict like this, it was not surprising that the special module in the left hemisphere (the “interpreter” module—the one that is ever ready to explain away behaviors produced from the silent disconnected right hemisphere) jumped in and tried to explain what was going on. For example, in one scenario a waitress served sesame seeds to a customer while falsely believing that the seeds would cause a harmful allergic reaction. Patient J.W. judged the waitress’s action “permissible.” After a few moments, he spontaneously offered, “Sesame seeds are tiny little things. They don’t hurt nobody.”
In my metaphor, a bubble is the end result of the processing of a module or group of modules in a layered architecture. The special module that evaluates the intent of others in split-brain patients is disconnected and isolated from the speaking left hemisphere. As a consequence, the result of its processing doesn’t bubble up to contribute to or battle for dominance in the left hemisphere’s decision-making process. It can’t be part of that bubbling process if it is not physically located in the left hemisphere among the bubbles having access to language and speech. So, eerily, the knowledge of the intent of the other is absent. Yet bubbles from midbrain emotional processing do make it to both hemispheres. It is only when the right hemisphere hears the left hemisphere’s response, resulting in an emotional feeling felt by both hemispheres, that a mismatch is identified by the left hemisphere. That sets the process of justification in motion. The left hemisphere also has a lifetime of memories stored about the moral norms of the culture it has grown up in and can use these for justifications.
We are discovering that the subtleties of our psychological lives are being managed by specific modules in our brains. Again, the left brain, which benefits from modules that enable abstract thinking, verbal coding, and much more, does not have the module to take into account the intentions of others. Yet it has a powerful inference ability. If the result is good, it infers the means were okay. Thus, if the result is fine, the act is permissible. If the end is bad, the act is not permissible. What is the best for the most is okay. The uncanny and almost surreal aspect of these findings is the possibility that if the proper module that enables one to think about others is missing, one can’t seem to learn it.
What Is It Like to Be a Right Hemisphere?
What if you suddenly lost your left hemisphere? What would your conscious experience be? Remember that you will not actually notice that anything is different, because you will not miss the left hemisphere’s modules. Really. Having lost the speech center, communication and comprehension abilities would take a nosedive. The right hemisphere would only be able to manage limited comprehension and vocabulary. But one of the biggest contributors to a changed experience would be the loss of your ability to make inferences. You constantly use this left-hemisphere ability, and lacking it would plop you into a very different experience of the world. Though you would know that others had intentions, beliefs, and desires, and you could attempt to guess what they might be, you would not be able to infer cause and effect. You would not be able to infer why someone is angry or believes as they do. Many of your social encounters will probably result in misunderstandings and frustration on both sides. But the loss of your inference ability is not limited to the social world. You would not infer causality at all. Not only do you not infer that your neighbor is angry because you left the gate open and her dog got out, you don’t infer that the dog got out because you left the gate open. You don’t infer that the car won’t start because you left the radio on.
While you would be good at spatial relations, you would not grasp the causes and effects described by physics. You will not infer any unobserved causal forces, whether they be gravitational or spiritual. For example, you would not infer that a ball moved because a force was transferred to it when it was hit by another, yet because of your inability to draw inferences, you would do better in Vegas at the gaming tables. You would bet with the house and not try to infer any causal relationship between winning and losing other than chance. No lucky tie or socks or tilt of the head. You would not string out some cockamamy story about why you did something or felt some way, not because you aren’t capable of language, but again because you don’t infer cause and effect. You won’t be a hypocrite and rationalize your actions. You would also not infer the gist of anything, but would take everything literally. You would have no understanding of metaphors or abstract ideas. Without inference you would be free of prejudice, yet not inferring cause and effect would make learning more difficult. What processing comes bubbling up in your separate hemispheres determines what the contents of that hemisphere’s conscious experience will be.
Feelings
We have all experienced the longing to return to a favorite spot in the world, a place we once relished and remember so fondly that we had to go back and recapture the moment. And yet when we go back to visit the second time, it is not quite the same. The feelings are different. It is not that they are bad or good. It is that they are different.
My wife and I recently returned to Ravello, a place we had found magical in the past. It still had its natural beauty. It still had its history, culture, and, best of all, its people. Yet it felt different to us. It didn’t seem to match our feelings about the place, rooted in our previous experience. Were we misremembering something or were we “feeling” different about life in general, and were those different feelings coloring our current experience?
Our commonsense idea about past experiences is that each has a feeling to it that is specified for the particular event in question. The actual feeling itself is tied to the actual experience, and we expect we can recapture the feeling by replicating the experience. You felt happy and excited when you vacationed in place x; if you return, then you will again feel happy and excited. This may be why people buy time-share condos. Their first visit is great, but the next … and the next? Repeat the event and we expect the original feeling will come along automatically. I am suggesting that it doesn’t. This is not how to think about it.
That magical moment that we relished in the past is now stored as information about that past event. It is placed in memory in ways we still don’t understand, but it is symbolic information, cold and formal, just as DNA is symbolic information—and, just like DNA, it has a physical structure. Contained within that informational structure may be the fact that the event was associated with positive feelings, but the feelings themselves are not stored, just information about them. As a memory bubble pops up, so do bubbles spewing forth our current feeling about it. Feelings are from another system with its own processing bubbles, separate from the memory system. In short, I am suggesting that uncoupling the emotional dimension reveals that different systems are converging in time to produce a feeling about a memory. For an analogy, it’s like the musical soundtrack of a dramatic movie scene. They are separate, but when they are put together, the soundtrack adds emotion. As one bubble quickly passes to the next, we have the illusion of feeling about the remembered event.
So we have memory bubbles and feeling bubbles. When we think about that past moment, our feelings about it are not actually the feelings of the past moment; rather, they are our current feelings, which we map onto the past moment. Usually they, too, are positive, but the feelings themselves are not bolted to the actual past memories. This is more obvious when today’s feeling is the opposite of the original feeling. For example, say you are recalling the moment when you received the results of an exam you failed in college. Your memory tells you that you felt bad at the time, right? But say that, because of this failure, you marched yourself into the professor’s office and asked for help, which led to you actually becoming engrossed in the subject, which led to a career in the field. When you look back at the event of the bad grade, the current you knows where it led and now can think of it in only positive terms. Intellectually you remember that you felt bad, but you just can’t reincarnate those feelings. Perhaps more resistant to changes in perspective are feelings of embarrassment. You may still blush thinking of some past social transgression. Yet sometimes you can only laugh and shake your head at what embarrassed the younger (teenage) you: hiding on the floor of the backseat at the drive-in so no one would see you with your parents. Did I really do that? No blushing involved now, or maybe blushing for an entirely different reason.
The modules that produce raw feelings are different from the ones that produce thoughts, memory, decisions, and so forth. What we are feeling at a moment in time during an event becomes an aspect of the memory of the event, a dimension, a piece of information we can label and neurally code and include in our memory.
The actual feeling, however, comes from another, totally independent contractor in the brain. On a revisit, it can be on different neurological settings from the previous visit. At both times, it was those neurological settings that were driving your feeling about the visit. The first visit involves the challenge of the unknown, curiosity, adventure, often youth, and sometimes adrenaline. On a revisit, you are returning older, with more life experience under your belt, to familiar territory; it is not so challenging, your curiosity is not so piqued, you know more or less what to expect, you have less adrenaline pumping. You feel different, not necessarily worse or better, just different. This is true not just for returning to locales but also for trying to recapture any past experience. Neil Young describes this well: “I still try to be that way, but, you know, I am not twenty-one or twenty-two.… I am not sure that I could re-create that feeling, it has to do with how old I was, what was happening in the world, what I had just done, what I wanted to do next, who I was living with, who my friends were, what the weather was.”9
Sentio Ergo Sum
A few years back, Steven Pinker observed: “Something about the topic of consciousness makes people, like the White Queen in Through the Looking Glass, believe six impossible things before breakfast. Could most animals really be unconscious—sleepwalkers, zombies, automata, out cold? Hath not a dog senses, affections, passions? If you prick them, do they not feel pain?”10 Jaak Panksepp agreed with Pinker that to deny that is to believe the impossible, and blamed Descartes, thinking he was way out of line in denying animals consciousness. Not only that, he thought Descartes would have saved us all a lot of trouble if, when he asked “What is this ‘I’ that ‘I’ know?” he had just replied, “I feel, therefore I am,” and left cognition out of the subjective-experience equation. Panksepp would have agreed with Pattee that most everyone since Descartes has been looking way too high in the evolutionary tree for how neural systems manage to produce subjective affective experience.11
Panksepp proposed that subjective affective experience arose when the evolutionarily old system of emotions linked up with a primitive type of neural “body map” that delimits the “self” from the external world.12 To form the body map would only require sensations from inside and outside the body to be tacked onto sheets of related neurons in the brain. He argued then that the two things necessary for subjective experience are information about the internal and external states of the agent (recorded symbolically), and the construction of an integrated neural simulation of the agent in space: a quick and dirty model, built from the firings of neurons. Information and construction, the same complementarity we saw in DNA. Higher cognition or knowing that you have a “self” (a.k.a. “self-awareness”) is not part of the original recipe. To move through the environment safely and efficiently, to eat when you are hungry, and so forth, you do not need to know that you are self-aware, but you do need to know the boundaries of your body in relation to the space that surrounds it. If you didn’t know that, you would be forever bumping into things and misjudging everything from fitting into a cozy den to jumping from one rock to another. And you also need to have the motivation to act in ways that promote survival and reproduction. That is, you don’t need bubbles roiling up from a highly evolved cortex to be aware of a subjective experience. Descartes only needed signals from the subcortex to feel he was an “I”; he didn’t need to think about it.
In fact, even an insect needs to have information about its body in space in order to move safely and effectively. I have been outmaneuvered by many a fly, wielding my swatter to no effect. The biologist Andrew Barron and philosopher of neuroscience Colin Klein, both from Australia’s Macquarie University, began prowling around the world of insect brains and found that structures known as the central complex performed functions analogous to those of parts of the vertebrate midbrain, generating “a unified spatial model of the state and position of the insect in the environment.”13 That is, functions that locate them in space are present in the brains of cockroaches and crickets, locusts and butterflies, fruit flies and honeybees, just as they are in the midbrain of vertebrates. In short, the task of ordering the plethora of systems needed to perform an action is an extensive biological feature of complex organisms. Bugs have it, we have it. Barron and Klein, agreeing with Panksepp and Merker, conclude, “This integrated and egocentric representation of the world from the animal’s perspective is sufficient for subjective experience.” They also think this awareness of the body in space is sufficient for the insects they have studied, suggesting that they, too, have a form of subjective experience, which was present in a common ancestor of both vertebrates and invertebrates back in the Cambrian explosion, about 550 million years ago (MYA).
They are not alone. The neurobiologists Nicholas Strausfeld, from the University of Arizona, and Frank Hirth, from King’s College London, are also venturing out on their own limb of evolution’s tree. They did a massive review of the anatomical, developmental, behavioral, and genetic characteristics of vertebrate basal ganglia and compared them with those of the central complex of arthropods (of which insects are but a branch). They found so many similarities that they were prompted to conclude that the arthropod central complex and vertebrate basal ganglia circuitries shared a common ancestry.14 In fact, the two are derived from an evolutionarily conserved genetic program. That is, the circuits essential to behavioral choice originated very early in evolution. The ancestor that we vertebrates share with the arthropods was already scampering around with such a circuit, with bubbles of processed information about its location and sensations popping up to guide its actions. Strausfeld and Hirth even suggest that common ancestor’s brain gear was sufficient to support phenomenal experience. While their view may be overdrawn, their work does alert us to how deeply conserved the basic mechanisms we unearth in humans may be. This is the beauty of evolutionary and comparative research. Aspects of our own mental life that we assume to be unique constructions of the human brain have, in fact, been around for a very long time and are mainly elaborated upon by human brains.
Methodic or Chaotic Bubbles?
Our conscious experience is a continuous, smoothly running flow of thoughts and sensations. How can this come about with all these bubbles battling it out for precedence? Do the bubbles burst willy-nilly, or are they the product of a dynamic control system? Is there a control layer giving some bubbles the nod and quashing others?
One way a module’s processing is controlled is by the input it receives. Let’s say you bite into a chocolate truffle made with unsweetened chocolate. No afferent nerve, that is, one that comes from the periphery to the brain, is activated by taste cells that detect sweetness, no module that processes such sensations is activated, so you do not taste anything sweet, and no sweet information is getting processed. Instead, the taste cells that detect bitterness are activated, and your mouth is flooded with a bitter taste. Bitter information is getting processed. Swap out that unsweetened chocolate for an identical-looking milk chocolate one, and that sweet module is up and running, too, bubbling sweetness into your awareness like a house on fire, outcompeting bitterness by a landslide. It is as if bitterness is now a distant memory and the moment is owned by sweetness, until the next bubble arrives. No cognition is required here. Somehow, that sweet signal won the bubblefest. Did it get some additional help?
Some form of selective signal enhancement has been found in animals ranging from crabs15 to birds16 to primates,17 suggesting it is an ability shared with our last common ancestor, which was roaming around about 550 MYA. The earliest manifestation of this “data control” ability was a rudimentary form of attention, a process that helped manage the onslaught of sensory information besieging an exploring hunk of cells. A signal-enhancing process appeared early in evolution to help organisms sort out which of all the stimuli bombarding them might be more relevant for survival (better to give priority to information about an approaching threat, meal, or mate than to much else) and has been conserved across all life forms, stemming from this early organism.
Steven Wiederman and David O’Carroll at the University of Adelaide in Australia discovered that in the modern-day dragonfly brain there is a single visual neuron that selects one particular prey-like visual target and follows it, completely ignoring another.18 This is interesting not only because it demonstrates that dragonflies have a form of competitive selection, which is required for visual attention, but also because a selective attention process is accomplished by a single cell. In vertebrates, selective signal enhancement evolved into what we now call attention, a sophisticated mechanism that controls incoming data and, through that, our minds. Thus, we may be engrossed watching an exciting movie, but one squeal of a fire alarm and our “data control” system immediately enhances that screeching input, jerking our minds away from the movie and into action.
Yet, although selective signal enhancement has some control over our minds, our minds also control our attention to some extent. What I mean is that attention has two components, bottom-up and top-down. If you are meeting a blind date with a red flower in her hair, your eyes will be swiveling around looking at hairdos and not much else. Your attention is top-down, being guided by your plan to find the unknown date. Bottom-up attention will only get you so far in the survival game. Those organisms that developed top-down attention had an edge, and it became de rigueur. This top-down attention ability is highly developed in both birds and mammals, whose common ancestor was cruising around 350 million years ago, so this ability is at least that old, but evolutionarily newer than bottom-up attention. An add-on app: a new layer.
Once again Pattee makes a useful suggestion about how such a layer could evolve. The failure of one layer is the basic force or condition for a new one to arise:
When a system fails to have a representation or a description to handle a particular situation, it leaves a power vacuum so to speak, or a decision vacuum. I would call it a kind of instability, when a decision needs to be made and there is no decision procedure. One then has ambiguity, and small causes can have large effects. This is, in effect, a crisis in the system, and there can arise then a new type of behavior.19
So as systems became more complex, some sort of control layer was needed to manage the plethora of independent stimuli and resultant behavior. While stimulus enhancement is great, a control layer was needed to somehow orchestrate the squawking of all the modules.
A Famous Control Layer Malfunction
As I discussed earlier, people with right parietal lobe lesions can experience neglect of the left side of the visual field even in their imaginations and memories. This famous observation was originally made by the brilliant Italian neuropsychologist Edoardo Bisiach.20 In a nutshell, he asked patients to describe from memory the Piazza del Duomo in Milan from two different perspectives. It is a beautiful site, with buildings of a particular kind lining each side of the piazza and the grand cathedral at the end. Everybody in Milan can imagine it with ease.
When asked to describe the Duomo as if they were standing in front of it and looking straight at it, the patients easily did so, but they only described the buildings lining the right (north) side of the square. They left out any description of the buildings on the left (south) side. Then Bisiach followed up by asking them to imagine themselves turned around 180 degrees and to describe the square from the perspective of standing on the front steps of the Duomo. Now the very same patients easily described the buildings on the right (south) side looking out from the Duomo and never mentioned the very buildings on the left (north) side that they had just described when imagining facing in the opposite direction!
This dramatic clinical example reveals the existence of two completely different sets of modules. Clearly, the modules generating a mental image remain intact, and all the information is present, but those modules are controlled by an additional module that evaluates from which side of space the image will be reported, and this module is malfunctioning. Years later, the neurologist Denise Barbut and I were able to examine a case at New York Hospital with similar damage to the right parietal lobe and replicate Bisiach’s findings.21
Consciousness Enriched by Evolution
When it comes to consciousness, we seem to have forgotten the fact that our brains evolved by adding complexity. Over the course of evolution, modules and layers have been annexed over time to solve one perturbation after another, changing and increasing the content of our conscious experiences along the way. Each layer has its own independent rules for processing and passes its handiwork, its processing bubble, on to the next. While the processing within a module, going from layer to layer, may be serial, multiple modules are running in parallel, bubbles roiling up from each, coming to a final realization.
In the bubble analogy, the results of processing from various modules burst into our conscious awareness from one snippet of time to the next. Most likely, one bubble is boosted into the limelight by a control layer with a protocol made up of arbitrary rules, rules that have been selected because they have provided the content of consciousness with the most reliable, apt information for the situation being faced. A better and more reliable rule comes along, and the protocol can be changed. For example, consider a belief bubble that comes popping up to consciousness. Say you believe that saturated fat is unhealthy and eating it is making you gain weight. You believe that you should replace those calories with carbohydrates. You believe this because it is what you have been told by public health officials, nutritionists, and your doctor. When you are grocery shopping, bubbles are popping up, guiding you to stay clear of saturated fat. But then you make an observation. Your experience does not support the official’s claims. The more fat you cut out of your diet and replace with carbohydrates, the more weight you gain. Then you read a tome in which the author reviews and evaluates all the research behind this claim, and finds that not only does most of the research not meet the standards of good science, but the small fraction that does fails to support the claim. In fact, it suggests the opposite is true.22 You end up convinced. You buy butter and cream and eat it. You lose weight. At the grocery store the cream bubbles take over. A better and more reliable rule has come along and the protocol has changed. It makes for a better cup of coffee, too.
Importantly, gaps, modules, and layers can help us understand the behavior we observe in individuals who suffer brain lesions. If we lose some neural tissue that processes particular aspects of information, then that information is no longer part of our repertoire of bubbles and no longer provides content to our conscious experience. The same is true when the right hemisphere is separated from the left: neither hemisphere has bubbles from its opposite member popping up to enrich its conscious experience, leaving the conscious experience of each hemisphere impoverished.