Review of “Incognito: The Secret Lives of the Brain” by David Eagleman

Most of our brain activity is not conscious –  from processes that maintain our basic physiology to those that determine how we catch a baseball and play a piano well. Further, these unconscious processes include those that influence our basic perceptions of the world. Our opinions and deepest held beliefs – those that we prefer to feel that our conscious mind completely determines –  are shaped largely by unconscious processes. The book, “Incognito: Secret Lives of the Brain” by David Eagleman, is an engaging account of those processes – packed with practical and interesting examples and insight. Eagleman is not only a neuroscientist, but an extremely clear and engaging writer. His writing, completely accessible to the non expert, is filled with solid neuroscience, packaged in a way that not only provides interesting information, but also builds perspective. It’s the first book that I’ve encountered that delves deeply into this particular subject. We mostly think of our brains as generating conscious thought, but, as he explains it’s just the small tip of the iceberg.  

I recently blogged about a meeting at Stanford on wearable technology. One of the best talks at this conference was by David Eagleman – all about the “umwelt” or how we experience the world through our relatively limited senses, as well as how we may expand and enhance our umwelt with devices that convert previously unperceived information to sensory experience. The moment his talk was finished, I bought two of his books – it was that good. This book was one of them.

He summarizes his book early on as follows: “Your consciousness is like a tiny stowaway on a transatlantic steamship, taking credit for the journey without acknowledging the massive engineering underfoot. This book is about that amazing fact: how we know it, what it means, and what it explains about people, markets, secrets, strippers, retirement accounts, criminals, artists, Ulysses, drunkards, stroke victims, gamblers, athletes, bloodhounds, racists, lovers, and every decision you’ve ever taken to be yours.” (p.4)

He starts with an example of why we may find another person attractive. We may verbalize characteristics but these fall short. The deep mechanisms for attraction are hardwired into us – below our conscious processes. We have surprisingly little access or control of these mechanisms. Other examples include how experts perform well-practiced movements. Again, these actions may have started as conscious processes, but over time, they have become automatic. Playing a piano well depends on repeated practice moving the neural processes involved with the actions from slow and awkward conscious space to unconscious execution. He also claims that unconscious processes are behind our of our best ideas and insights.   

Eagleman delves into our perceptual world and all that we don’t experience – describing how our senses are exquisitely tuned to information critical to our survival and how what we experience is a fine sliver of possible sensations. He then takes this further to draw the comparison to the tiny sliver of mental processes that we have access to: “By analogy to your perception of the world, your mental life is built to range over a certain territory, and it is restricted from the rest. There are thoughts you cannot think. You cannot comprehend the sextillion stars of our universe, nor picture a five-dimensional cube, nor feel attracted to a frog. If these examples seem obvious (Of course I can’t!), just consider them in analogy to seeing in infrared, or picking up on radio waves, or detecting butyric acid as a tick does. Your “thought umwelt” is a tiny fraction of the “thought umgebung.” (p.82)

So just as our senses are limited, so is our consciousness – it has many blind spots.

Drawing upon an eye-opening experiment that he has the reader perform, he gives an example of our social hardwiring that we are not consciously aware of. To illustrate how our brains are best at social interactions but less so in logic, he first shares a logic puzzle that when posed without a social context, most get wrong, but when posed in a social framework (i.e. detecting cheaters) is solved easily. It’s the same problem presented in two contexts – one which is alien to our brain (pure logic) and one which we evolved to master (social situations): “The brain cares about social interaction so much that it has evolved special programs devoted to it: primitive functions to deal with issues of entitlement and obligation. In other words, your psychology has evolved to solve social problems such as detecting cheaters— but not to be smart and logical in general.” (p.86).

Within his discussion of unconscious processes he includes some classic insights into known brain functions that are better described than anywhere I’ve seen in the literature. In one example he eloquently describes how the amygdala is invoked to store emotionally charged memories. “For instance, under normal circumstances, your memories of daily events are consolidated (that is, “cemented in”) by an area of the brain called the hippocampus. But during frightening situations— such as a car accident or a robbery— another area, the amygdala, also lays down memories along an independent, secondary memory track. Amygdala memories have a different quality to them: they are difficult to erase and they can pop back up in “flashbulb” fashion— as commonly described by rape victims and war veterans. In other words, there is more than one way to lay down memory.” (p.126)

Also included is perhaps the clearest description of one of the more famous cognitive neuroscience experiments of all time – and still the best example of the “inference engine” that I know. It’s worth quoting in full here (bold print is my own): “Not only do we run alien subroutines; we also justify them. We have ways of retrospectively telling stories about our actions as though the actions were always our idea. As an example at the beginning of the book, I mentioned that thoughts come to us and we take credit for them (“I just had a great idea!”), even though our brains have been chewing on a given problem for a long time and eventually served up the final product. We are constantly fabricating and telling stories about the alien processes running under the hood. To bring this sort of fabrication to light, we need only look at another experiment with split-brain patients. As we saw earlier, the right and left halves are similar to each other but not identical. In humans, the left hemisphere (which contains most of the capacity to speak language) can speak about what it is feeling, whereas the mute right hemisphere can communicate its thoughts only by commanding the left hand to point, reach, or write. And this fact opens the door to an experiment regarding the retrospective fabrication of stories. In 1978, researchers Michael Gazzaniga and Joseph LeDoux flashed a picture of a chicken claw to the left hemisphere of a split-brain patient and a picture of a snowy winter scene to his right hemisphere. The patient was then asked to point at cards that represented what he had just seen. His right hand pointed to a card with a chicken, and his left hand pointed to a card with a snow shovel. The experimenters asked him why he was pointing to the shovel. Recall that his left hemisphere (the one with the capacity for language), had information only about a chicken, and nothing else. But the left hemisphere, without missing a beat, fabricated a story: “Oh, that’s simple. The chicken claw goes with the chicken, and you need a shovel to clean out the chicken shed. When one part of the brain makes a choice, other parts can quickly invent a story to explain why.” (pp.133-134)

I personally find this story so important to explain so much of human behavior. We grow up and live in an environment which is constantly shaping our beliefs – mostly at a level beneath our awareness, and then “without missing a beat” we justify our beliefs so quickly with a seemingly rational explanation. To me this is the foundation of some of the most deep divisions in our world and perhaps the source of so many conflicts. We can see it happening today. Perfectly intelligent people have wildly divergent beliefs that cannot be moved no matter how rational the arguments are on either side. We tend to talk right by each other because no one is fully aware of the true sources of our deeply held beliefs, therefore cannot find the verbal/rational leverage to change them.

As Gazzaniga put it, ‘These findings all suggest that the interpretive mechanism of the left hemisphere is always hard at work, seeking the meaning of events. It is constantly looking for order and reason, even when there is none— which leads it continually to make mistakes.’”(p.134)

Later, he puts forth his own hypothesis for the role of consciousness itself: “From an evolutionary point of view, the purpose of consciousness seems to be this: an animal composed of a giant collection of zombie systems would be energy efficient but cognitively inflexible. It would have economical programs for doing particular, simple tasks, but it wouldn’t have rapid ways of switching between programs or setting goals to become expert in novel and unexpected tasks. In the animal kingdom, most animals do certain things very well (say, prying seeds from the inside of a pine cone), while only a few species (such as humans) have the flexibility to dynamically develop new software.” (p.142)

So consciousness allows flexibility – or put another way, substantially increases the possible actions that the organism can take. Engleman argues that it’s likely possessed across all animals – with the degree of intellectual flexibility reflecting the degree of consciousness.

Later in the book, Engleman delves into the difficult and charged question of free will: “So in our current understanding of science, we can’t find the physical gap in which to slip free will— the uncaused causer— because there seems to be no part of the machinery that does not follow in a causal relationship from the other parts.” (p. 166)

If our actions, decisions, and beliefs are a result of causal interactions of subsystems in our brains, is free will an illusion? Can neuroscience test for free will? He brings up a fascinating example of an early test and surprising results: “In the 1960s, a scientist named Benjamin Libet placed electrodes on the heads of subjects and asked them to do a very simple task: lift their finger at a time of their own choosing. They watched a high-resolution timer and were asked to note the exact moment at which they “felt the urge” to make the move. Libet discovered that people became aware of an urge to move about a quarter of a second before they actually made the move. But that wasn’t the surprising part. He examined their EEG recordings— the brain waves— and found something more surprising: the activity in their brains began to rise before they felt the urge to move. And not just by a little bit. By over a second. In other words, parts of the brain were making decisions well before the person consciously experienced the urge.” (p. 167)

So where did the will come from? He takes this concept further to suggest that criminal action is mostly the result of processes outside of conscious control. However, he still argues that of course such criminals should be taken off the streets, but perhaps understanding this process may foster better ways of changing their brains such that their behavior eventually becomes more socially acceptable. He does venture that the prefrontal cortex has “veto power” which perhaps can be trained.

Engleman then appears to pull back just a bit: “Given the steering power of our genetics, childhood experiences, environmental toxins, hormones, neurotransmitters, and neural circuitry, enough of our decisions are beyond our explicit control that we are arguably not the ones in charge. In other words, free will may exist— but if it does, it has very little room in which to operate. So I’m going to propose what I call the principle of sufficient automatism. The principle arises naturally from the understanding that free will, if it exists, is only a small factor riding on top of enormous automated machinery. So small that we may be able to think about bad decision making in the same way we think about any other physical process, such as diabetes or lung disease. The principle states that the answer to the free-will question simply does not matter.” (p. 170)

He gives a compelling argument that criminal action can be placed in a spectrum similar to other brain disorders that have been characterized and treated with varying success: “What accounts for the shift from blame to biology? Perhaps the largest driving force is the effectiveness of the pharmaceutical treatments. No amount of beating will chase away depression, but a little pill called fluoxetine often does the trick. Schizophrenic symptoms cannot be overcome by exorcism, but can be controlled by risperidone. Mania responds not to talking or to ostracism, but to lithium. These successes, most of them introduced in the past sixty years, have underscored the idea that it does not make sense to call some disorders brain problems while consigning others to the ineffable realm of the psychic. Instead, mental problems have begun to be approached in the same way we might approach a broken leg.” (p. 172)

Eric Wong adds his perspective about consciousness and free will here: “In computer program speak, I think of both consciousness and free will as properties of an ‘event handler’ like piece of software that just happens to work at the top level, able to execute other software, and the process to which control is returned after any other subroutine completes. The concept of free will is just a perceptual artifact of the fact that our brains are programmed to hang out at critical points, so that apparently meaningful ‘decisions’ are frequent occurrences.” 

Later in the book, he takes on the limits of modern neuroimaging methods for understanding our unconscious processes, stating that the imaging resolution is much too coarse and sensitivity too small to understand the multitudes of processes that may play a role. He then hits the nail on the head regarding a current focus and major challenge of neuroimaging today: “For example, a study by psychologists Angela Scarpa and Adrian Raine found that there are measurable differences in the brain activity of convicted murderers and control subjects, but these differences are subtle and reveal themselves only in group measurement. Therefore, they have essentially no diagnostic power for an individual.” (p. 174)

So true for all neuroimaging – we need to accelerate the movement away from group averages to individuals. I believe that there is reason to have high hopes as promising results have recently been demonstrated in EEG, MEG, and fMRI.

Back to blameworthiness for those who carry out actions or have beliefs so far outside of the social norms that they need to be removed from society. Here he shifts the focus and states that blameworthiness is simply the wrong question. Most criminals don’t have measurable biologic problems, therefore are thought to be freely acting. On the other hand many with brain disorders do not carry out criminal acts. The sources of human behavior are incredibly complex. He flips the argument, stating that the actions themselves suggest that there are indeed biologic issues and that we simply don’t have the technology to detect them yet. We should instead focus on the best methods for rehabilitation. He mentions work by Stephen LaConte in real time feedback for giving the frontal lobes practice in suppressing impulsive short-term circuits. Beyond this, he does not have many solid suggestions for this as it is indeed a hard problem.

So is that all there is? Is our very essence the result of a vastly complex array of subconscious processes with us having the illusion of free will? His view, as expected, is hopeful for more nuance: “The situation is likely to be the opposite: as we plumb further down, we will discover ideas much broader than the ones we currently have on our radar screens, in the same way that we have begun to discover the gorgeousness of the microscopic world and the incomprehensible scale of the cosmos.”  The sense of agency is so strong it’s hard to fathom that it’s an illusion. On other other hand, as we dig deeper into our unconsious influences, the picture might become more clear. Perhaps, in some future time, armed with this deeper awareness of the hidden influences of our thoughts – and perhaps some sophisticated biofeedback tools, we may be able to pull ourselves further out of our subjective experience where we can more optimally train our brains or change our beliefs…

From here, he takes on the problem of a “soul.” “All of this leads to a key question: do we possess a soul that is separate from our physical biology— or are we simply an enormously complex biological network that mechanically produces our hopes, aspirations, dreams, desires, humor, and passions? The majority of people on the planet vote for the extra biological soul, while the majority of neuroscientists vote for the latter: an essence that is a natural property that emerges from a vast physical system, and nothing more besides.” (p.203)

Like most scientists, he agrees with the materialist view: “The materialist viewpoint states that we are, fundamentally, made only of physical materials. In this view, the brain is a system whose operation is governed by the laws of chemistry and physics— with the end result that all of your thoughts, emotions, and decisions are produced by natural reactions following local laws to lowest potential energy. We are our brain and its chemicals, and any dialing of the knobs of your neural system changes who you are.”

…however he draws the line when the materialist view moves to a reductionist view. In fact, here he hits at perhaps the central problem in neuroscience in trying to understand the brain. “Just because a system is made of pieces and parts, and just because those pieces and parts are critical to the working of the system, that does not mean that the pieces and parts are the correct level of description.”  (p. 216).

He then clarifies a bit: “The future of understanding the mind lies in deciphering the patterns of activity that live on top of the wetware, patterns that are directed both by internal machinations and by interactions from the surrounding world. Laboratories all over the world are working to figure out how to understand the relationship between physical matter and subjective experience, but it’s far from a solved problem.” (p. 204).

This is an easily misunderstood point. All the details are important, however, the principles of human thought and behavior cannot be explained by one level of description. Understanding the action potential or even networked activity in the brain is but one spatial and temporal scale. “A meaningful theory of human biology cannot be reduced to chemistry and physics, but instead must be understood in its own vocabulary of evolution, competition, reward, desire, reputation, avarice, friendship, trust, hunger, and so on…” (p. 218) These wider contexts of understanding may be critical for truly understanding conscious brain processes.

And finally, a final quote that lines up with much of what my co-blogger, Eric Wong, has been saying in his posts. There are many many layers of understanding that span spatial and temporal scales and perhaps defy explanation given our current understanding, that need to be uncovered to truly understand the brain in full. “Each day neuroscientists go into the laboratory and work under the assumption that understanding enough of the pieces and parts will give an understanding of the whole. This break-it-down-to-the-smallest-bits approach is the same successful method that science has employed in physics, chemistry, and the reverse-engineering of electronic devices. But we don’t have any real guarantee that this approach will work in neuroscience. The brain, with its private, subjective experience, is unlike any of the problems we have tackled so far. Any neuroscientist who tells you we have the problem cornered with a reductionist approach doesn’t understand the complexity of the problem. Keep in mind that every single generation before us has worked under the assumption that they possessed all the major tools for understanding the universe, and they were all wrong, without exception. Just imagine trying to construct a theory of rainbows before understanding optics, or trying to understand lightning before knowledge of electricity, or addressing Parkinson’s disease before the discovery of neurotransmitters.” (p. 223)

So, Eagleman’s view is that understanding the brain is not impossible, but realistically, we have not started to even figure out how to approach some of the unknowns. The human brain is much more than its conscious processes and likely an embodiment of principles more subtle and profound than those that we infer by basic reductionistic approaches.

Eagleman, with this book, has succeeded in drawing us in, opening our eyes, then making us uncomfortable with questions of free will, souls, and reductionistic views of the brain. He dissects these concepts with skill, presenting a convincing argument that while collecting more data is useful, learning to dismiss outdated concepts and form new better questions is what drives our understanding.  

A satisfying read on a relatively unexplored subject: The book is clear, entertaining, and thought-provoking. 

Author: Peter Bandettini

Peter Bandettini has been working in functional brain imaging since he started his Ph.D. thesis work on fMRI method development in 1991 in the Biophysics Department at the Medical College of Wisconsin (MCW). After completing a post doc at Massachusetts General Hospital in 1996 and a brief Assistant Professorship at MCW, he became Chief of Functional Imaging Methods and Director of the Functional MRI Facility at the National Institutes of Health in Bethesda, MD. He was Editor-In-Chief of NeuroImage from 2011-2017 and has been active in both the MRI community (International Society for Magnetic Resonance in Medicine) and the Brain Imaging Methods community (Organization for Human Brain Mapping). All his views and posts are his own.

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