The human brain isn’t really empty, of course. But it does not contain most of the things people think it does – not even simple things such as ‘memories’. ... Forgive me for this introduction to computing, but I need to be clear: computers really do operate on symbolic representations of the world. They really store and retrieve. They really process. They really have physical memories. They really are guided in everything they do, without exception, by algorithms. ... Humans, on the other hand, do not – never did, never will. Given this reality, why do so many scientists talk about our mental life as if we were computers? ... A wealth of brain studies tells us, in fact, that multiple and sometimes large areas of the brain are often involved in even the most mundane memory tasks. When strong emotions are involved, millions of neurons can become more active.

Our world had spun around the sun more than 30 times since, though Henry’s world had stayed still, frozen in orbit. This is because 1953 was the year he received an experimental operation, one that destroyed most of several deep-­seated structures in his brain, including his hippocampus, his amygdala and his entorhinal cortex. The operation, performed on both sides of his brain and intended to treat Henry’s epilepsy, rendered him profoundly amnesiac, unable to hold on to the present moment for more than 30 seconds or so. That outcome, devastating to Henry, was a boon to science: By 1986, Patient H.M. — as he was called in countless journal articles and textbooks — had become arguably the most important human research subject of all time, revolutionizing our understanding of how memory works. ... Of course, Henry didn’t know that. No matter how many times the scientists told him he was famous, he’d always forget. ... one of the things about Henry that fascinated scientists: His amnesia often appeared, as they termed it, pure. There was an abyss in his brain that all the passing events of his life tumbled into, but on the surface he could seem almost normal. ... Even as a nonscientist, I couldn’t help noticing that some of the unpublished data I came across while reporting my book went against the grain of the established narrative of Patient H.M. For example, unpublished parts of a three-page psychological assessment of Henry provided evidence that even before the operation that transformed Henry Molaison into the amnesiac Patient H.M., his memory was already severely impaired. The causes and significance of Henry’s preoperative memory deficits can be debated, but their existence only underscores the importance of preserving the complete record of the most important research subject in the history of memory science.

Learning math and then science as an adult gave me passage into the empowering world of engineering. But these hard-won, adult-age changes in my brain have also given me an insider’s perspective on the neuroplasticity that underlies adult learning. ... In the current educational climate, memorization and repetition in the STEM disciplines (as opposed to in the study of language or music), are often seen as demeaning and a waste of time for students and teachers alike. Many teachers have long been taught that conceptual understanding in STEM trumps everything else. And indeed, it’s easier for teachers to induce students to discuss a mathematical subject (which, if done properly, can do much to help promote understanding) than it is for that teacher to tediously grade math homework. What this all means is that, despite the fact that procedural skills and fluency, along with application, are supposed to be given equal emphasis with conceptual understanding, all too often it doesn’t happen. Imparting a conceptual understanding reigns supreme—especially during precious class time. ... The problem with focusing relentlessly on understanding is that math and science students can often grasp essentials of an important idea, but this understanding can quickly slip away without consolidation through practice and repetition. Worse, students often believe they understand something when, in fact, they don’t. ... Chunking was originally conceptualized in the groundbreaking work of Herbert Simon in his analysis of chess—chunks were envisioned as the varying neural counterparts of different chess patterns. Gradually, neuroscientists came to realize that experts such as chess grand masters are experts because they have stored thousands of chunks of knowledge about their area of expertise in their long-term memory. ... As studies of chess masters, emergency room physicians, and fighter pilots have shown, in times of critical stress, conscious analysis of a situation is replaced by quick, subconscious processing as these experts rapidly draw on their deeply ingrained repertoire of neural subroutines—chunks. ... Understanding doesn’t build fluency; instead, fluency builds understanding.

The difference between the 4004 and the Skylake is the difference between computer behemoths that occupy whole basements and stylish little slabs 100,000 times more powerful that slip into a pocket. It is the difference between telephone systems operated circuit by circuit with bulky electromechanical switches and an internet that ceaselessly shuttles data packets around the world in their countless trillions. It is a difference that has changed everything from metal-bashing to foreign policy, from the booking of holidays to the designing of H-bombs. ... Moore’s law is not a law in the sense of, say, Newton’s laws of motion. But Intel, which has for decades been the leading maker of microprocessors, and the rest of the industry turned it into a self-fulfilling prophecy. ... That fulfilment was made possible largely because transistors have the unusual quality of getting better as they get smaller; a small transistor can be turned on and off with less power and at greater speeds than a larger one. ... “There’s a law about Moore’s law,” jokes Peter Lee, a vice-president at Microsoft Research: “The number of people predicting the death of Moore’s law doubles every two years.” ... making transistors smaller has no longer been making them more energy-efficient; as a result, the operating speed of high-end chips has been on a plateau since the mid-2000s ... while the benefits of making things smaller have been decreasing, the costs have been rising. This is in large part because the components are approaching a fundamental limit of smallness: the atom. ... One idea is to harness quantum mechanics to perform certain calculations much faster than any classical computer could ever hope to do. Another is to emulate biological brains, which perform impressive feats using very little energy. Yet another is to diffuse computer power rather than concentrating it, spreading the ability to calculate and communicate across an ever greater range of everyday objects in the nascent internet of things. ... in 2012 the record for maintaining a quantum superposition without the use of silicon stood at two seconds; by last year it had risen to six hours. ... For a quantum algorithm to work, the machine must be manipulated in such a way that the probability of obtaining the right answer is continually reinforced while the chances of getting a wrong answer are suppressed.

But after stopping on a desolate gravel road next to a sign for a gas station, Santillan got the feeling that the voice might be steering him wrong. He’d already been driving for nearly an hour, yet the ETA on the GPS put his arrival time at around 5:20 P.M., eight hours later. He reentered his destination and got the same result. Though he sensed that something was off, he made a conscious choice to trust the machine. He had come here for an adventure, after all, and maybe it knew where he was really supposed to go. ... It’s comforting to know where you are, to see yourself distilled into a steady blue icon gliding smoothly along a screen. With a finger tap or a short request to Siri or Google Now—which, like other smartphone tools, rely heavily on data from cell towers and Wi-Fi hot spots as well as satellites—a wonderful little trail appears on your device, beckoning you to follow. ... The convenience comes at a price, however. There’s the creepy Orwellian fact of Them always knowing where We are (or We always knowing where They are). More concerning are the navigation-fail horror stories that have become legend. ... Enough people have been led astray by their GPS in Death Valley that the area’s former wilderness coordinator called the phenomenon “death by GPS.” ... By turning on a GPS every time we head somewhere new, we’re also cutting something fundamental out of the experience of traveling: the adventures and surprises that come with finding—and losing—our way. ... Individuals who frequently navigate complex environments the old-fashioned way, by identifying landmarks, literally grow their brains.

Whether it takes the form of a touch of the Holy Spirit at a Florida revival meeting or a dip in the water of the Ganges, the healing power of belief is all around us. Studies suggest that regular religious services may improve the immune system, decrease blood pressure, add years to our lives. ... Religious faith is hardly the only kind of belief that has the ability to make us feel inexplicably better. ... just as a good performance in a theater can draw us in until we feel we’re watching something real, the theater of healing is designed to draw us in by creating powerful expectations in our brains. These expectations drive the so-called placebo effect, which can affect what happens in our bodies as well. Scientists have known about the placebo effect for decades and have used it as a control in drug trials. Now they are seeing placebos as a window into the neurochemical mechanisms that connect the mind with the body, belief with experience. ... How does a belief become so potent it can heal? ... Most astonishingly, placebos can work even when the person taking them knows they are placebos.

Maps are for humans, but how do animals, which began navigating millions of years before parchment was invented, manage to find their way around? Do animal (and human) brains contain a map, and if so does it have islands and capes, North Poles and Equators, reference lines and so on? And if they do, where is it, and how does it work? How could a jelly-like blob of protoplasm contain anything as structured as a map? ... These questions have intrigued biologists for many decades, particularly because animals can perform astonishing feats such as navigating their way from the North Pole to the South and back again, like the Arctic tern; or returning home after being transported hundreds of miles away, like the homing pigeon. How animals (both human and non-human) work out their location is just beginning to be understood by brain scientists. There are maps in the brain, as it happens. The properties of these maps, which neuroscientists call ‘cognitive maps’, have turned out to be highly intriguing, and are helping us to understand not just how animals navigate, but also more general principles about how the brain forms, stores and retrieves knowledge.