What would learning and other aspects of mental performance look like if they complied with the latest findings in brain research? That’s the question that developmental molecular biologist John Medina explores and answers a dozen ways in Brain Rules. Brain Rules isn’t really a self-help book, each chapter has immediately practical implications and applications for the real world, hence the subtitle: “12 Principles for Surviving and Thriving at Work, Home, and School.”
Medina writes about the brain in a clear, entertaining style that doesn’t require being brainy to grasp. He frequently illustrates the concepts he’s trying to express with colorful anecdotes — and by the end of the fourth chapter, you’ll understand why. Let’s take a walkthrough. Note that this Brain Rules book review only has space to cover the highlights.
Sleep | Rule #1: Exercise boost brain power. Lack of exercise isn’t just unfashionable, it’s unnatural. Our hunter-gather ancestors covered an average of 12 miles on foot a day. The sedentary life of modern students and office workers doesn’t just encourage atrophy of the body, but of the brain. A wide variety of mental tests confirm that subjects who regularly exercise consistently outperform couch potatoes on every measure of cognitive performance: memory, problem-solving, attention, and other faculties.
Exercise helps increase the brain’s supply of oxygen-rich blood, regulate the release of mood-controlling neurotransmitters (serotonin, dopamine and norepinephrine), and stimulates the production of protein called BDNF (Brain Derived Neurotrophic Factor) which acts as a “fertilizer” for the growth of neurons.
Medina cites a study where students who took time away from academic subjects for physical education performed better on academic tests. He also cites examples of executive installing treadmills in their office for use during calls and email (with laptops mounted on them!), reporting increased clarity and focus.
Survival | Rule #2: The human brain evolved, too. What distinguishes the brains of humans from those of primates? This chapter is more theoretical than practical, but still fascinating. The author examines the work of brain researcher Judy DeLoache, who posits a “Dual Representation Theory” to characterize our capacity for abstract reasoning. The theory describes our ability to attribute multiple characteristics and meanings to objects that don’t possess them. A line can stand for the number one, the letter i, the letter l, or a literal line. “Dual” denotes the difference between the symbolic and the literal.
DeLoache tested a girl of 36 months with a dollhouse and a life-size room whose layout was identical. When DeLoache put a toy dog under the couch of the dollhouse living room, then encouraged the girl to go to the “big” living room to find the big version of the dog, she knew to look under the couch. But a 30-month-old girl is unable to make the connection between scales, and has no idea where to look.
The rest of the chapter discusses the physical evolution of our brains: the three successive layers informally called the lizard brain, the mammalian brain and the human brain (the cortex). Also discussed is the social evolution of human teamwork that compensates for our lack of claws, fangs, wings and fur to protect us from the slings and arrows of nature.
Wiring | Rule #3: Every brain is wired differently. A microprocessor doesn’t modify itself physically when it “learns” (stores) new information. But neurons swell, split and sway as neurotransmitters pass between them during learning activity. Learning literally rewires the brain. Concert violinists, for instance, are observed to have much denser growths of neurons in the hemisphere that controls their left hand, in charge of fingering, than the opposite hemisphere that controls the right hand, in charge of bowing. Darwin observed that the brains of wild animals were 15 to 30 percent larger than their domesticated counterparts exposed to a far less complex environment.
The rate of neural growth seems to match the intensity of real-world learning. At birth, babies have about the same number of connections as adults, but by three years of age, some regions have two the three times the number of connections. By eight, these connections are gradually reduced to adult numbers. The pattern repeats itself one last time from puberty through young adulthood.
Where the brain stores certain types of information, like language, and when these areas mature varies between individuals. Our school system works from the premise that children of the same age “should” be ready for the same curriculum, but about 10 percent of students do not have brains suffiently wired to read at the expected age. Medina offers suggestions for bringing learning and brain development in synch, like interactive software that tests the student’s reading competencies then adaptively tailors exercises to strengthen weak spots.
Attention | Rule #4: We don’t pay attention to boring things. A college lecture is about 50 minutes long, but when asked directly, students will admit that their attention begins to wander after the first 10 minutes. How do we hold attention? Medina cites the work of Michael Posner’s theory of attention when focuses on three facets, or “networks”: the Arousal Network, which monitors the sensory environment for unusual activities; the Orienting Network, for getting our bearings in response to a unique stimulus (Where did that sound come from?); and the Executive Network, for determining the next course of action.
Of the many testable predictions about brain function that have emerged from Posner’s model, Medina focuses on four: (1) that emotional events get our attention, (2) that we process the meaning or gist of a situation before individual details, (3) that the brain is incapable of multitasking (a single task interrupted takes 50 percent longer to complete), and (4) that the brain needs a break from continuous input. The 10-minute threshold is a good starting point for such a break.
Medina began structuring is college lectures in 10-minute modules. He would use one minute of each segment to covey the gist of what the segment covered, then use the rest of the time to provide supporting details that could easily be traced back to the general concept. Sometimes he would start a segment with an emotional “hook,” like a relevant anecdote, to make sure that he kept his students’ attention. After two or three of these, he found that it was usually not necessary to segment the rest of the lecture in order to keep their attention.
Short-Term Memory | Rule #5: Repeat to remember. In the mid-19th Century, Prussian researcher Hermann Ebbinghaus conducted a 30-year series of experiments in which he tried to memorize a series of nonsense words and three-letter combinations. Methodically recording his retention of each piece of information, he noticed a pattern: repeating information at timed intervals increased its retention. Forgetting occurs over time exponentially, according to a predictable curve, so repeating the information with this “forgetting curve” in mind helps flatten it.
Factual information, like the nonsense words that Ebbinghaus learned, or your driver’s license number, fall into a category called declarative memory. Declarative memory is controlled by the hippocampus, which over time passes information from short-term memory (now called “working memory”) to long-term memory. When the hippocampus is damaged, the brain may not be able to form new memories (think of the movie Memento). The other category, non-declarative memory, involves unconscious systems, like the motor skills used in learning to ride a bike.
Besides repetition, Medina offers a couple of principles for increasing declarative memory. First, make the information being learned more elaborate by introducing more associations. This is one of the reasons why the author would use anecdotes in his lectures. By couching facts in stories, there was a richer network of associations to trigger their recall. In short: give examples.
Second, create learning environments with conditions similar to the context of the material being learned. Medina uses the example of having parents create a “Spanish Room” in their homes, filled with Hispanic artifacts. Their children would use the room to study Spanish, with the rule that only Spanish is to be spoken there.
Long-Term Memory | Rule #6 : Remember to repeat. The process of converting short-term memory traces to long-term memory is called consolidation. New memories send electrical signals shooting down from the cortex to the hippocampus and back up to the cortex, even while we sleep. If the stimulus recurrs for long enough (it can even take years, in some cases), the hippocampus cuts of the neurological conversation and stores the results as a permanent memory trace.
Medina discusses the two main models of memory retrieval explored by researcher: the “library model” and the “Sherlock Homes model.” We use both types, depending on the type of information being retrieved.
Factual information, like our home address, is retrieved through the library model — declarative memories encoded by rote learning. The Sherlock Homes model describes memories that are basically reconstructions of the initial situation (the “crime scene”) based on patchwork evidence. These memories may or may not be reliable. One psychiatrist found that 90 percent of adolescents asked if they had ever been disciplined with physical punishment answered in the affirmative. When the same surveyees were asked the same question years later as adults, only a third said yes.
The importance of repetition outlined in the previous chapter is, well, repeated here. Medina proposes a curriculum for the future in which each subject is delivered in 25-minute modules. After 90 minutes, the first subject would be repeated, and then once again for a third cycle. Each subject matter would be similarly interleaved. Every third of fourth day, the entire day would consist of reviewing the material learned in the previous 72 to 96 hours. That sounds like a lot of review, but in a culture that delivers far more information than students can integrate long-term, we may need to prioritize retention over exposure.
Sleep | Rule #7: Sleep well, think well. Studies in underground facilities removing subjects from environmental factors have shown that the body has a series of internal clocks controlled by different regions in the brain.
Our most fundamental body rhythm results from a continuous conflict of two opposing forces: the circadian arousal system (called “process C”) and the homeostatic sleep drive (“process S”). Process C constantly compels us to wake up, and process S compels us to go to sleep. It is not, as we might think, a simple ebb and flow or energy levels. At mid-afternoon, the curves of the two processes converge, and we experience the post-lunch “dip” in energy that has lead some cultures to institutionalize siestas around them.
Sleep research classifies people into three general categories, or “chronotypes.” 10 percent of the population are “larks,” or early chronotypes, who generally wake up before 6 a.m. and feel most alert around noon. 20 percent of the population are “owls,” or late chronotypes, inclined to wake up after 10 a.m. if allowed, feeling most alert around 6 p.m., and usually wanting to go to bed after 3 a.m. The rest of the population is the third category, falling in a continuum somewhere between larks and owls.
Sleep loss has been shown in test after test to diminish attention, recall, logical reasoning, manual dexterity, and a host of other variables affecting learning and productivity. Since late chronotypes often have to work against the norms of office hours, arranging more flexible schedules might recover a huge amount of lost productivity. The author also recommends more regular naps, or a lease an explicit acknowledgment that naps are needed. 70 percent of Americans who admit to taking naps in the workplace report having to do so on the sly — usually in the back set of their cars.
Stress | Rule #8: Stressed brains don’t learn the same way. In evolutionary terms, humans aren’t equipped to handle chronic stress. Back in the day (eons ago), our stressors were saber tooth tigers, snakes and mudslides — terrifying but brief encounters. The extended stress of doing repetitive labor or managing teams is a relatively new phenomenon. Under acute stress, the hypothalamus signals the adrenal glands to flood the bloodstream with adrenaline and cortisol. An excess of adrenaline stops regulating surges in blood pressure, scaring the blood vessels and, over time, possibly leading to stroke.
Stress hormones called glutocorticoids interfere with the hippocampus’ ability to grow new neurons by overruning BDNF and sometimes killing off hippocampal cells directly. As we’ve seen, a healthy hippocampus is critical to memory and learning. Adults with high stress levels have tested 50 percent worse on cognitive tests (declarative memory and executive function) than low-stress adults.
Many of the author’s proposals for dealing with stress at an institutional level come, oddly enough, from a marriage counsellor. John Gottman is famous for marriage interventions that dropped the frequency and severity of hostile interactions, reducing his clients’ divorce rates by 50 percent. Gottman noticed that initial parenthood was the critical point where marital satisfaction drops by 70 percent and maternal depression increases by 62 percent. Gottman embarked on a long-term study that staged interventions right at the moment of pregnancy.
Even more noteworthy than the effects on the marriages themselves were the effects on the children born into them. Children in intervention groups cried less, had stronger attention-shifting behaviors, responded more evenly to external stressors and, physiologically, had more organized nervous systems than children in control groups.
Sensory Integration | Rule #9: Stimulate more of the senses. Despite the frequent complaints we hear about “sensory overload,” sometimes more is more. Cognitive psychologist Richard Mayer has run learning experiments with three groups: a first group receiving information through one sense (like hearing), a second group through another sense (like sight), and a third group getting the information delivered through a combination of the two senses. The latter group consistently recalls more information on tests than the former two. Mayer has run similar experiments in problem-solving. Groups given multisensory presentations of problems generated 50 to 75 percent more creative solutions than unisensory groups.
Mayer has distilled five principles that guide is observations on multisensory learning: that students learn better with words and pictures than words alone, that corresponding words and pictures should be presented simultaneously rather than successively, that they should be presented near each other rather than far from each other, that extraneous material should be excluded rather than included, and that animation should be accompanied by narration rather than on-screen text.
Vision | Rule #10: Vision trumps all other senses. Sight isn’t just one type of perception. It has the power to frame the rest of our perception. 54 professional wine tasters at the University of Bordeaux given white wine colored with tasteless, odorless red dye described what they tasted as though it were red white (wine tasters traditionally use separate vocabularies for red and white wines).
The eye doesn’t take in images as passively as we once believed. Our retinas actually do quite a bit of low-level visual analysis before sending information along the optic nerve to the brain. Specialized cells within the retina capture individual patterns of light, called tracks, which are like individual movies. Each track is responsible for processing one attribute of an image, like an object’s color, its outline or its movement. Up to a dozen tracks are assembled into a single visual impression.
Vision is by far our dominant sense. Half of the cortex is devoted to processing sight, even filling in our blind spot — the retina’s optic disk. We should see two black holes permanently in our field of vision, but the brain seems to provide us with a composite image. Medina gives many examples of the brain’s ability to manufacture visual illusions, from experiments on amputees who “see” their “phantom limbs” in the mirror to the dreams we experience every night.
The practical application of this visual dominance, or “pictorial superiority effect” (PSE), has been demonstrated repeatedly in teaching and learning. Studies have shown that when information is presented orally, people usually remember about 10 percent when tested 72 hours later, compared to 65 percent when pictures are added.
Gender | Rule #11: Male and female brains are different. The structural differences between men’s and women’s brains aren’t very controversial. In certain areas, the cortex is fatter in women than in men. More prominent differences lie in the limbic system, particularly in the amygdala — which controls the generation of emotions and the memory of them. This region is larger in men, and tends to communicate primarily with the right hemisphere. Female amygdalas normally chat with the left hemisphere.
The link between structural and behavioral differences, as you might expect, gets pricklier. Researcher Larry Cahill showed slasher films to men and women to see, using fMRI, how their brains reacted under acute stress. In men, the amygdala in the right hemisphere would light up, and in women, the left. The right hemisphere tends to remember the gist of an experience, while the left hemisphere tends to remember detail. Women typically had better recall of the film’s details when tested a week later. Medina suspects that the stereotype of women being more “emotional” than men stems more from the fact that women respond to and remember more details of emotionally charged events then men, making discussions of those events more robust.
Women tend to use both hemispheres when speaking or processing verbal information, and have thicker cabling between to the two sides. This extra faculty can be a double-edged sword depending on who women are communicating with, since women often communicate by implication that’s obvious to other women, but not necessarily to men. Men hearing the question, “Are you hungry?” are less likely to pick up on the implicit request — “I’m hungry, let’s eat” — than to answer the question literally. Women regard the questioner and his or her dispostion as integral to the question itself.
Exploration | Rule #12: We are powerful and natural explorers. Children love to test reality. So much so that the so-called terrible twos seems to make a theme out of defying authority to discover the consequences. Babies constantly play with objects to test their physical properties: what happens if they’re thrown, dropped, tasted or broken. Over time, these experiments become more deliberate, with children beginning to form hypotheses about what will happen if they do X. At 18 months, for example, they tend to discover “object permanence,” realizing that if they cover an object, it doesn’t disappear; it’s still there when they uncover it.
Exploration occurs through experimentation and emulation. Stick your tongue out at a baby, and if you wait, the baby will return the gesture. Later in childhood, emulation graduates to complex role playing, like Cowboys and Indians. Emulation can also occur internally. When a researcher monitored the brain activity of a monkey when the researcher picked up a raisin (something the monkey had done before), the monkey’s brain reproduced the specific firing pattern of “mirror neurons” used to pick up the raisin himself.
While we never fully stop exploring, it’s clear that for most of us, childhood is the golden age of exploration. How can we extend this reality-testing mindset into adulthood? One way is to simply block time for it. Google is renowned for allowing their employees 20 percent of their time to work on whatever projects they choose. 50 percent of the company’s products, like Gmail and Google News, came from this “20 percent time.”
Medina proposes a “medical-school model” learing environment for other fields of endeavor. Medical students usually walk through a working hospital on their way to class, then begin their internship by in third year, spending half of their time learning on the job. This exposes students to the practice and the people they have to deal with in the real world. Medical schools also expose students to all of the unknowns in the field that are subjects for ongoing research in which the students may participate. Imagine a computer science curriculum where students interned at software firms, learning to deal with coworkers, clients and project managers as well as code.
I’m a big fan of behavioral research that attempts to square itself with what we know about the brain. Getting facts straight about the brain has a lot practical value. If you’re a late chronotype, for instance, it would be better to spend your time working later than waking up earlier. Instead of trying to flash flood your brain with cramming sessions, spaced repetition would be easier and more reliable. There are plenty of other possible examples, but the main point is that it’s better to understand how to brain operates in order to work with it rather than against it. Brain Rules may be a more useful starting point than a self-help book.
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