PDF Summary:Brain Rules, by John Medina

Our brains are uniquely complex information processors, yet most people know little about how they work. In Brain Rules, John Medina writes that when we understand how our brains have evolved, we can use their natural impulses and tendencies to our advantage, improving our thinking and learning in all aspects of our lives.

John Medina is a molecular biologist who focuses on psychiatric disorders. Medina wrote this book in order to help the general public understand in a simple, accessible way how brains work and how the functions of the brain affect how we interact with the world. In this guide, we discuss the 12 rules he’s identified that summarize the brain’s core functions, abilities, and limitations. We also offer ways to apply Medina’s principles in your daily life and discuss scientific and cultural ideas related to his brain rules.

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Category 3: How a Brain Perceives Stimuli

According to Medina, understanding our brain’s responses to sensory stimuli helps our learning, work performance, and happiness. Medina writes that we learn best when we use more than one sense, that vision is the most important sense, and that we’re hardwired to respond to music.

Rule 8: We Learn Best When Using Multiple Senses

In this chapter, Medina contends that using more than one sense at a time improves our learning.

Medina argues that our brains evolved to absorb and make sense of numerous sources of information at the same time, and have developed that capacity so effectively that they actually work best when doing so. We can see this in the fact that our brains better understand and react to different senses when using more than one:

• When we use one sense, others are automatically activated. For example, when we taste something, we might also imagine we smell it, even if the food item has no actual smell.
• When we use one sense, others are actually improved: For example, when we’re trained to hear a doorbell while simultaneously seeing a flash of light, we’re able to hear the doorbell at lower decibels.

(Shortform note: That senses activate and improve one another is dramatically illustrated in the phenomenon of synesthesia, a condition in which a person’s senses are activated by each other in unexpected ways. For example, a person with this condition (it’s estimated that 1 in 90 people has it) might see the color blue when she hears the number three. Though uncommon, synesthesia is a clear demonstration that our senses are hard-wired to work together.)

Medina writes that because our brains are more highly activated and are functioning more optimally when processing multiple senses at once, we can absorb information best when we use more than one sense to do so. Research backs this up: When people learn new information in several ways—for example, learning a language by reading it, listening to it, and watching a movie in it—they retain that information better and for longer.

(Shortform note: Many educators are aware of the efficacy of multisensory learning as a way to improve cognition, and they incorporate techniques based on it into their lessons. For example, teachers may have students who are learning letters to write them out using their hands in shaving cream while saying them out loud—thus engaging the senses of vision, hearing, and feel to help them learn.)

Rule 9: Vision Is the Dominant Sense

Medina argues that vision leads and influences all the other senses, shaping our perception of the world and influencing our learning and memory.

He notes that about half of the brain is dedicated to perceiving and interpreting vision. Because it takes up so much more space in the brain than other senses, vision can overrule other sensory input. Thus, if we receive contradictory information from multiple senses, vision tends to win out.

(Shortform note: The tendency of vision to override other senses, even when inaccurate, is called the Colavita visual dominance effect. While most people experience this effect, research shows that people with autism spectrum disorder may experience the reverse—in one study, hearing overrode vision for autistic subjects, even though vision overrode hearing for subjects without ASD. This “reverse Colavita effect” shows that, despite established patterns, many people process information differently.)

Visual Aids Improve Learning

Medina notes that vision’s dominance also extends to learning and memory. We remember just about anything better when there’s a visual component, so Medina recommends using visual aids to improve learning. Importantly, he notes that visual aids do not include text, which the brain processes differently than pictures.

(Shortform note: Experts advise that in addition to using visual aids to help teach, educators be sure to explain the context for those visual aids—exactly how an aid relates to the information the students are learning, what elements are important, and what elements are irrelevant. For example, if you use Civil-War-era props when studying that time period, analyze how each one sheds light on the habits of people at that time.)

Rule 10: We’re Wired to Respond to Music

Medina argues that playing and listening to music can notably improve cognition. He describes several areas of cognitive function that may be positively affected by participating in or listening to music.

Music leads to improved auditory skills. Medina cites several studies noting that musicians score higher on tests involving identifying subtle differences between sounds—including in speech.

(Shortform note: A recent study shows that piano lessons help children to differentiate between pitches, an important part of language processing.)

Music leads to improved language skills. Studies show that children who study music see improvements in language skills, both spoken and written.

(Shortform note: Since music helps language processing, it also helps children learn how to read and learn language. Studies show that music lessons may even be more effective than additional reading lessons.)

Music leads to improved social skills. Infants exhibit improved social skills when participating in music, such as increased smiling, laughing, and waving to others.

(Shortform note: Studies show that, for children with poor social skills, taking group music lessons improves prosocial behaviors like sharing and helping others. Children also show more positive attitudes toward their peers.)

Music leads to improved emotional skills. According to Medina, studies show that children who played musical games during school have increased empathy for others, as opposed to children who played non-musical games or no games at all. Practiced musicians are also better at detecting emotion in others’ voices.

(Shortform note: Research shows that music education helps children to recognize emotions in images and texts, and can help children to express their emotions.)

Category 4: How a Brain Thinks, Part 1

Medina argues we can improve our learning and performance by understanding how the brain pays attention, keeps focus, and creates and retrieves memories.

Rule 6: Multitasking Doesn’t Work

Medina argues that the better we’re able to focus on something, the better we’re able to learn it and remember it. This is because when we pay attention to more than one thing—when we multitask—we divert our attention from any one task over and over again. Each time we divert our attention and then subsequently refocus our attention, we have to reacquaint ourselves with the task—we have to recall where we left off, the details, our plans for our next steps, and so on. This takes an enormous amount of brain power and results in inefficiencies. Thus, by attempting to focus on two tasks at once, you lessen your ability to complete either. Medina advises that you can be more productive and focused, then, by completing one task at a time.

How to Stay Focused, Instead of Multitasking

As Medina notes, when you multitask, you lose your focus, since your attention is redirected again and again. If you frequently multitask and struggle to pay attention to a single task, here are a few recommendations:

• Pick a few times of day to check email, messages, and/or social media. These all pose frequent distractions, so it can be helpful to determine specific times to check these instead of refreshing them throughout the day.

• Remove distractions from your environment. If you still find yourself checking your phone, your email, or social media frequently, try moving your phone to a different room and blocking distracting websites.

• If your environment is still distracting, leave it. If your workspace has numerous distractions and you need to focus intently on a project, pick a different space with less distractions.

• Do the most difficult, or most important, task of your day first. By doing this, you complete the most focus-intensive work of your day early, so there’s less pressure to finish it later.

Rule 7: The Brain Needs to Form, Retrieve, and Forget Memories

Medina writes that we can strengthen our memories through repetition, and therefore boost our learning.

To form memories, and therefore, to learn from experiences, the brain goes through a complex process that starts with encoding, which is when our brain processes and stores sensory information.

There are two major types of encoding, automatic and effortful processing, based on how easy or difficult it is to make a memory.

Automatic processing is encoding that requires very little conscious effort, usually involving visual stimulus. For example, when you see a memorable movie, your brain will encode it automatically and details of the movie will effortlessly enter your memory.

Effortful processing, on the other hand, requires conscious attention to form a memory. For example, when you study for a test, your brain uses effortful encoding. Effortful encoding can be challenging and requires numerous repetitions before you can easily remember what you learned.

What Happens When Encoding Is Disrupted?

The importance of encoding can be seen when the process is disrupted—for example, when the hippocampus, the area of the brain that encodes short-term memories into long-term ones, is damaged. Hippocampus damage can occur through injury or conditions like Alzheimer’s disease.

When someone’s hippocampus doesn’t function properly, that person develops anterograde amnesia, meaning they can remember very short-term memories but can’t form long-term memories. Thus, while a person with a properly functioning hippocampus might be able to remember their trip to a new bakery a week later, a person with a damaged hippocampus might only remember it for a few minutes.

Techniques for Creating Strong Memories

Medina offers several techniques you can use to strengthen effortful processing and create accurate long-term memories.

• Give complex meaning to your memories. When information has a lot of meaning, it becomes much easier to remember. For example, to memorize a grocery list, you might group the items in terms of what dishes they’ll make. It will be easier to remember this kind of a list rather than a straight, random list.

(Shortform note: One way to give memory meaning, which Barbara Oakley suggests in A Mind for Numbers, is to create a “memory palace.” To do this, imagine a place that you know well—for example, your childhood home. Then fill it with images representing the concept you want to remember. For example, to remember that grocery list, you might imagine a chicken on the staircase or a bag of spinach in the hall.)

• Repeat information over an extended period of time. Spacing out repetition of information is more effective than trying to cram it all in at once. Rather than repeating information 15 times in a row, then, Medina would recommend repeating it once a day for 15 days.

(Shortform note: Research suggests that repeating information without breaks in between is hardly better than not repeating information at all. But if you don’t have time to repeat information periodically over the course of several hours or days, repeating with short breaks in between can be helpful.)

• Reflect and interpret a memory right after it’s formed. This is useful if you have an experience you immediately know you want to remember. Right after an event occurs or you learn new information, discuss the facts of it with someone else. Once you’ve talked about the facts, then discuss your personal interpretation of the event or information.

(Shortform note: If you’re an educator, one way you can use this memory-boosting technique is to quiz students often. This is because it makes students apply what they learned, and consider their interpretations of the information, right after they learn it.)

Category 5: How a Brain Thinks, Part 2

At the end of the book, Medina explores how gender and our instinctive desire to explore influence how our brains function.

Rule 11: Gender Affects Thought Processes

Medina argues that our biological gender affects how we think, learn, and interact with others. He explores this idea in how it relates to behavior and in how it relates to cognition.

Gendered Behavioral Differences

Medina describes numerous behavioral differences between men and women, which he believes affect social and professional relationships. Some research shows that women and girls are generally better at verbal communication than men and boys. Medina notes that this is likely because women tend to use both hemispheres of the brain when speaking and processing verbal information, whereas men tend to use just one.

Gendered Conversational Styles in the Workplace

Linguist Deborah Tannen has found that gendered conversational patterns can benefit men in workplace situations: For example, women may downplay their own contributions, and men may compete to have theirs heard, so people may think their male colleagues have more interesting ideas than their female colleagues. Men may also be seen as more confident than women in the workplace.

Even if gendered conversational styles don’t unfairly benefit men, they can still cause general misunderstandings. For example, men tend to raise issues directly, while women tend to do so indirectly—and if people aren’t on the same page about how to raise an issue, they’re likely to misunderstand each other.

Gendered Cognitive Differences

Medina also notes several cognitive differences between men and women, which he argues affect both thought processes and cognitive health.

One cognitive difference is that men and women tend to respond to stress differently. Research suggests that, when responding to stress, men focus on the general overview of a situation, while women focus on the details.

(Shortform note: Research also shows that men respond to stress with a “fight-or-flight” response, while women respond with a “tend-and-befriend” response. This means that, when faced with a stressful situation, men are likely to either confront or avoid it, while women are likely to look for comfort.)

Men and women also tend to be susceptible to different psychological health issues. Men may be more susceptible to intellectual disabilities, schizophrenia, antisocial behavior, alcoholism, and drug addiction. On the other hand, women may be more susceptible to depression, anxiety, and anorexia.

(Shortform note: Most researchers believe that a combination of biological and cultural factors explain why men and women are susceptible to different mental disorders. Men and women have different hormones, which impact our mental health. Yet aspects of culture that affect gender, like discrimination and gender roles, can also cause harm to mental health. Scientists note that much more research is needed to better understand how biology and culture can create different mental health outcomes for men and women.)

Rule 12: We Learn by Exploring

Medina argues that we have an instinctive, strong desire to explore that drives us to learn about the world throughout our lives.

Exploring and Childhood Development

Medina notes that babies are born with intense curiosity and demonstrate early use of the scientific method. Babies are able to explore and test their surroundings. Their explorations roughly follow the steps of the scientific method: They observe, form hypotheses, experiment, and draw conclusions. We can see this in their earliest attempts to imitate others, which teach them about cause-and-effect and prompt them to run experiments: If I clap, will Mom clap back? As they get older, they test out objects with their hands, mouths, eyes, and so on, to figure out what the object is made of and what it can do. And finally, they discover that other people have different desires than them, and they test these desires by pushing boundaries—learning from an early age how to cooperate within a society.

(Shortform note: Others have spotted the similarities between a child’s exploration and the scientific method, some going so far as to say not only are children small scientists, but that scientists are merely big children. In fact, they point out that the inventor of the modern scientific method, John Dewey, was inspired to outline the steps of the method by watching how children play.)