Brain Rules: 12 Principles for Surviving and Thriving at Work, Home, and School

BRAIN RULES. Copyright © 2008 by John J. Medina.

All rights reserved. Printed in the United States of America. No part of this book may be used or reproduced in any manner whatsoever without written permission except in the case of brief quotations embodied in critical articles or reviews. Requests for permission should be addressed to:

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Edited by Tracy Cutchlow
Designed by Greg Pearson

Library of Congress Cataloging-In-Publication Data is available upon request.

ISBN-10: 0-9797777-0-4 ISBN-13: 978-0-9797777-0-7

10 9 8 7 6 5 4 3 2 1

To Joshua and Noah

Gratitude, my dear boys, for constantly reminding me
that age is not something that matters
unless you are cheese.



Rule #1: Exercise boosts brain power.
Our brains love motion ~ The incredible test-score booster ~ Will you age like Jim or like Frank? ~ How oxygen builds roads for the brain

Rule #2: The human brain evolved, too.
What’s uniquely human about us ~ A brilliant survival strategy ~ Meet your brain ~ How we conquered the world

Rule #3: Every brain is wired differently.
Neurons slide, slither, and split ~ Experience makes the difference ~ Furious brain development not once, but twice ~ The Jennifer Aniston neuron

Rule #4: We don’t pay attention to boring things.
Emotion matters ~ Why there is no such thing as multitasking ~ We pay great attention to threats, sex, and pattern matching ~ The brain needs a break!

short-term memory
Rule #5: Repeat to remember.
Memories are volatile ~ How details become splattered across the insides of our brains ~ How the brain pieces them back together again ~ Where memories go

long-term memory
Rule #6: Remember to repeat.
If you don’t repeat this within 30 seconds, you’ll forget it ~ Spaced repetition cycles are key to remembering ~ When floating in water could help your memory

Rule #7: Sleep well, think well.
The brain doesn’t sleep to rest ~ Two armies at war in your head ~ How to improve your performance 34 percent in 26 minutes ~ Which bird are you? ~ Sleep on it!

Rule #8: Stressed brains don’t learn the same way.
Stress is good, stress is bad ~ A villain and a hero in the toxicstress battle ~ Why the home matters to the workplace ~ Marriage intervention for happy couples

sensory integration
Rule #9: Stimulate more of the senses.
How and why all of our senses work together ~ Multisensory learning means better remembering ~ What’s that smell?

Rule #10: Vision trumps all other senses.
Playing tricks on wine tasters ~ You see what your brain wants to see, and it likes to make stuff up ~ Throw out your PowerPoint

Rule #11: Male and female brains are different.
Sexing humans ~ The difference between little girl best friends and little boy best friends ~ Men favor gist when stressed; women favor details ~ A forgetting drug

Rule #12: We are powerful and natural explorers.
Babies are great scientists ~ Exploration is aggressive ~ Monkey see, monkey do ~ Curiosity is everything



about the author


GO AHEAD AND multiply the number 8,388,628 x 2 in your head. Can you do it in a few seconds? There is a young man who can double that number
24 times
in the space of a few seconds. He gets it right every time. There is a boy who can tell you the precise time of day at any moment, even in his sleep. There is a girl who can correctly determine the exact dimensions of an object 20 feet away. There is a child who at age 6 drew such lifelike and powerful pictures, she got her own show at a gallery on Madison Avenue. Yet none of these children could be taught to tie their shoes. Indeed, none of them have an IQ greater than 50.

The brain is an amazing thing.

Your brain may not be nearly so odd, but it is no less extraordinary. Easily the most sophisticated information-transfer system on Earth, your brain is fully capable of taking the little black squiggles on this piece of bleached wood and deriving meaning from them. To accomplish this miracle, your brain sends jolts of electricity crackling through hundreds of miles of wires composed of brain cells so small that thousands of them could fit into the period at the end of this sentence. You accomplish all of this in less time than it takes you to blink. Indeed, you have just done it.

What’s equally incredible, given our intimate association with it, is this: Most of us have no idea how our brain works.

This has strange consequences. We try to talk on our cell phones and drive at the same time, even though it is literally impossible for our brains to multitask when it comes to paying attention. We have created high-stress office environments, even though a stressed brain is significantly less productive. Our schools are designed so that most real learning has to occur at home. This would be funny if it weren’t so harmful.

Blame it on the fact that brain scientists rarely have a conversation with teachers and business professionals, education majors and accountants, superintendents and CEOs. Unless you have the
Journal of Neuroscience
sitting on your coffee table, you’re out of the loop.

This book is meant to get you into the loop.

12 brain rules

My goal is to introduce you to 12 things we know about how the brain works. I call these Brain Rules. For each rule, I present the science and then offer ideas for investigating how the rule might apply to our daily lives, especially at work and school. The brain is complex, and I am taking only slivers of information from each subject—not comprehensive but, I hope, accessible. The Brain Rules film, available at
, is an integral part of the project. You might use the DVD as an introduction, and then jump between a chapter in the book and the illustrations online. A sampling of the ideas you’ll encounter:

• For starters, we are not used to sitting at a desk for eight hours a day. From an evolutionary perspective, our brains developed while working out, walking as many as 12 miles a day. The brain still craves that experience, especially in sedentary populations like our own. That’s why exercise boosts brain power (Brain Rule #1) in such populations. Exercisers outperform couch potatoes in long-term memory, reasoning, attention, and problem-solving tasks. I am convinced that integrating exercise into our eight hours at work or school would only be normal.

• As you no doubt have noticed if you’ve ever sat through a typical PowerPoint presentation, people don’t pay attention to boring things (Brain Rule #4). You’ve got seconds to grab someone’s attention and only 10 minutes to keep it. At 9 minutes and 59 seconds, something must be done to regain attention and restart the clock—something emotional and relevant. Also, the brain needs a break. That’s why I use stories in this book to make many of my points.

• Ever feel tired about 3 o’clock in the afternoon? That’s because your brain really wants to take a nap. You might be more productive if you did: In one study, a 26-minute nap improved NASA pilots’ performance by 34 percent. And whether you get enough rest at night affects your mental agility the next day. Sleep well, think well (Brain Rule #7).

• We’ll meet a man who can read two pages at the same time, one with each eye, and remember everything in the pages forever. Most of us do more forgetting than remembering, of course, and that’s why we must repeat to remember (Brain Rule #5). When you understand the brain’s rules for memory, you’ll see why I want to destroy the notion of homework.

• We’ll find out why the terrible twos only look like active rebellion but actually are a child’s powerful urge to explore. Babies may not have a lot of knowledge about the world, but they know a whole lot about how to get it. We are powerful and natural explorers (Brain Rule #12), and this never leaves us, despite the artificial environments we’ve built for ourselves.

no prescriptions

The ideas ending the chapters of this book are not a prescription. They are a call for real-world research. The reason springs from what I do for a living. My research expertise is the molecular basis of psychiatric disorders, but my real interest is in trying to understand the fascinating distance between a gene and a behavior. I have been a private consultant for most of my professional life, a hired gun for research projects in need of a developmental molecular biologist with such specialization. I have had the privilege of watching countless research efforts involving chromosomes and mental function.

On such journeys, I occasionally would run across articles and books that made startling claims based on “recent advances” in brain science about how to change the way we teach people and do business. And I would panic, wondering if the authors were reading some literature totally off my radar screen. I speak several dialects of brain science, and I knew nothing from those worlds capable of dictating best practices for education and business. In truth, if we ever fully understood how the human brain knew how to pick up a glass of water, it would represent a major achievement.

There was no need to panic. You can responsibly train a skeptical eye on any claim that brain research can without equivocation tell us how to become better teachers, parents, business leaders, or students. This book is a call for research simply because we don’t know enough to be prescriptive. It is an attempt to vaccinate against mythologies such as the “Mozart Effect,” left brain/right brain personalities, and getting your babies into Harvard by making them listen to language tapes while they are still in the womb.

back to the jungle

What we know about the brain comes from biologists who study brain tissues, experimental psychologists who study behavior, cognitive neuroscientists who study how the first relates to the second, and evolutionary biologists.

Though we know precious little about how the brain works, our evolutionary history tells us this: The brain appears to be designed to solve problems related to surviving in an unstable outdoor environment, and to do so in nearly constant motion. I call this the brain’s performance envelope.

Each subject in this book—exercise, survival, wiring, attention, memory, sleep, stress, sense, vision, gender, and exploration—relates to this performance envelope. Motion translates to exercise. Environmental instability led to the extremely flexible way our brains are wired, allowing us to solve problems through exploration. Learning from our mistakes so we could survive in the great outdoors meant paying attention to certain things at the expense of others, and it meant creating memories in a particular way.

Though we have been stuffing them into classrooms and cubicles for decades, our brains actually were built to survive in jungles and grasslands. We have not outgrown this.

I am a nice guy, but I am a grumpy scientist. For a study to appear in this book, it has to pass what some at The Boeing Company (for which I have done some consulting) call MGF: the Medina Grump Factor. That means the supporting research for each of my points must first be published in a peer-reviewed journal and then successfully replicated. Many of the studies have been replicated dozens of times. (To stay as reader-friendly as possible, extensive references are not in this book but can be found at

What do these studies show, viewed as a whole? Mostly this: If you wanted to create an education environment that was directly opposed to what the brain was good at doing, you probably would design something like a classroom. If you wanted to create a business environment that was directly opposed to what the brain was good at doing, you probably would design something like a cubicle. And if you wanted to change things, you might have to tear down both and start over.

In many ways, starting over is what this book is all about.

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