How does the brain work?

How does the brain work? We have no idea. We are still in the very beginning stages of understanding most of the basics. From a researcher's perspective, it's a very exciting time to be a scientist, because you get to rummage around on the ground floor. But from an overall perspective, most of it is spooky.  

Let me give you some examples of how little we know about how the brain works. We know that you use the left-side of your brain for speech. Under normal circumstances, if you get a stroke on the left side of your brain, your speech can be greatly affected. Depending upon where you got the stroke, it could affect your ability to speak language or your ability to understand language.

There is a little six year old who suffered from something Sturge-Weber syndrome, a catastrophic brain disease. Because he had this disorder, the little guy had to have his entire left hemisphere removed. No left hemisphere, no language. That should have completely destroyed his language ability. Right?


Within two years, the little guy had regained his language abilities entirely. The right side of his brain seemed to have noticed there was a deficit and simply rewired itself to take over talking. Do we understand this?

We do not.

We do not understand how you learn a language of any kind. We don't know how you know how to walk. We don't know how you know how to read. You have a complete map of your body in your head. Actually, you have several maps of your body in your head. Some of them tell you where you are, some of them tell you how to move. One even tells you how to see. We don't know how they coordinate their information. We don't know how it knows its you - and what, if anything, YOU are. Consciousness remains a slippery fish as ever.

So you ask me how the brain works. I am happy to repeat my answer. We have no idea.

Visit brainrules.net to learn about the 12 things we know about how the brain works. These are the Brain Rules.


Theory of Mind

Theory of Mind is about as close to mind-reading as people can get. Most formal definitions go along the lines of the ability to discern the intentions, and motivations of yourself or another person. To develop a Theory of their Mind, hence the term. I think it has two components to it, especially if you're talking about one person trying to understand another's behavioral space. 

First, it's the ability to penetrate inside someone else's psychological interiors and understand the rewards and punishment systems inside that interior.Second, it's the ability to understand at all times that the rewards and punishment systems inside your head are not necessarily the same ones inside your neighbor's head. But he or she is not going to react like you do because he or she doesn't have the same rewards and punishment systems you do.

I joke in the book about calling the following saying John Medina's Second Law of marriage. Here's the saying: what is obvious to you is obvious to you.

I believe Theory of Mind skills are very important in the establishment and maintenance of social relationships. Necessary for success, though I would argue not sufficient. People often confuse it with empathy, but there are important distinctions. You can have terrific Theory of Mind skills and be a Mother Teresa. You read people insightfully and care about what you see. You can also be an SOB with it, too. You can read people insightfully and manipulate them in order to achieve some goal of yours. A dictator may be born with terrific Theory of Mind skills, but they use their talents to squash anybody that gets in their way.


How does memory work?

Watch John Medina talk about how memory works

How does memory work? To begin with, we have to destroy the premise behind the question. We don't just have a memory system - like a computer has a hard-drive. We have various memory systems, each in charge of different types of learning. And they work in a semi-independent way from each other.

Though we've spent a long time looking, we don't actually know much about how these individual systems work. We know even less about how they are integrated.

Let me give you one striking example of how separate the systems are. James McGaugh has worked with a woman for a long period of time called A.J.

A.J. doesn't impress you with dramatic memory abilities when you first meet her. She is a C student. She doesn't have any flashbulb tendencies. Her declarative memory systems - the ability to remember things you can declare, like "Lincoln was the 16th president" appears to be pretty average. If all you looked at were her declarative systems, you wouldn't want to study her at all.

The problem is, AJ has more than just one memory system.

A.J.'s has a memory system that is anything but average.

She has very powerful what we call semantic autobiographical memory. She can remember anything she has ever done, what she has worn for dinner 15 years ago, what flowers she cut and put on the table, and so. Jim has studied her for years and can confirm that she remembers anything of a semantic autobiographical nature. In fact, she is eidetic in this category, photographic, flashbulb like.

Now here we have a conundrum. How come she can't apply that same talent to her schoolwork? The reason is simple. She has two memory systems that work in a semi-independent fashion. She has a great memory for personal experience, She has a poor memory for facts.

You see, memory isn't simple. So when you ask me "how does memory work?" my first response must be "Pray, about what memory system are you talking?"

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The Performance Envelope

Watch the performance envelope video

Though we really don't know very much about how the brain processes information - we have yet to be able to determine why you know your name - to give just one flagrant example - we are not clueless about how the brain works.

We know about its evolutionary performance envelope, for example.

These are the conditions upon which the brain processes information in the best way. The most efficient way. The most accurate way.

The human brain appears to have been designed to solve problems related to surviving in an outdoor setting, in unstable meteorological conditions and to do so in near constant motion.

That's so important I'm going to say it again.

The human brain appears to have been designed to solve problems related to surviving in an outdoor setting, in unstable meteorological conditions and to do so in near constant motion.

Let me drill down on this a little bit.

Its important to understand the human brain is the world's most sophisticated survival organ. It's built to keep its owner alive long enough to pass its owner's genes onto the next generation - a decidedly very Darwinian thing to say. There's the survival stuff.

This magnificent survival organ was forged in an outdoor crucible, probably  and mostly in East Africa. For 99.987% of our time on the planet, we have lived in settings composed of natural elements, starting out in the savannah. We did it under conditions of increasing climatic instability - where our green, wet rainforest that used to inhabit our North African womb increasingly gave way to the not-as-green and not-as-wet savannah.

Because we were hunter-gatherers in an unstable ecological environment, we were moving around almost all of our waking hours. Some estimates put our movement at nearly 12 miles per day. Constant motion.

Those are the conditions under which our brain thrives. We have not escaped the blast radius of our evolutionary predilections forged over millions of years simply because we have - for the last few thousand - been able to live in sedentary cities.

Get the updated and expanded edition of John Medina's NYT bestseller Brain Rules. Learn more at www.brainrules.net


Why we should all take a nap in the afternoon

Why we should all take a nap in the afternoon

Watch the video

It turns out we need a nap during the afternoon. And historically, it seems we've always needed one. There is the Spanish concept of siesta. Italians call it riposo. If you go to China, you are likely many businesses shut down between 11:30 - 2:00 pm. They take a combination lunch and siesta before going back to work. Americans used to call it a power nap, but the research world calls this a nap zone.

We now know that a nap can profoundly influence productivity during the day. Mark Rosekind, a researcher who used to work for NASA - his job was training pilots - actually did an experiment. He allowed his pilots to take a 26-minute nap, then measured their productivity. He found that productivity increased 34% if he allowed his charges to take a nap. He has a really great quote "What other management strategy will improve people's performance 34% in just 26 minutes?" he is famous for saying. 

The research world calls this the nap zone. Other benefits have been found, mostly related to changes in memory performance. Both declarative and procedural memory tasks improve if you take a regular nap. One paper has the delightful title - and remember, this is a research paper "Good sleep, bad sleep! The role of daytime naps in healthy adults. 

I have personal experience with this, and I bet you do too. When I don't take a nap in the mid-afternoon, I typically fight being drowsy from about 1:30 on. If I do take a nap in the mid-afternoon, just a small one, I suddenly get a burst of energy and an alertness that allows me to be productive the entire day. I am pleased to say this anecdotal information has strong empirical support.

Learn more about the importance of sleep

Get the updated and expanded edition of John Medina's NYT bestseller Brain Rules


Brain Rules for Baby: Updated and Expanded!

Brain Rules for Baby has grown! The book now features a chapter on the science of sleep -- the No. 1 question parents ask Dr. Medina.

sleepy baby - new chapter
"How do I get my baby to sleep through the night?"

John Medina introduces the new sleep chapter: video

A note from John Medina

I was hesitant, I admit, about adding a sleep chapter to Brain Rules for Baby. The science about getting your child to go to sleep is fairly wobbly.

But you keep asking me about it. Whenever I lecture, whenever you write me, the question “How do I get my child to go to sleep?” keeps reappearing like a public-television fund-raiser.

I do understand your need for junior to get regular sleep. I know one couple who decided not to have any more children because of the toll their first-born’s sleep habits took on their marriage. The issue can’t get much more important than that.

So I get it. Here is your chapter.

Besides, the professor in me can’t help but want to show you how weak-kneed science can be when it’s yoked to real-world problems. Infant sleep is a terrific illustration of science’s strengths and limitations.

In the Sleepy Baby chapter, you will discover two powerful, opposing ideas about how to get your baby to go to sleep. They’re not mutually exclusive, but they don’t tolerate each other very well. Which one you end up believing depends more on personal preference than peer review. It would be nice if the data were better behaved, but they’re not.

I do provide a solution, however. If you are having trouble getting your child to go to sleep, you will find this chapter useful. And if it solves your problem, feelings of love for your child will once again expand in your heart, like a second Big Bang. That’s the most compelling reason for me to add a new chapter on sleep.

Get the book!

eBook (PDF)
Brain Rules for Baby Audiobook

Just want the sleep chapter? Get it here.

Each ebook comes in PDF format, which you can send to your Kindle or other reading device.

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P.S. Zero to Five by Tracy Cutchlow is due June 17th!


To fans of the Brain Rules books

As John Medina’s editor, I worked closely with him to shape Brain Rules and then Brain Rules for Baby. It’s been a thrill to watch both books climb onto the bestseller lists while getting rave reviews from you. I’m grateful for the books on a personal level as well. I imagine you feel the same way.

Brain Rules for Baby is the one book I asked my husband to read before our baby was born. (I even considered threatening that we couldn’t have a baby until he read it.)

Then our baby arrived.

I wanted to revisit some of the things I’d learned, but suddenly I had no time for long books. And while I understood why doing this or that was beneficial for baby’s brain, I still had questions about how. (Speak 2,100 words an hour to your baby? Seriously? How?) I dug back into the original research. Thus, my new book, Zero to Five, was born. I’d love to tell you about it.

Zero to Five has exhausted new parents in mind

  • how to give baby’s brain a boost—including specific language you can use or actions you can take.
  • bite-sized information in a clean design. Flip the book open to any page and you’ll get something out of it.
  • spiral-bound, so it stays open. You can read while holding baby, or keep your place when you get interrupted two minutes later.
  • anecdotes from my first two years with baby, just to liven things up (I made it—phew!)
  • beautiful photographs of real families. These make Zero to Five a truly special book.

I’m excited to share this book with my fellow Brain Rules fans. It’s due June 17.

Want a sneak peak of the book, free? Click the yellow "free tips" button at www.zerotofive.net.

Tracy Cutchlow is the editor of the bestselling books Brain Rules for Baby and Brain Rules. As a journalist, she has worked for MSN Money and the Seattle Times. She lives in Seattle with her husband and daughter.

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Brain Rules: Updated and Expanded!

The second edition of Brain Rules is here! You made it a bestseller. Now we’ve made it even better, with a fresh edit and a new chapter on how music affects the brain.

Each ebook comes in PDF format, which you can send to your Kindle or other reading device.

We also have great new videos with Dr. Medina to share in the coming weeks. Watch to find out why he decided to write a chapter on music and the brain.


Interview with John Medina

Many parents are concerned about the sleep patterns of their children but in some cultures (Argentina, Spain), staying up late seems not to be a problem. Finally, is there any impact of bedtime or sleep pattern on babies and toddler’s cognitive development?

The most important factor appears to be establishing a consistent bedtime rhythm, regardless of what schedule you follow.

There is room for variation. Different people have different internal clocks – under partial genetic control - regardless of culture. These differences begin to appear in childhood. Some kids turn out to be natural night-owls, for example, and seem to be at their cognitive peak at night (we call them late chronotypes). Others show peaks in the morning (we call them early chronotypes) – and there are all shades in between. What chronotype your child possesses is important for parents to determine - and for kids to follow. Getting the proper amount of regular sleep certainly influences positive cognitive development. But what “proper” means may depend on what child you are talking about.

Several studies showed the benefits of co-sleeping, but some articles also highlight the fact that frequent awakenings during the night can generate stress for babies. Finally, do we know what is the global impact of this practice on sleep quality?

There are pros and cons to cosleeping and the current state of research gives no clear recommendation. There is no permanent damage done if you cosleep with them. There is no permanent damage done if you do the tried-and-true Cry It Out protocols. You can say that frequent awakenings not only stress the baby, they also stress the parents. Continuously stressed parents usually don’t make continuously good parents. Whichever style gives the adult more sleep is generally the healthier option.

Of course this has global implications. The less sleep you get, the more susceptible you become to anxiety and depressive disorders. Sleep loss also affects how you age. The global impact of depression and a poor transit through aging is incalculable.

Baby-wearing, with scarves for example, is increasingly used in western societies, but it has been practiced for centuries in other parts of the world. Does this practice have an impact on babies’ psychomotor development? By fostering visual or tactile exploration of the world for example. And do we know if the induced proximity between parents and babies strengthens the attachment?

I know of no studies conclusively determining whether baby-wearing has either a negative or a positive effect on a baby’s psychomotor development. It’s important for kids to move, for sure, but it’s also important they feel safe. And though safety cues are extremely important for a baby, how that is perceived depends on the child. Some babies seem to love scarves. For others, it’s their worst nightmare.

There are a variety of family structures, from nuclear families to multi-generational families. Does growing up in an extended family and multiplying interactions have an impact on children’s learning abilities, language acquisition or social skills?

I am deeply in favor of multi-generational families. The exposure to multiple intellects provides terrific opportunities for kids to hear alternate points of view -  and learn a great deal about navigating social relationships in a safe, loving atmosphere. Provided the family has a safe, loving atmosphere, that’s a net positive intellectual experience

In some countries, at an early age, toddlers spend much more time with their peers than with their parents and are very independent. What can be the impact of this early autonomy on their cognitive development?

Its not about providing autonomy. It’s about providing perceptions of safety, as I mentioned previously.

The reason is that the brain – even a child’s brain - is the world’s most sophisticated survival organ. If the child feels safe in an independent peer-filled environment, their brain development will maximized. And if that happens, I am all for early independent interactions. But not all kids feel safe in an independent peer-filled environment at an early age. Some get that later.  Parents should pay very close attention to what type of baby they have brought into the world, not into what country the child was born - and decide for themselves how much autonomy they can stand.

Conversely, in some cultures, parents are especially present and try to stimulate their babies’ intellectual growth from the very first months. What are the effects of this enhanced involvement on children’s development?

The greatest predictor of intellectual success is the emotional stability of the home - not the presence of toys or devices built to improve infant cognitive development. Most of those products haven’t been tested, and the few that have been tested don’t work very well. One study actually showed it did more harm.

If you want to maximize your child’s intellectual growth, the best thing you can do is to go home and love your partner.