Brain Rules (Updated and Expanded)

Brain Rule #7
Repeat to remember.

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•
The brain has many types of memory systems. Declarative memory
follows four stages of processing: encoding, storing, retrieving, and
forgetting.
•
Information coming into your brain is immediately fragmented and sent
to different regions of the cortex.
•
The more elaborately we encode a memory during its initial moments,
the stronger it will be.
•
You can improve your chances of remembering something if you
reproduce the environment in which you first put it into your brain.
•
Working memory is a collection of busy work spaces that allows us to
temporarily retain newly acquired information. If we don’t repeat the
information, it disappears.
•
Long-term memories are formed in a two-way conversation between the
hippocampus and the cortex, until the hippocampus breaks the connection
and the memory is fixed in the cortex—which can take years.
•
Our brains give us only an approximate view of reality, because they mix
new knowledge with past memories and store them together as one.
•
The way to make long-term memory more reliable is to incorporate new
information gradually and repeat it in timed intervals.

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sensory integration
Brain Rule #8
Stimulate more of the senses.

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EVERY TIME TIM SEES the letter 
E
, he also sees the color red. He
describes the color change as if suddenly forced to look at the world
through red-tinted glasses. When Tim looks away from the letter 
E
, his
world returns to normal, until he encounters the letter 
O
. Then the world
turns blue. For Tim, reading a book is like living in a disco. For a long time,
Tim thought this happened to everyone. When he discovered this happened
to 
no
one—at least no one he knew—he began to suspect he was crazy.
Neither impression was correct. Tim is suffering—if that’s the right word—
from a brain condition called synesthesia. It’s experienced by perhaps one
in 2,000 people; some think more.
Synesthesia appears to be a short circuiting in the way the brain
processes the world’s many senses. But it also provides a strong clue that
our sensory processes are wired to work together. In one of the strangest
types of synesthesia—there are at least three dozen—people see a word and
immediately experience a taste on their tongue. This isn’t the typical
mouthwatering response, such as imagining the taste of a candy bar after
hearing the word “chocolate.” This is like seeing the word “sky” in a novel
and suddenly tasting a sour lemon in your mouth. A clever experiment
showed that even when the synesthete could not recall the exact word, he or
she would still get the taste from a general description of the word. Even
when the brain’s wiring gets confused, the senses still attempt to work
together.
Here’s another way we know the brain likes sensory integration.
Suppose researchers show you a video of a person saying the surprisingly
ugly syllable “ga.” Unbeknownst to you, the scientists have turned off the
sound of the original video and dubbed the sound “ba” onto it. When the
scientist asks you to listen to the video with your eyes closed, you hear “ba”
just fine. But if you open your eyes, your brain suddenly encounters the
shape of the lips saying “ga” while your ears are still hearing “ba.” The

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brain has no idea what to do with this contradiction. So it makes something
up. If you are like most people, what you actually will hear when your eyes
open is the syllable “da.” This is the brain’s compromise between what you
hear and what you see—its need to attempt integration. It’s called the
McGurk effect.
But you don’t have to be in a laboratory to see it in action. You can just
go to a movie. The actors you see speaking to each other on-screen are not
really speaking to each other at all. Their voices emanate from speakers
cleverly placed around the room: some behind you, some beside you; none
centered on the actors’ mouths. Even so, you believe the voices are coming
from those mouths. Your eyes observe lips moving in tandem with the
words your ears are hearing, and the brain combines the experience to trick
you into believing the dialogue comes from the screen. Together, these
senses create the perception of someone speaking in front of you, when
actually nobody is speaking in front of you.
The process of sensory integration has such a positive effect on learning
that it forms the heart of Brain Rule #8: Stimulate more of the senses at the
same time.
A fire hose of sights and sounds
An incredible amount of sensory information comes at us in any given
moment. Imagine, for example, that you’ve gone out on a Friday night to a
dance club in New York. The beat of the music dominates, hypnotic, felt
more than heard. Laser lights shoot across the room. Bodies move. The
smells of sweat, alcohol, and illegal smoking mix in the atmosphere like a
second sound track. In the corner, a jilted lover is crying. You step out for a
breath of fresh air. The jilted lover follows you. All of these external
physical inputs and internal emotional inputs are presented to your brain in
a never-ending fire hose of sensations. Does the example of a dance club
seem extreme? It probably holds no more information than what you’d
normally experience the next morning on the streets of Manhattan.
Faithfully, your brain perceives the screech of the taxis, the smell of the
pretzels for sale, the blink of the crosswalk signal, the touch of people
brushing past. And your brain integrates them all into one coherent
experience.

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You are a wonder. We in brain-science land are only beginning to figure
out how you do it.
It’s mysterious: On one hand, your head crackles with the perceptions of
the whole world—sight, sound, taste, smell, touch—as energetic as that
dance party. On the other hand, the inside of your head is a darkened, silent
place, lonely as a cave. The Greeks didn’t think the brain did much of
anything. They thought it just sat there like an inert pile of clay. Indeed, it
does not generate enough electricity to prick your finger. Aristotle thought
the heart held all the action. Pumping out rich, red blood 24 hours a day, the
heart, he reasoned, harbored the “vital flame of life.” This fire produced
enough heat to give the brain a job description: to act as a cooling device.
(He thought the lungs helped out, too.) Perhaps taking a cue from Aristotle,
we still use the word “heart” to describe many aspects of mental life. Now
we know that one of the brain’s major job descriptions is to handle all of the
inputs that our senses pick up and allow us to perceive the world.
How we perceive something
During the Revolutionary War, the British—steeped in the traditions of
large European land wars—had lots of central planning. The field office
gathered information from leaders on the battleground and then issued its
commands. The Americans—steeped in the traditions of nothing—used
guerrilla tactics: on-the-ground analysis and decision making prior to
consultation with a central command. These very different approaches are a
good way to describe the two main theories scientists have about how the
brain goes from sensing something to perceiving it. Imagine the sound of a
single gunshot over a green field during that war.
In the British model of this experience, our senses function separately,
sending their information into the brain’s central command, its sophisticated
perception centers. Only in these centers does the brain combine the
sensory inputs into a cohesive perception of the environment. The ears hear
the rifle and generate a complete auditory report of what just occurred. The
eyes see the smoke from the gun arising from the turf and process the
information separately, generating a visual report of the event. The nose,
smelling gunpowder, does the same thing. They each send their data to
central command. There, the inputs are bound together, a cohesive

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perception is created, and the brain lets the soldier in on what he just
experienced.
The American model puts things very differently. Here the senses work
together from the very beginning, consulting and influencing one another
quite early in the process. As the ears and eyes simultaneously pick up
gunshot and smoke, the two impressions immediately confer with each
other. They perceive that the events are occurring in tandem, without
conferencing with any higher authority. The picture of a rifle firing over an
open field emerges in the observer’s brain. Perception is not where the
integration begins but where the integration culminates.
Which model is correct? The data are edging in the direction of the
second model. There are tantalizing suggestions that the senses do help one
another, and in a precisely coordinated fashion. We’ll talk about them in a
couple of pages.