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Maclean's Online How We Think Canada's Steven Pinker challenges the accepted wisdom of how the human brain works BY ROBERT SHEPPARD For hours at a time, psychologist
Steven Pinker subjects some of America's brightest university students to
a battery of real and imaginary words. What is the past tense of "slace"
or "plip"? he asks. What is the past of to "see" with your eyes, or to
"saw" with a saw? See-saw-sawed. Confronted with something as mighty as a
word, the human mind takes all of a quarter of a second to store it (for
most people in the rear of the left hemisphere) and then ship it out for
processing to word-fetching memory banks or the rule-making generating
stations in different parts of the brain. Asked to deal with made-up
words, the mind shows an equal dexterity in drawing meaning and
grammatical correctness, barely missing a beat. Pinker can see this happen
on a computer screen: his subjects are contemplating the peculiarities of
the English language while the magnetic activity in their brains is being
measured to within one-hundredth of a second. The results of all these
mental gymnastics send brightly coloured tracers slacing across a
computerized map of the brain in a real-life game of Pong.
From his perch as a professor of cognitive neuroscience at the
prestigious Massachusetts Institute of Technology, the Montreal-born
Pinker has a touching faith in the brainwaves of 19-year-olds. "As a
scientist, I have been trained not to trust anything unless it can be
verified in the lab on the brains of rats or sophomores," he says with the
dry wit that has made him a sought-after guest at high-table seminars, on
The New York Times commentary pages, even on TV talk shows. But the
45-year-old Pinker is more than just a walking one-liner or even the
latest academic superstar. He is at the epicentre of a growing group of
mostly youngish researchers in different fields who are using the latest
imaging technology to map the biology of the brain and, with the audacity
that only science can muster, dare to explain how the mind works.
Canadian scientists have long been at the forefront of research into
the brain, partly because of the pioneering efforts at the Montreal
Neurological Institute during the 1940s and '50s. Alan Evans, a top MNI
researcher, is part of an international team that recently showed the
brain developing and reorganizing its real estate for much longer in life
than was previously thought. In Hamilton, McMaster University psychiatrist
and neuroscientist Sandra Witelson, like Pinker a graduate of Montreal's
McGill University, made waves last year for revealing the tantalizing
structural mysteries of Einstein's brain.
But respected as these and many other researchers are in their own
fields, none has achieved Pinker's profile. Maybe it is because of the
rock-star looks that can seem a tad out of place in today's academia. More
likely it is because of a wide-ranging intellect that makes Pinker that
rare breed -- a serious scientist with a common touch and a genius for
confronting orthodoxy and standing his ground in academic food fights.
In person and on a lecture stage, Pinker is endearingly Canadian:
polite, soft-spoken, attentive to what others say. His strength is that he
doesn't just study language, he wields it like a sword, cutting through
pomp and political correctness to explain everything from the origins of
grammar to the evolutionary underpinnings of guilt, pornography,
infanticide, even humour.
But there is another side to Pinker, too: quirky, non-conformist,
competitive, perhaps to be expected for a big-brained primate who has
spent the past 23 years in Boston's Harvard-MIT nexus, a notorious bastion
of catty intellectualism. His very public feud about the evolutionary
basis of the mind with Harvard paleo-biologist Stephen Jay Gould --
another elegant popularizer -- was part of a debate that went on for weeks
in The New York Review of Books before ending up on the front page of The
Boston Globe. There is also a hint here of the angry young man as
scientist: "Every idea in the book may turn out to be wrong," Pinker wrote
in the introduction to his 1997 best-seller, How the Mind Works. "But that
would be progress, because our old ideas were too vapid to be wrong."
In his corner office at the fringe of MIT's sprawling,
neoclassical-style campus across the Charles River from a tony residential
section of Boston, Pinker has an ideal spot to absorb all that modern
science has to offer on the brain, from linguists like the celebrated Noam
Chomsky, a couple of buildings away, to one of the world's largest centres
for the study of robots and artificial intelligence. "Language is my
work," he says. "The rest" -- referring to his theories of how the mind
works -- "is kind of a hobby." It is a "hobby," mind you, that nearly
earned him the Pulitzer Prize two years ago and has him dangerously close
to becoming a cultural icon, the New Age guru for the machinery of
thought.
His three most recent books on language and the mind have been popular
best-sellers. Top British and American newspapers and magazines have
published admiring profiles. Not bad for a studious Montrealer, the eldest
of three siblings, all professionals, who describes himself as an
"erstwhile '60s radical" come late to the party. Before McGill, he went to
Montreal's celebrated "hippie college," Dawson, from 1971 to 1973. "But I
was hardly a hippie," he says. Pinker didn't do drugs or drink but tripped
out on the excitement of exploring what made people tick. "When I
discovered you could bring someone into a lab and ask questions about
human behaviour," he says, "that's when everything fell into place." And
he's been grooving on that ever since.
Is the human mind a clean slate on which is writ the sum total of an
individual's life -- upbringing, schooling, personal relationships, the
myriad cultural refinements that flow from things like television or good
books? That may be the dominant view. Or is it, in effect, a giant
computer, preprogrammed in large measure from humanity's earliest
endeavours -- and with a good number of those early hunter-gatherer quirks
still intact? Pinker thinks that's the case, though he is quick to note
that this does not mean human behaviour is preprogrammed as well.
Scientists may yet find a specific location in the brain for jealousy or
adultery. But those behaviours will be played out "among many mental
modules," Pinker says, not to mention the chessboard of other people's
behaviour and expectations.
"Now, for more and more things that you and I actually talk about in
conversation, we are starting to find a home in the brain," says Pinker.
He would include concepts like social intelligence (the ability to impute
motive and desires to other people), a sense of justice, and romantic love
as being hard-wired in large measure in the brain through hundreds of
thousands of years of evolution. Some scientists claim to have located a
brain site for humanity's moral compass. (It's in the ridge of grey matter
just behind the eyeballs. The sociopath's brain would have a shrunken
version.) Want to know why teenagers won't do their term projects until
the very last minute? According to some neuroscientists, it is because
their frontal cortex, the place for future-based decision-making, is still
being formed.
These beliefs are not universally held. Critics wonder if Pinker and
other researchers are being seduced by a technology that reveals
biological responses that may have nothing to do with the questions being
asked. Magnetic resonance imaging (MRI), one of the new, relatively
unobtrusive techniques for taking pictures of the brain's activity, is
notoriously complex. Researchers find that repeating a test does not
always produce the same response each time: the mind, it seems, likes
novelty.
Still, the mere fact that researchers at scores of centres around the
world are fixing similar cognitive functions in well-documented locations
suggests very strongly that the human brain is built in a particular way.
And regardless of the academic quarrelling, there is no disputing that a
decade of increasingly sophisticated examination has produced a concept of
the brain, especially regarding such key areas as memory, development,
gender differences, language and emotion.
McGill's MNI, for example, recently won a $22-million grant to
establish the world's first neuroanatomy atlas for children. It will use
data from eight hospitals and research centres in North America to
correlate brain development with behaviour. "Within 10 to 15 years, there
is going to be a huge amount of evidence setting out the biological basis
for variations in behaviour," says McMaster's Witelson. "That's where the
field is going."
That's where Pinker is heading as well. How the Mind Works is an
ambitious, 660-page tome that seeks to explain everything from artificial
intelligence to hotheadedness. His latest offering, Words and Rules, is
ostensibly about the quirky nature of regular and irregular verbs in the
English language. But in Pinker's hands, the subject becomes much more --
a way of understanding the double-barrelled approach with which the mind
seems to process information.
Other scientists are finding this, too, notably Michael Petrides at
McGill. He argues there are (at least) two distinct levels, both in the
prefrontal cortex, for processing thought. And they are not based on the
thing that is being processed, whether it is a place or an object, but on
the abstractness of the thought itself. For Pinker, language is made up of
both memory for sounds and symbols, and instinctual, built-in rules that
generate grammar and meaning. The two processes appear to stem from
different places in the brain and, Pinker suggests, may be a model for how
the mind deals with other important cognitive functions.
It is a view that has reignited the nature versus nurture debate. It
sees the human brain as a system of organs that has evolved to include
specialized functions, with their own software, to deal with some of the
basic imperatives of life: language, reproduction, kinship, social
responsibilities, fear and emotion, an awareness of place. Complicated
ideas are built out of simple ones, just as complex sentences are built
from simple rules and sounds.
Some of the brain's software -- say, sexual jealousy or a disgust at
eating insects -- may be out of date, left over from life on the African
plains eons ago. But it may still play a part in how we live our lives or,
in some instances, in how we try to heal the brain from injury or
psychiatric disorder. Pinker, who quotes extensively from the work of
evolutionary psychologists, nonetheless says it is naive to think the
modern mind works simply according to evolutionary dictates. Rather than
nature versus nurture, he says, it is better to think of the brain as a
biological machine that combines both -- constantly, maybe even in the
nanosecond it takes to fire a neuron -- in a kind of see-saw, slip-"slace"
battle between the new and the genetically acquired.
MOOD AND THE MIND
Helen Mayberg makes people sad. An otherwise cheery and polite
neurologist at the Rotman Research Institute in Toronto, Mayberg is
unapologetic about what she does: "If you take normal, healthy people and
ask them to read something they've written about a traumatic event in
their lives, within four minutes they become tearful." And within that
period of time, the brain undergoes a remarkable transformation.
Emotion is among the least studied of cognitive functions. But modern
imaging research is starting to show two distinct patterns. One is that
the brain biology of people experiencing transient sadness -- such as
Mayberg's test patients -- is similar to that of others with deep-seated
depression. That suggests that sadness and depression have much in common
and that some minds just aren't able to switch out of that state. The
other pattern is that intense emotion sets up a tug of war between the
ancient limbic system and the more modern cortex, especially the frontal
lobes where thinking and planning take precedence. As sadness or
depression progresses, the limbic system goes into overdrive, firing its
neurons while the thinking part shuts down. "The brain may be forced to
pick and choose," says Mayberg. "You can't sneeze and keep your eyes open
at the same time. That's hard-wired. Maybe it's the same with emotion."
Depressed people, she says, have tremendous difficulty concentrating even
on ordinary tasks. Healthy people can snap out of sadness as the thinking
part of the brain fights back.
Some suggest that emotion evolved in the first place because of a need
to back up promises and threats: the intellect ceding partial control to
the passions. Who will believe the threat of deadline unless an editor is
willing to throw a tantrum now and then? Fear seems to set up a mental
battle between the quick-response and the more analytical mechanisms in
the brain. And fear may in fact be several emotions. Phobias about
physical things or social scrutiny respond to different drugs, suggesting
they belong to different neural networks.
HOW MEMORY WORKS
The good news is that memory is cached in many more parts of the brain
than was previously thought. Researchers are also finding at least some
capacity for the mind to reorganize itself and relearn important functions
after stroke or injury. The bad news: you still can't tell your brain to
remember something on command. "Intention itself is a relatively feeble
method of committing a name or a fact to memory," laughs the University of
Toronto's Endel Tulving, at 73 the grandfather of memory research in this
country. The brain, it seems, has its own rationale for deciding what
should be remembered and what shouldn't. Some of it may be purely
chemical: Princeton University scientist Joe Tsien has made a "smarter"
mouse by adding a chemical receptor to its genetic makeup to strengthen
the synapses, the sites where two nerve cells touch. The result: the mouse
has a better memory for fear and reward.
Ten years ago, scientists felt that almost all memory was situated in
the hippocampus, a seahorse-shaped organ embedded in the centre of the
brain. Now, because of brain imaging techniques, they are seeing the
machinery of thought operate in a much more far-flung manner. Imaging
shows the brain works harder -- has more active areas -- when processing
words than when dealing with visual images, even though visual scenes are
by far more easily remembered.
Tulving says there are probably at least five memory systems, each with
its own properties and processes. Short-term or working memory is located
in the frontal cortex behind the forehead. It is the part of the brain
that enables us to follow conversations, to remember telephone numbers (on
a good day) and, some say, to act as a clearinghouse for decision-making
-- sending sensory information to other parts of the brain for deeper
cogitation. New research is showing that working memory has its own
specific brain chemistry.
Long-term memory would include procedural memory (how to ride a bike,
type or speak); priming memory (recognizing objects and words); semantic
memory (general knowledge of the world through books, television and
common experiences like standing in the rain to know it's wet); and
episodic memory (direct personal experiences). Of these, Tulving says,
only episodic has to do with the past and fits the common notion of memory
being dredged up or being "remembered." The others are more a biological
process of action and reaction: a face triggers a name, which triggers a
complex set of greetings and interaction, some of which -- if the brain
decides it's relevant -- gets stored for future use.
SIZE AND INTELLIGENCE
Sandra Witelson, a demure woman who has held the preserved brain of
Albert Einstein in her hands and studied it for science, takes a moment to
ponder whether people with larger brains are smarter. "That may be the
case," the McMaster neuroscientist says cautiously. But more important
than overall size is structure, or the size of specific regions --
Einstein's brain being a case in point. The brain of the man who upended
300 years of scientific tradition is of average male size, not out of line
with any of the 64 other brains in Witelson's eclectic collection. But it
had two unusual characteristics. One is that the parietal lobes, the grey
matter just back of the ears where problem-solving and visualization
occur, are about a centimetre -- or 15 per cent -- wider than a standard
brain's. The other is that Einstein's Sylvian fissure, the crevice that
flows through the area in the brain servicing mathematical reasoning and
visualization, has a noticeably unique route along the surface, leaving
these two areas much more densely packed together. "Every brain is
different just like every face is different," says Witelson. "But we have
never seen anything like this before."
Einstein's rerouted fissure may be a developmental quirk that occurred
at birth. Or it may be a genetic or environmental twist that will
eventually show up in other individuals with highly developed spatial
skills. Witelson is eager to test that hypothesis. Brain imaging is
starting to pick up other features that are unique to certain individuals
-- an enlargement of the auditory cortex in those with perfect pitch, for
example -- and is continuing to define the structural differences between
the sexes.
Broadly speaking, the brain is divided into two hemispheres, with
language skills located primarily in the left, and spatial skills in the
right. Many studies have shown that women's language skills are more
equally distributed between the two halves -- a distinct advantage if
stroke or injury affects the left hemisphere. And recent studies are
showing that the differences in the brains of men and women extend right
down to the cellular and chemical level, even to the way cells in parts of
the cortex are packed and organized.
In March, a German team using brain-imaging techniques reported that
men escaped a virtual-reality maze much faster than women -- in an average
of two minutes and 22 seconds compared with three minutes and 16 seconds.
More intriguing, perhaps, they discovered that the sexes often used
different areas of the brain to navigate: men relied on the left
hippocampus, a memory region that specializes in spatial tasks; women
tended to use more of the parietal and prefrontal areas, which are linked
to visual clues and reasoning. Oddly, perhaps, the hippocampus in women
tends to be larger, a refinement that may explain why women suffer less
memory loss with Alzheimer's disease.
Men, however, have a larger corpus callosum, the neural pathway that
links the two hemispheres. "The research is suggesting that the
relationship between anatomy and cognition is different in each sex," says
Witelson. "It is like two different automobiles. Each has a motor, a
steering mechanism and brakes. But one is a Volvo and the other is a Lexus
-- and I'm not for an instant implying which sex is which."
THE MATURING BRAIN
In the first three years of life, the human brain is a veritable
factory of neural development. Trillions of synaptic circuits that will
last a lifetime are being formed. Just to grow the brain, young children
use twice as much energy in their heads as adults, who carry about all the
cares of the world. But scientists are now discovering that the brain can
grow and reorganize itself, within limits, past puberty and possibly well
into adulthood, depending on the demands put on it. A British study
released in March showed that the brains of cab drivers ranging in age
from 32 to 62 had experienced a "relative redistribution of grey matter"
in the memory-focusing hippocampus. The researchers attributed the change
to having to learn to navigate the labyrinthine streets of London.
"Simply put, the brain is a riot of functional changes," says the MNI's
Evans. What's more, the maturing brain, awash in distinct stages of
chemical and hormonal development, is like nature's wild garden: the grey
matter grows more synapses than it needs, then spends part of its
development "pruning" or leaving aside areas that are not put to use.
Between 6 and 15 are the peak language years when the left (language)
hemisphere fills out. Some scientists believe the window shuts at about 11
or 12, at the onset of puberty, when learning new languages becomes much
more difficult. Studies of children with damaged left hemispheres show
that their language skills can be reorganized, within limits, on the right
side before puberty; after that the right hemisphere has pretty well
settled into a different way of ordering its world.
The brains of teenagers are definitely a work in progress. Hormones
push the limbic system, where raw emotion is seated, into overdrive. At
the same time, the frontal cortex, where cool-headed decision-making takes
place, is still trying to get its act together. This back and forth may
explain why teenagers can't seem to choose between talking on the phone or
doing their homework when a term paper looms; and why social situations
and insults become so important: they are still sorting out the social
signals. One study showed adults and teenagers images of faces contorted
in fear. All the adults recognized the emotion; many teens didn't. Scans
also showed the adults and teens used different areas of their brains
during the experiment.
THE LANGUAGE INSTINCT
When an almost three-year-old says, "I breaked the window," she is
saying what all kids do at that age. "Everyone," says Steven Pinker,
"without fail." And there's the rub. Children do not hear a verb like that
from their parents -- they deduce them, says Pinker, from rules that
follow a logic buried in their brains from time immemorial. That logic --
a language instinct akin to learning how to walk -- allows them to hear a
few thousand sentences, then produce an almost unlimited number of their
own. Children soak up language "not quite like a sponge," says Pinker.
There is a lot of symbol crunching involved, a lot of deduction. Some
linguists argue that instinctual rules are the basis of all language.
Others say there are no rules, just patterns of association that children
pick up on. Pinker says both apply.
Irregular verbs such as to be, to go or to do (there are 164 in
English) were once generated by rules that have been bastardized over the
ages. Now, they must be remembered. Imaging research shows different parts
of the brain light up for rule-based regular words as opposed to memorized
irregular ones. Unfortunately for some researchers, the areas in use vary
from study to study. But illness offers a better clue. Patients in the
early stages of Alzheimer's have trouble remembering words, but can still
speak in fluent, mostly grammatical sentences; people with Parkinson's
disease, on the other hand, have the opposite tendency -- an indication of
two distinct pathways in the brain.
It is possible that instinctual rules evolved -- they can be found in
every language, Pinker believes -- only for language. But perhaps they
also evolved to help humans think in broad categories. Someone can be
"grandmotherly" without ever having borne children; "game" can mean
anything from solitaire to hockey. Thought is not sifting, at incredible
speeds, through a mental file cabinet of stereotypes. Nor is conversation.
They occur naturally, by deduction, by prediction, by cranking through a
chain of implications where one notion triggers another. And they occur by
reading the subtle clues that humans give off, whether it is in the face,
the tone of voice or the curious inflections at the end of sentences that
can vary from culture to culture. That, says Pinker, is how the mind
works.
Related links:
Massachusetts Institute of Technology Department of
Brain and Cognitive Sciences at MIT Unofficial Steven Pinker Web Page Stanford University Mapping the Mysteries of the Mind
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