MACLEAN'S How We Think
BY ROBERT SHEPPARD For hours at a time, psychologist Steven
Pinker subjects some of 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, 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 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 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 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 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 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 "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. |