readings> how a child's mind is born
The brain is a
machine that has to build itself. The genes produce a generalised lump
of tissue equipped with a few reflexes. Each new-born babe then has to
learn how to see, feel and think – how to be conscious -
through its interactions with the world.
It is tempting to think of the mind as simply blossoming into being. We
are born, we open our eyes, and we start to be conscious. But a
baby’s brain has to learn how to make sense of its world.
Consciousness – as we know it in all its sharply focused,
meaning-imbued and introspective glory – is a skill that must
be mastered in well-defined stages.
Learning to be conscious actually begins in the womb. By 14 weeks, a
foetus has a brain. It squirms to the touch. Stress hormones surge
through its body if it is pricked, suggesting it feels pain. But such
responses must actually be reflexive – a
“knee-jerk” response from spinal nerves or the
brainstem – because the higher brain is still an unconnected
mass of cells.
By six months however, the brain is wired up enough for the
foetus to hear, smell, taste and even blink when bright light shines
onto its mother’s stomach. Experiments show that new-borns
can recognise music and voices they heard during the pregnancy. So
while the womb may seem a watery twilight world, significant learning
is already taking place.
But then comes birth. Now the brain really can get going. A new-born
brain is still expanding at a phenomenal rate, adding a quarter of a
million neurons every single minute. However this rampant growth is
also rather random. Connections are made willy-nilly. The connections
are also immature, having no fatty sheathing to insulate them. Nerve
traffic flows spasmodically across a jumble of pathways.
So what does the infant brain experience? Tests suggest that it is
indeed a “blooming, buzzing confusion”. Electrical
recordings of a baby looking at simple patterns, like different sized
stripes, show that its brain responds with much the same surge of
neural firing to one as another. It sees, but it does not see in a way
that says this experience of a stripy pattern is distinct from that
one.
It also takes in information slowly. Not much sense is made of
one muddy experience before it is having to make sense of the next. For
the first few months, perhaps the only strongly differentiated
experience is for the mother’s face and breast. All else
beyond this charmed circle is elusive, shape-shifting, murk.
But oh how quickly this changes. The baby fast acquires habits of
perception – the memories and expectations that make sense of
the world. And to build these into the brain, brain growth actually has
to go into reverse. Connections are severed and cells die to prune back
the forest of connections to some more efficient shape. During the
first few years of life, we lose fully half our brain cells. That
amounts to millions of neurons and billions of synaptic connections
evaporating every day!
But the result is a brain that has grown to fit its world,
discovering through experimentation which are the connections that can
deliver focused impressions. The brain builds in the wiring that can
see stripes of all sizes and can tell a cat from a dog, orange from
red, and make the millions of other sharp perceptual distinctions that
adults take for granted as the very ground of conscious experience.
So even the circuits of perception are developed through a
child’s interaction with the world. And every parent has seen
the equivalent struggle as a baby learns how to make its hands grasp
and its body balance. From this platform, the full complexity of adult
consciousness then has to be built up in a series of stages.
The two great pioneers of a developmental view of the mind were the
Swiss psychologist, Jean Piaget and the Russian psychologist, Lev
Vygotsky.
Piaget stressed the role of the individual in bringing about his or her
own intellectual development. A sharp observer of children, Piaget
noticed that there was a natural succession of lessons to be learnt.
For instance, a child has to begin by establishing some very general
expectations about the world. At about eight months, a baby will have
learnt enough to know that when a toy is hidden by a blanket, the toy
still lies underneath. This is easy to demonstrate as it is only at
this age that a baby will show surprise if the blanket is lifted and
the toy has been magicked away.
Later the child has to master more sophisticated expectations, such as
that when a tall thin glass of water is poured into a short fat glass,
the quantity of water remains the same despite the fact the apparent
levels are now different. Like miniature scientists, children are
always experimenting – banging objects, messing about with
them – and so gradually developing mental schemas or rules
that make their worlds an understood place.
The development of a sense of self is one of these important lessons.
While youngsters can recognise themselves in mirrors from as young as
12 months, Piaget felt children are “egocentric”
until the age of five or six. It takes quite some time for them to
realise that other people may see and feel life from quite a different
point of view. But as they come to form a “theory of
mind”, to be able to put themselves in another’s
shoes, this in turn strengthens their own perception of selfhood. They
can be objective about their own subjective existence. It also paves
the way to mature emotional reactions and moral judgements.
Vygotsky differed from Piaget in placing more stress on the role played
by society and language in shaping the minds of young children.
Vygotsky pointed out that not only are all children born into the same
physical world – and so will learn the same basic sensory and
perceptual lessons – but they are also born into well-defined
cultural worlds and so will assimilate critical intellectual lessons
from their interactions with these as well.
Of course, speech itself has to be learnt and is a tool of rationality
and self-regulation. Vygotsky showed how children learn to express
their thoughts in words, first through talking to themselves and others
aloud, and then internalising such thinking as a private
monologue – a habit of wrestling ideas from the self.
But Vygotsky argued that many other things that we consider to
be second nature to our conscious selves are actually the
internalisation of socially-evolved ways of thinking. So
“attitudes” like how to be loyal, how to be in
love, how to be socially productive (or romantically rebellious), are
learnt from ideas that have developed within our cultures.
The interactionist theories of Piaget and Vygotsky are largely
common-sense. Babies are born and then develop increasingly complex
minds, each new set of mental skills paving the way for further levels
of elaboration.
But what has recently astonished psychologists is to find that the
human brain seems genetically adapted to a lifetime of such learning.
Until a short time ago, it was assumed the brain gets all its growth
and pruning over in the first few years of life. The last parts of the
brain to harden into shape were believed to be the language centres
which reach maturity at around six or seven.
Yet brain scans have shown that the very highest levels of the
brain – those that have most to do with planning, social
judgement and emotional control – have a sudden surge of
growth just before puberty and then are gradually pruned to
shape during the teenage years and even early adulthood.
What this appears to mean is that evolution expects us still to be
learning important intellectual lessons at this age. The necessary
plasticity has been designed in so that we can assimilate a socialised
mindset in a gradual, step by step, fashion. If the behaviour of an
adolescent seems immature (or interestingly experimental as a teenager
would see it), then this is literally so. The human mind was meant to
develop through a prolonged process of adjustment before finally
arriving at a state of happy and wise fit with its environment.
is a baby's brain really unwired?
The claim that human babies are born with largely unwired
brains seems
contradicted by two stunning observations. Experiments suggest that
children can recognise their mother’s face the same day they
are born.
When shown slides of their mother and a stranger, and allowed to keep
one slide up by sucking faster on a pacifier, new-borns would favour
the mother.
A new-born just a few hours old can also mimic
your facial expressions! If you pull a happy, sad or surprised face, it
can produce a rough copy. Stick out your tongue or glance away and it
will do the same.
Yet neuroscientists know that the cortex –
the wrinkled grey matter that is supposed to be the seat of such
intellectual feats – has hardly any connections at this
stage. So what
babies do should be impossible.
The answer it seems is
that new-borns are relying on the older “reptilian”
core of the brain
which does mature while they are still in the womb. The ability to
recognise a familiar face is due to an ancient midbrain structure, the
superior colliculus, which was the original visual centre in reptiles.
While the ability to copy expressions is credited to another primitive
structure, the amygdala, the highest emotion centre in reptiles.
Neuroscientists
take this to mean that when new-borns produce these feats, they are
doing so at a reflexive, unthinking level. It takes the development of
the cortex for them to do the same thing at a knowing and meaningful
level. Significantly, the ability to mimic is actually lost as soon as
the cortex starts to gain control. And children develop
“stranger
anxiety” at six months once they begin to see the world at a
fully
conscious level.
the evolution of adolescence
Contrary to popular belief, our genes nudge rather than
instruct our mental development. And they can do this in extremely
subtle ways. It has recently been discovered that the higher brain
areas of teenagers are still plastic, still open to learning. Indeed,
some researchers say the whole of adolescence is a life-stage unique to
Homo sapiens.
Barry Bogin, a University of Michigan anthropologist, points out that
apes go straight into adulthood. They reach adult size and are
immediately ready to reproduce. But humans have at least a four year
gap between sexual maturity – when the sex hormones
begin to flow – and actual prime reproductive age. Curiously,
boys’ and girls’ bodies also follow quite different
courses. Boys become fertile and hormone driven at about 13, yet their
bodies stay puny and sexually unappealing to females until a spurt in
muscle development during their late teens. Girls, on the other hand,
grow a womanly shape at puberty, yet are surprisingly unfertile until
their late teens.
“Despite all the news stories about 12 year olds having
babies, it’s actually quite rare. We find that across all
cultures the average age of first birth is usually around
19,” Bogin says.
Bogin’s theory is that this genetically-evolved pattern of
body development allowed early humans time to master the intricacies of
adult social relations. Girls needed to look like women before they
were so they would be included in the routine of baby care, allowing
them to pick up the essential skills of mothering.
Boys would have needed the sexual drive and aggression of an
adult male while still looking like an unthreatening kid so they could
learn the correct adult role “without getting their teeth
knocked in.” In contrasting ways, the genes nudged
adolescents towards learning the right lessons.
Of course this was all back in the days we lived in caves and ate bison
steaks. Today’s teenagers probably have enough on their hands
just mastering the intricacies of teenage culture!
wolf children
The importance of other humans to our mental development is
graphically illustrated by the story of Amala and Kamala, two Indian
girls stolen as babies by wolves and raised in their jungle lair. In
1920, a local missionary rescued the children, by then aged three and
five. They ran around on all fours, only ate raw meat, showed no facial
expressions and preferred the company of his dogs. Their hearing, smell
and eyesight seemed preternaturally sharp. But they never learnt to
speak, walk or shake-off their wolf-like ways.
It appears that their brains had already been formed by their early
immersion in a wolf’s world and it was too late to master the
feelings, language, thoughts and self-awareness of a human being. Their
story had no happy ending. The younger sickened and died soon after her
rescue. The elder died of typhoid at 16, house-trained but still more
animal than human in mind.