多對小孩說話，有助腦部發展
摘錄自：天下雜誌 經濟學人電子報 2014/3/14
2014-03-05Web only
作者：經濟學人
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| 圖片來源：flickr.com/photos/martinaphotography/ |
家長越常對小孩說話，小孩的智能發展也就越好。1995年，堪薩斯大學的哈特（Betty Hart）和萊斯利（Todd Risley）完成了長達10年的研究；他們發現，家長在小孩3歲時對他們所說的字詞數量，與小孩9歲時的學術成就呈現相關。
由此觀之，將小孩在4歲時送進幼稚園，已經來不及彌補家庭教育的差距；所幸，科學界對孩童字詞發展的理解已經越來越深入。史丹佛大學的菲納德（Anne Fernald）發現，差異早在小孩3歲之前就已經出現；就算只有18個月大，出自弱勢家庭的嬰兒，表現還是落後出生優渥家庭的小孩數個月。
此問題似乎具累積性；等到小孩2歲之時，兩個群組在語言處理能力和字詞上的差距已達6個月。此外，菲納德博士的研究顯示，直接對小孩說出的字詞才能建造他們的字詞能力，把小孩放在電視機前、或是讓他們聽大人聊天，都沒有同樣的效果。
哥倫比亞大學的諾伯（Kimberly Noble）指出，語言差距亦反映在大腦語言處理區的結構。小孩出生時約有1000億個神經元，而神經元間的連結會在1歲前快速增加；這些連結會決定腦部運作的能力，以及腦部學習的事物。等到小孩3歲時，腦中約有1,000兆個連結，小孩的經驗也會持續決定要強化或減少哪方面的能力。就是這個有點難以逆轉的漸進過程，形塑了小孩的人生軌道。
還好，家長不常對小孩說話這個問題不難解決。第一步就是告訴家長；許多志願參加研究的家長，並不知道只要對小孩說話，就能幫助小孩發展。還有些輔助工具，例如語言環境分析（LENA）裝置等，讓家長得以監控並改善他們的說話模式。兒科醫生蘇斯金（Dana Suskind）的研究發現，LENA再加上一次家庭拜訪，在6周後就能讓小孩每小時聽到的字詞數量增加32％。
本財務年度，美國已有30個州增加了學前教育預算；這當然是好事，但也無法處理菲納德、諾伯、蘇斯金等人發現的早期發展差異。而這個差距的重要性，似乎高過了4歲那一年的學前教育。（黃維德譯）
©The Economist
Newspaper Limited 2014
The Economist
Child development
In the
beginning was the word
By The Economist
From The Economist
Published: March
05, 2014
Feb 22nd 2014 |
CHICAGO | From the print edition
How babbling to
babies can boost their brains.
THE more parents
talk to their children, the faster those children's vocabularies grow and the
better their intelligence develops. That might seem blindingly obvious, but it
took until 1995 for science to show just how early in life the difference
begins to matter. In that year Betty Hart and Todd Risley of the University of
Kansas published the results of a decade-long study in which they had looked at
how, and how much, 42 families in Kansas City conversed at home. Dr Hart and Dr
Risley found a close correlation between the number of words a child's parents
had spoken to him by the time he was three and his academic success at the age
of nine. At three, children born into professional families had heard 30m more
words than those from a poorer background.
This observation
has profound implications for policies about babies and their parents. It
suggests that sending children to "pre-school" (nurseries or
kindergartens) at the age of four—a favoured step among policymakers—comes too
late to compensate for educational shortcomings at home. Happily, understanding
of how children's vocabularies develop is growing, as several presentations at
this year's meeting of the American Association for the Advancement of Science
showed.
One of the most
striking revelations came from Anne Fernald of Stanford University, who has
found that the disparity appears well before a child is three. Even at the
tender age of 18 months, when most toddlers speak only a dozen words, those
from disadvantaged families are several months behind other, more favoured
children. Indeed, Dr Fernald thinks the differentiation starts at birth.
She measures how quickly
toddlers process language by sitting them on their mothers' laps and showing
them two images; a dog and a ball, say. A recorded voice tells the toddler to
look at the ball while a camera records his reaction. This lets Dr Fernald note
the moment the child's gaze begins shifting towards the correct image. At 18
months, toddlers from better-off backgrounds can identify the correct object in
750 milliseconds—200 milliseconds faster than those from poorer families. This,
says Dr Fernald, is a huge difference.
Mind the gap
The problem seems
to be cumulative. By the time children are two, there is a six-month disparity
in the language-processing skills and vocabulary of the two groups. It is easy
to see how this might happen. Toddlers learn new words from their context, so
the faster a child understands the words he already knows, the easier it is for
him to attend to those he does not.
It is also now
clear from Dr Fernald's work that words spoken directly to a child, rather than
those simply heard in the home, are what builds vocabulary. Plonking children
in front of the television does not have the same effect. Neither does letting
them sit at the feet of academic parents while the grown-ups converse about
Plato.
The effects can be
seen directly in the brain. Kimberly Noble of Columbia University told the
meeting how linguistic disparities are reflected in the structure of the parts
of the brain involved in processing language. Although she cannot yet prove
that hearing speech causes the brain to grow, it would fit with existing
theories of how experience shapes the brain. Babies are born with about 100
billion neurons, and connections between these form at an exponentially rising
rate in the first years of life. It is the pattern of these connections which
determines how well the brain works, and what it learns. By the time a child is
three there will be about 1,000 trillion connections in his brain, and that
child's experiences continuously determine which are strengthened and which
pruned. This process, gradual and more-or-less irreversible, shapes the
trajectory of the child's life.
Fortunately,
taciturnity can be easily fixed. Telling parents is the first step: many who
volunteered themselves and their children for study did not know they could
help their babies do well simply by speaking to them.
There are tools
that can help, as well. One such is a Language Environment Analysis (LENA)
device. It is like a pedometer, but keeps track of words, not steps, by
analysing the speech children hear. It was originally developed as a prop for
research, but parents kept asking for the data it recorded and researchers thus
realised it could also serve as a spur. Parents use it to monitor, and improve,
their patterns of speech, much as a pedometer-wearing couch potato might try to
reach 10,000 steps a day, say.
A recent study by
Dana Suskind shows how promising this approach is. Dr Suskind is a paediatric
surgeon in Chicago. She got interested in the field while monitoring children
whom she had fitted with artificial cochleas, to treat deafness.
Her new study
shows that the use of a LENA device, combined with a one-off home visit to give
parents advice, produces a 32% increase in the number of words a child hears
per hour after six weeks. Dr Suskind's Thirty Million Words Initiative (named
after Dr Hart's and Dr Risley's original finding) is now using LENA devices and
weekly home visits to improve the linguistic diet of children in Chicago.
Parents are taught to make the words they serve up more enriching. For example,
instead of telling a child, "Put your shoes on," one might say
instead, "It is time to go out. What do we have to do?"
Other groups are
trying similar approaches. In Providence, Rhode Island, Angel Taveras, the
mayor, has started a project that uses LENA devices to improve the vocabularies
of children in pre-school. Meanwhile, in Chicago and several other places,
nurses who visit mothers' homes to give them advice on health and nutrition
also encourage them to chat to their children and read to them aloud. Such
interventions are effective and not particularly expensive.
In January Barack
Obama urged Congress and state governments to make high-quality pre-schools
available to every four-year-old. He is knocking on an open door. This
financial year 30 states and the District of Columbia have increased spending
on pre-schools. Nationally, this amounts to an increase of 6.9%.
That is a good
thing. Pre-school programmes are known to develop children's numeracy, social
skills and (as the term "pre-school" suggests) readiness for school.
But they do not deal with the gap in much earlier development that Dr Fernald,
Dr Noble, Dr Suskind and others have identified. And it is this gap, more than
a year's pre-schooling at the age of four, which seems to determine a child's
chances for the rest of his life.
©The Economist
Newspaper Limited 2014
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