By the time kids start school,
there are already differences among them in their language abilities. These early differences can have an enormous
impact on their performance in school, because teachers do most of their
instruction by talking to kids.
Where do these early differences
come from?
A growing body of evidence
suggests that a huge influence on early language development is the number of
words that children hear as infants and toddlers. The more that parents speak to their infants
and in front of their infants, the better infants get at understanding speech
and learning words.
This issue has been explored in some
previous work that has compared children who grow up in low socioeconomic
status (SES) and high SES homes. An
interesting paper in the November, 2013 issue of Psychological Science by Adriana Weisleder and Anne Fernald
examined this question just within a sample of low SES Spanish speaking homes
in the United States.
They had 19-month-old infants wear
an audio recorder for at least one full day.
Many infants wore the recorder for several days, and the longest
recording day was selected.
Using software, the recordings
were analyzed to identify all of the words spoken in the infants’ presence
during that day. In addition, the
researchers classified the speech by whether it was directed at the infants or
whether it was just speech that the infants overheard.
Both when the infants were
19-months-old and again when they were 24-months-old, the researchers measured
their efficiency at understanding speech.
In these tests, the infants were seated in front of a screen. They saw pairs of pictures displaying common
objects (like a dog or a ball). They
heard the Spanish word for one of those pictures spoken and the researchers
measured how much the infant looked at the picture corresponding to the spoken
word as well as how quickly the infant looked at that picture after the word
was spoken. In addition, at 24 months,
the parents used a checklist to estimate the size of their child’s vocabulary.
Within this sample, there was a
huge difference in the number of words that the infants heard. Some infants heard fewer than 2000 words in a
day, while some heard over 15,000. In
addition, there were big differences in child-directed speech. Some families spoke fewer than 1000 words to
their children in a day, while others spoke over 10,000 words to their children.
The number of words spoken to
children at 19 months was a significant predictor of the child’s vocabulary at
24 months. In addition, the number of
words spoken to children predicted how quickly and effectively children looked
at the picture associated with a word they heard. Statistical analysis demonstrated that the
ease of identifying the words in speech was an important reason why infants who
heard more words had a larger vocabulary at 24-months than infants who heard
fewer words.
This early language experience
compounds itself over time. Not only do
infants who hear lots of words understand language better than those who hear
fewer words, they are also more likely to start vocalizing and speaking words
earlier. When children talk more, adults
talk back to them more often. So, the
early advantage in language ability gets bigger over time.
This research demonstrates the
importance of a rich environment for infants.
Infant brains are developing rapidly, and that brain development is
strongly influenced by what is going on around them. The more that these infants are embedded in a
complex language environment, the more that their language abilities
develop. And that early development
gives them a huge advantage as they start school.
