Young Children's Exposure To Audible Television
Has Implications For Language Acquisition And Brain Development
ScienceDaily (June 2, 2009) — In a
new study, young children and their adult caregivers uttered fewer
vocalizations, used fewer words and engaged in fewer conversations when in the
presence of audible television. The population-based study is the first of its
kind completed in the home environment, guided by lead researcher Dimitri A.
Christakis, MD, MPH, director of the Center for Child Health, Behavior and
Development at Seattle Children's Research Institute and professor of
pediatrics at the University of Washington School of Medicine.
"We've known that television exposure during infancy is associated with
language delays and attentional problems, but so far it has remained unclear
why," said Christakis. "This study is the first to demonstrate that
when the television is on, there is reduced speech in the home. Infants vocalize
less and their caregivers also speak to them more infrequently."
The study looked at infants aged two months to four years old; a total of 329
children were studied. The children wore a small, business card-sized, two ounce
digital recorder on random days monthly for up to two years. A specially
designed vest with a chest pocket held the recorders at a specific distance from
the mouth, and captured everything the child said and also heard during
continuous 12 to 16 hour periods. The recorders were removed only for naps,
baths, nighttime sleep and car rides. A speech identification software program
processed the recorded files to analyze sounds children were exposed to in their
environment, as well as the sounds and utterances they made.
Measurements in this study included adult word counts, child vocalizations,
and child conversational turns, defined as verbal interactions when a child
vocalizes and an adult responds to them vocally (or vice versa) within five
seconds.
The study found that each hour of audible television was associated with
significant reductions in child vocalizations, vocalization duration, and
conversational turns. On average, each additional hour of television exposure
was also associated with a decrease of 770 words the child heard from an adult
during the recording session. This represented a seven percent decrease in words
heard, on average. There were significant reductions in both adult female and
male word counts. From 500 to 1,000 fewer adult words were spoken per hour of
audible television.
"Adults typically utter approximately 941 words per hour. Our study
found that adult words are almost completely eliminated when television is
audible to the child," added Christakis. "These results may explain
the association between infant television exposure and delayed language
development." Christakis further adds that this may also explain
attentional and cognitive delays, since it has been posed that language
development is a critical component of brain development in early childhood.
For purposes of this study, subjects were excluded if they had any diagnosed
language delay, or if the primary language spoken at home was not English.
Children served as their own experimental controls, meaning that the natural
variation within each child's daily television exposure was compared for each
child, looking at the amount of vocalizations and conversational turns that each
individual child experienced, on both their high-television days as well as
their low-television days. The recordings did not distinguish between foreground
television and background television; no determinations were made about whether
the children or adults were actively watching the television or it was simply
audible in the environment.
The American Academy of Pediatrics' Committee on Public Education
(Pediatrics, 2001) specifically recommends against screen time for children
under two years of age, urging more interactive play in its place.
"Since 30 percent of American households now report having the
television always on, even when no one is watching, these findings have grave
implications for language acquisition and therefore perhaps even early brain
development," added Christakis. "Audible television clearly reduces
speech for both infants and their caregivers within the home, and this is
potentially harmful for babies' development. There is simply nothing better for
early childhood language acquisition than the spoken and imitated words of
caregivers, and every word counts. Television is not only a poor caregiver
substitute, but it actually reduces the number of language sounds and words
babies hear, vocalize and therefore learn. We are increasingly technologizing
infancy, which may prove harmful to the next generation of adults."
Recorders, vests and software from the LENA Foundation provided data
collection. LENA is a language environment analysis system designed to provide
parents, clinicians and researchers with information about the language
environment of infants and toddlers.
Tips and resources for parents and caregivers include the following
recommendations:
