Adults naturally adjust their speech and eye gaze to help babies learn language.Adults naturally adjust their speech and eye gaze to help babies learn language. (Canadian Press)

Young children and their caregivers use fewer words and share fewer conversations when they're listening to the TV, researchers have found.

In the June issue of the Archives of Pediatrics & Adolescent Medicine, researchers reported that each hour the TV was on was associated with an average decrease of 770 words the child heard from an adult during a recorded session, after adjusting for the child's age.

Tips for parents and caregivers

For babies:

  • Avoid TV for babies under age two. Choose activities that promote language development and brain growth such as talking, playing, reading, singing and enjoying music.

For children over age two:

  • If you allow TV time, choose age-appropriate programs.
  • Involve older children in setting guidelines for what to watch.
  • Use guides and ratings to help, but beware of unproven claims that programs or DVDs are educational. Even cartoons produced for children can be violent or overstimulating.
  • Limit TV time to no more than two hours per day. Less is better.
  • Keep TV off during meals.
  • Set "media-free" days and plan other fun things to do.
  • Avoid using TV as a reward.
  • Turn off TV when a chosen program is over. Don't leave TV on as background filler or while engaging in other activities.
  • When no one is actively watching, turn TV off.
  • Watch TV with your child. Talk about what you see and engage with your child about the content.
  • Keep TVs out of bedrooms.

Source: Seattle Children's Hospital

"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 Dr. Dimitri Christakis, a professor of pediatrics at the University of Washington Medical School.

"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 American Academy of Pediatrics discourages television or video viewing before the age of two, suggesting that parents focus on interactive play to encourage development including acquiring language.

In the study, 329 children aged two months to four years wore digital devices on random days for up to 24 months. The devices recorded everything they heard or said for 12 to 16 hours, without considering whether the adults and children were actively watching TV or if it was just on in the background.

Hours of television were linked with a decrease in the number and length of vocalizations by the child and back and forth conversations between the child and adult, the researcher found.

"Some of these reductions are likely due to children being left alone in front of the television screen," the researchers wrote in the study, "but others likely reflect situations in which adults, though present, are distracted by the screen and not interacting with their infant in a discernible manner."

Previous studies by this research team showed that hearing adults speak and being spoken to are critical ways for infants to learn language, and that adults naturally adjust their speech, eye gaze and social signals to support language acquisition.

"Purveyors of infant DVDs claim that their products are designed to give parents and children a chance to interact with one another, an assertion that lacks empirical evidence," the study's authors noted.

Some of the study's authors work for the LENA Foundation, which paid for the data collection and develops technology for the screening, diagnosis and treatment of language delays and disorders in children and adults.