A new study shows that for every hour spent within earshot of a television, fewer words are spoken by parents to their young children and fewer vocalizations are made by children in response.
"Some of these reductions are likely due to children being left alone in front of the television screen, 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," write researcher Dimitri A. Christakis, MD, MPH, of the University of Washington, and colleagues in the Archives of Pediatrics & Adolescent Medicine.
"Furthermore, given that 30% of households have televisions on all the time, our results beg the question of how many opportunities of child and parent vocalizations are being displaced."
The American Academy of Pediatrics discourages television or video viewing before the age of 2 because this is a critical point in infant language development, which is fostered by interacting with adults.
In the study, researchers analyzed information gathered from 329 2- to 48-month-old children. The children wore digital devices on random days for up to 24 months that recorded everything they heard or said.
The recordings were analyzed by software that categorized the sounds and counted words spoken to the children by adults.
The results showed that each additional hour of television exposure by the child was associated with a decrease in 770 words (7%) that the child heard from an adult during the recording session.
Each additional hour of television exposure among children was also associated with a reduction in the number and length of child vocalizations.
Researchers say these results may explain previous associations between television viewing and delayed language acquisition. But they say the findings also call television programs and DVDs marketed to young children into question.
"These findings must be interpreted in light of the fact that 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," write the researchers.