DVDs sold to help babies talk could be hindering their speech

Too much use of the programmes can hinder the word power of very young babies, they say.

A study shows infants who regularly watched baby DVDs and videos understood fewer words than those who did not. DVDs and videos such as Baby Einstein and Brainy Baby, which cost around £18, are increasingly being bought by parents to help give their children a boost.

But experts say they may harm a child's natural development during the critical early stages when they are acquiring vocabulary.

A study by the University of Washington and Seattle Children's Hospital Research Institute compared the word power of infants watching baby DVDs and videos, educational and non-educational material or adult TV programmes.

Baby DVDs held back the acquisition of vocabulary for those aged eight to 16 months, says a report today in the U.S.

Journal of Pediatrics. Frederick Zimmerman, an associate professor of health services at the University of Washington, said: 'There is no clear evidence of a benefit coming from baby DVDs and videos and here is some suggestion of harm.

"The more a child watches baby DVDs and videos the bigger the effect. The amount of viewing does matter. The best policy is safety first. Parents should limit their exposure as much as possible."

The researchers conducted interviews with more than 1,000 families with a child born in the previous two years.

TV, DVD and video viewing was divided into four categories including baby DVDs and videos, educational programmes such as Sesame Street and noneducational shows including Bob the Builder. Adult TV shows included The Simpsons, Oprah and sports programmes.

The researchers found no positive or negative effects on any of the infants from viewing any of the categories - except the baby DVDs and videos.

For every hour per day spent watching baby DVDs and videos, they found, infants aged eight to 16 months understood an average of six to eight fewer words than those who did not watch them.

Researcher Andrew Meltzoff said: 'The results surprised us but they make sense.

"There are only a fixed amount of hours that young babies are awake and alert.

"If "alert timeî is spent in front of DVDs and TV instead of with people speaking "parenteseî the babies are not getting the same linguistic experience. Parents are the baby's first and best teachers.

"Watching attention-getting DVDs and TV may not be an even swap for human interaction at this very young age."

The researchers believe the content of baby DVDs and videos is different because it has little dialogue and disconnected scenes that cannot be easily described. In contrast, educational programmes are tested to meet the developmental needs of pre-school children.