Parents who think they can compensate or even substitute parental care and physical interaction with brain-training DVDs should reconsider their options, a new study suggests.

Mounting evidence shows that baby training DVDs are not the Holy Grail when it comes to making children smarter. Moreover, they seem to be the cause for which babies that watch them are performing worse than their siblings who don’t come into contact with such educational material.

Training DVDs like "Baby Einstein" and "Brainy Baby" are apparently slowing down the evolution of your child, according to the conclusions of a new study by Frederick Zimmerman and Dr. Dimitri Christakis, from the University of Washington.

Published in the latest issue of The Journal of Pediatrics, the study found that for every hour per day spent watching baby DVDs and videos, infants aged eight to 16 months understood an average of six to eight less words than those who did not watch them.

For toddlers aged 17 to 24 months, the DVDs had neither a positive nor negative effect.

For an industry worth about $20 billion, the conclusions of the research are worrisome, especially when the training DVDs are actually producing more harm than good: for the age category of 8 to 16 months (the age at which language skills are starting to form) the baby-train material had the worst effect.

"The more videos they watched, the fewer words they knew," says Christakis. "These babies scored about 10% lower on language skills than infants who had not watched these videos."

More than a thousand families have been involved in the study, whose aim was to compare the relative influence on kids’ linguistic development of educational DVDs, educational TV programming like “Sesame Street” and non-educational programming like the popular “Oprah” show or “Sponge Bob”.

Learning specific language skills prove to be better when parents interacted physically and affectively more with their little ones, than when they tried to substitute that interaction with DVDs.

During an interview with Newsweek, Zimmerman said that a strong motivation for the study was the lack of scientific evidence to support the massive advertisement campaign made for baby-train materials.

“Parents are getting a very mixed message here—they’re hearing loud and clear from marketers of these products that they can be very educational for their children. But in fact, there’s no scientific evidence to support that at all.”

“Baby videos claim to be educational but they don’t go through that process- they don’t develop learning objectives and they don’t go through rigorous testing.”

Last spring, Christakis and Zimmerman found that by three months, 40% of babies are regular viewers of DVDs, videos or television; by the time they are two years old, almost 90% are spending two to three hours each day in front of a screen.

Neuroscientists recommend human contact instead of TV shows for kids who are in the process of developing language skills, because real-life imitation plays an important part in the learning curve.

At 18 months, kids have a vocabulary of approximately 5-20 words, made up chiefly of nouns, and are able to follow simple commands. Their “jargon” is loaded with a lot of emotional content and they also tend to repeat a word indefinitely (a phenomenon called echolalia).

Dr. Vic Strasburger, pediatrics professor at the University Of New Mexico School Of Medicine, said that "Babies require face-to-face interaction to learn. They don't get that interaction from watching TV or videos. In fact, the watching probably interferes with the crucial wiring being laid down in their brains during early development."

Researchers say parents would be better off spending more time talking, singing, reading and playing with their babies and toddlers. Actually, regular story-reading was found to have a positive effect on the speed with which toddlers learn new words.

The American Academy of Pediatrics already recommends children under the age of 2 should not watch any television.

"I believe the onus is on the manufacturers to prove their claims that watching these programs can positively impact children's cognitive development," said Dimitri Christakis.

He was supported by Andrew Meltzoff, co-director of the University of Washington's Institute for Learning and Brain Sciences, who declared that parents’ care cannot be replaced by machines.

"They [parents] instinctively adjust their speech, eye gaze and social signals to support language acquisition," said Meltzoff.

"Watching attention-getting DVDs and TV may not be an even swap for warm social human interaction at this very young age. Old kids may be different, but the youngest babies seem to learn language best from people."