Toddlers exposed to DVDs and videos marketed as "educational" showed no greater improvement in their vocabularies than children not exposed to such programming, a study said Wednesday.
In fact, researchers from the University of Virginia and Vanderbilt University said their findings suggest babies learn best in everyday activities, without any exposure to videos.
The study, published in the journal Psychological Science, tested 72 infants between the ages of 12 and 18 months.
The infants were divided into four groups of 18, some of whom were shown a 39-minute video with images of common household objects a speaker identified by name.
Toddlers from the first group watched the video in the presence of a parent. Children from the second group watched the DVD without an adult.
In the third group, parents were told to teach their children as many words as they could from a list of 25 also featured on the DVD, without allowing them to watch it.
In the fourth group, no videos were screened and parents did not make any extraordinary effort to teach their children vocabulary words.
Instead, this "control group" provided a baseline of normal vocabulary growth against which the other three groups were measured.
After one month, all of the children were tested on their knowledge of a list of words that appeared in the DVD.
The researchers found that the infants who regularly watched the DVD during the period learned "very little" from their exposure to it, regardless of whether a parent accompanied them. Indeed, they learned no more words featured on the DVD than children who had never seen it.
The study also found that parents who enjoyed the DVD thought their child had learned more from it than parents who were unimpressed by it -- even though "there was no difference in how many words were learned by the children of these two groups of parents," according to researchers.
"If you want to show your infant 'baby videos,' that's fine. Just don't expect the child to learn a great deal from it," said lead author Judy DeLoache of the University of Virginia.
A set of "Baby Einstein" DVDs, one of the most popular brands of educational videos geared toward infants, costs around 46 dollars in the United States. A single DVD can cost about 20 dollars.
But DeLoache said that her study showed the investment probably won't pay off.
What parents interpret as knowledge acquired by watching the DVDs is actually just normal developmental change, she said.
"Your children are going to learn language anyway," said DeLoache, adding that the best way to help young children learn new words is to simply talk to them.
Explore further: What makes a good horror movie?