Parents should limit children under the age of two from watching TV, say pediatricians who also advise against having it on in the background.

The American Academy of Pediatrics reaffirmed its policy of discouraging screen time for babies and toddlers on Tuesday at its national conference in Boston. 

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A developmental divide means that children between the ages of 1½ and 2½ don't connect with the characters on TV. (Bazuki Muhammad/Reuters)

Yet in a recent survey, 90 per cent of parents said their children under age two watch some form of electronic media, the group said.

More is now known about the potential negative effects of media exposure on early brain development, and the best ways to help children learn, according to the new policy statement.

"Young children learn best from — and need — interaction with humans, not screens," the statement said.

The group also added a section on "background" TV, saying that if a TV is on, studies show a child moves their eyes up to the screen every 20 seconds. That can cause them to lose focus or switch to another task more easily without completing the first, said Dr. Ari Brown, a pediatrician and lead author of the paper.

Even if young children watch high-quality programs, a developmental divide means that children between the ages of 1½ and 2½ don't connect with the characters.

When the TV is on, real-life talking goes down and children under two who watch TV a lot often have delayed language abilities, researchers found.

"Unstructured playtime is more valuable for the developing brain than any electronic media exposure. If a parent is not able to actively play with a child, that child should have solo playtime with an adult nearby," the statement recommends.

Playing independently, such as with nesting cups, allows young children to learn creativity, problem solving and exercise their imagination, the group said.

If parents choose to engage young children with electronic media, the group suggested having concrete strategies to manage it, and ideally watch programs with the child.

The recommendation for children under two to get zero screen time applies to passive TV. There isn’t enough research yet on interactive screens such as computers and tablets.