Late last year, the American Academy of Pediatrics released their first guideline in 10 years on child-rearing, stating that it was inadvisable to let children under the age of two watch television. Now Dr. Dimitri Christakis, director of the Center for Childhood Health, Behavior, and Development at the Seattle Children's Research Institute, and professor of Pediatrics at the University of Washington, explains why.

His research, which will be published this week in Scientific Reports, was inspired by research published that, through observational studies, had concluded that television-watching early in life led to attention problems later in life. However, it is difficult to determine causality from observational studies. Moreover, it is unethical to test babies to see if they can cause behavioral problems, so Christakis and his team decided to recreate the effect for mice.

Christakis's mice were divided into two groups, one in a normal environment and one in which the mice were overstimulated. After the first 10 days of the mice's lives, the overstimulated mice's cartons were bombarded with audio from cartoons and flashing lights that were in rhythm with the audio for six hours a night. Their mothers also remained in the cartons with them. Then they tested cognition, behavior, and activity in the mice. They found that the overstimulated mice were hyperactive, took more risks, and had learning problems.

"Overstimulation during infancy can lead to brain problems," Dr. Christakis said. "The newborn brain grows three times in size during the first two years. We know that the mind is fine-tuned to the world babies live in."

In the past 30 years, the age at which babies have started regularly watching television has decreased from four years to four months. "Minds have evolved over millennia to process things in real time," says Dr. Christakis, "The TV, on the hand, moves at a surreal pace. The programs are very, very quick. Babies think that's how fast the real world happens, and they find it to be under-stimulating."

Dr. Christakis did not believe that the difference came about as a result of stress. They programmed the audio at "well below what is stressful for rodents. It was high enough to hear, but not high enough to cause stress." He also did not feel that the mothers were stressed as a result of the overstimulation.

For the optimal environment for babies, Dr. Christakis said, "Nothing is better than human interactions. Babies' activities should be structured around physical interactions, like the engagement with blocks, reading, and singing. The technologization of childhood is a new phenomenon."

Dr. Christakis said that he was not anti-television by any means. In fact, he mentioned research that indicated that appropriate television content could improve children's behavior after the age of two. But he said, "The newborn brain is different than older brains. Babies don't process content. It's just a bombardment of images and sounds."

More of Dr. Christakis's information on the impact of media and children can be found from his TED Talk below.