An art history professor from North Carolina has developed a unique method for drawing portraits of U.S. presidents and first ladies.

"It's known that kids that use more screen time tend to grow up in families that use more screen time," Hutton said. "Kids who report five hours of screen time could have parents who use 10 hours of screen time. White matter is made up of fibers, typically distributed into bundles called tracts, which form connections between brain cells and the rest of the nervous system. "It's not that the screen time damaged the white matter," he said, adding that what could be occurring is that screen time is too passive for brain development. Basic guidelines are as follows:Infants:No baby under 18 months old should be exposed to screen media, other than video chatting with friends and family, the AAP says.