" TV also poisons attention spans and the ability to focus, a classic hallmark of executive function. For each additional hour of TV watched by a child under the age of 3, the likelihood of an attentional problem by age 7 increased by about 10 percent. So a preschooler who watches three hours of TV per day is 30 percent more likely to have attentional problems than a child who watches no TV. "

― John Medina , Brain Rules for Baby: How to Raise a Smart and Happy Child from Zero to Five