SAN FRANCISCO — Children younger than 8 are spending twice as much time on screen media as they do reading or being read to, according to a new national study. And as many as 40 percent of toddlers ages 2 to 4 and more than half of those 5 to 8 use smartphones, video iPods, iPads and similar devices.

That’s according to “Zero to Eight,” a national study by Common Sense Media, which this week is launching a national research center to track children’s screen time. Read more…