I agree that, in general, children watch way too much television and that the programs foster short attention spans. That's one of the reasons I don't allow my children to watch Sesame Street, with all of its short, constantly changing subject matter.
Given that, my oldest son has difficulty concentrating. He watches precious little TV -- less than 30 minutes on the average day. Regularly, he doesn't watch TV for several days at a time. Both he and his brother haven't seen any in the past two weeks.
Also, we homeschool, so he doesn't have to sit still as in a traditional school setting. Still, he had difficulting concentrating, even in a quiet room.
Do I think ADD/ADHD is over diagnosed? Yes. Still there are children like my son who don't eat lots of sugar or caffein, who don't watch lots of TV, who get lots of exercise, who are spanked when they need it, who have two loving parents living in the same hhome, one of whom stays at home fulltime, who still exhibit the symptoms of ADD/ADHD.
Believe it or not, We didn't have a television in our house until a year ago, then I subscribed to Sattelite TV, Sky Angel...For 12 years, there wasn't a television, I didn't miss a thing. I had teachers threaten me with child abuse because I was keeping something from my kids...
I think this formation at an early age is the missing element in the debate.
No, they watch television because they have short attention spans AND because all entertainment allows passivity, and these are two distinct and separate issues.