There's no doubt about it. Since television was invented, the standardized tests scores have had diminishing returns. Educators have been desperately trying to remedy this by addressing such things as individual learning styles, motivation, relevance of course material,and family values, to name a few.
Granted, some progress has been made here, but not everyone is reaping great benefits.
Is television indirectly responsible for this phenomenon, or is the correlation just a coincidence, and there are other influences at work ?

Yes, it's a descending spiral.  The more TV you watch, the dumber you get.  The dumber you get, the dumber TV shows have to get to pander to the lowest common denominator.

I remember hearing years ago about TV shows being produced for a viewer with an average mental age of about 12.  Gotta be down to 9 by now.

I don't think so. I believe it is caused by greater availibity. For instance, computers are the latest thing to come down in price so that everyone can have one. Originally they were 2-8 thousand dollars for one. So anyone that bought one either had a lot of spare income, or needed it, and learned how to use it.
Today you can get one for around 300 bucks new, or 100 dollars used. So now it is an everyone has one, I should get one type thing. How many people do you know that own a computer, but are computer illiterate? A lot I bet. Couldn't install a program to save their lives, and can barely do e-mail or IM's. Yet here they have a computer. Is it because microsoft made it easier for everyone to use a computer, so people are dumber, thus the viscious circle, the programs have to be dumber so people can use them? No. It is because dumber people now have access where as they would not before, so they are now the market that drives sales, so products must match.

I think tv has something to do with lower test scores, but I don't think tv is the only factor that effects the scores.

I think society has become dumber and it seems like now it is "cool" to be dumber in some situations. What I mean is it seems like it is socially accepted to not be as smart as others.

Thanks shaggy.

Depends on what you're watching.  There's a lot of good educational TV, especially if you have cable or satellite.

PGM - I know you were just distracted by CNN, but you meant "accepted", right?