David Suzuki tells of making television science programs. He thought people would turn on TV to watch his program, then turn it off and discuss.

Of course people don’t watch television that way at all. They come home, they turn it on, and it’s there. And they tune in and out, assaulted by a barrage of images. By the time they go to bed at night, their brains are mush. They retain bits and pieces with no idea where it came from.

(From the highlights of Social Change Conference, 1995).

When confronted with the negative effects of television, people often claim “I only watch the Discovery / History / Nature channel”. Your brain still turns to mush. Put the TV in a cupboard.