It turns out TV -- well, some TV -- can be good for your mind.

For decades, we've worked under the assumption that mass culture follows a path declining steadily toward lowest-common-denominator standards, presumably because the ''masses'' want dumb, simple pleasures and big media companies try to give the masses what they want. But as that ''24'' episode suggests, the exact opposite is happening: the culture is getting more cognitively demanding, not less. To make sense of an episode of ''24,'' you have to integrate far more information than you would have a few decades ago watching a comparable show. Beneath the violence and the ethnic stereotypes, another trend appears: to keep up with entertainment like ''24,'' you have to pay attention, make inferences, track shifting social relationships.