How much influence does the media have on the public?

[Phillip S.]

People would say that media has no serious influence on the public; then why do companies and politicians spend so much money in advertisements. Please, it's not just because they have money to blow away. If a movie shows high school football players laying in the middle of the street while cars closely drive by them, would real people that stupid to do the same thing? Probably not. Does the media reinforce or even create stereotypes that positively or negatively influence people's perception of other people? How many movies have you seen from the 70's, to the present where an Asians knows Kung Fu? That was just an example, actually I don't know any Asians who go around practicing Karate; they're just normal people. Another question is how is social networking changing the media's influence, if it has any, on the public?