Two Step Theory

Lazarsfeld and Katz created the Two Step Theory in 1944. The two step theory is based on having a middleman between the mass media and the mass audience. The middle man or the Opinion Leaders dissect the news from the media and present it to the mass audience in a way that is humorous or easier to understand.

Cultivation Theory

George Gerbner (1980) came up with a theory based on the massive influence of television on the public. He argued that it was gradual long term effects rather that immediate effects (like in the hypodermic needle theory). He also argued that television reinforced ideas rather than changed peoples perceptions. For example, people who have bad perceptions of immigrants are likely to read the Daily Mail as they back up this with negative headlines. 

Hypodermic Needle

This theory was thought up in the 1920s to 30s in Frankfurt, Germany.  It was in response to Propaganda posters which were influencing the public.  The theory said that the media is powerful and controlling and the audience is basically passive and allows ideas and beliefs to be injected into them.  Nowadays this is most relevant to advertising - eg. Red Bull with its sponsorship of extreme sports leading people to think that it is an aspirational brand.  Also the Levis Launderette advert in the 1980s with Nick Kamen which sold millions of jeans. This theory can be applied to music videos as was can sell as style through it.