The Frankfurt School Theory

The Frankfurt School were a group of Jewish theorists that lived in Germany. They developed concerns about the power of modern mass media in the early to mid 1920s. The founders of this were left wing (neo marxist) and under threat in the context of pre war Nazi Germany. They moved to America and refined their model in an era if expanding media in post war America.
The Effects Theory
The original model for the audience was the effect model also known as the hypodemic needle, which stressed the effects of the mass media on their audiences. This basically means that the audience are metophorically injected with an ideology through media into their heads. The model owes much to the supposed power of the mass media in particular film.
We can be affected by what we see on the TV, internet, video games etc. People worry about the hypodemic needle is true. Their concerns were for those vulnerable members of the population who could be corrupted as a result of such material. For example the murder of Jamie Bulger- the two children that killed watched Chucky then killed him.
To some extent this theory is right because we do copy somethings we see in the media without realising. For example the word "Minger" without Ali G we wouldn't use it. And "Eat my shorts" by Bart Simpson from The Simpsons.