Research for effects theories.

Here is a summing up of some effects theories courtesy of Wikipedia:

The Hypodermic Needle Model
The intended message is directly received and wholly accepted by the receiver.

Two-Step flow
The people with most access to media, and highest media literacy explain and diffuse the content to others. This is a modern version of the hypodermic needle model.

Uses and Gratifications
People are not helpless victims of mass media, but use the media to get specific gratifications.

Reception Theory
The meaning of a "text" is not inherent within the text itself, but the audience must elicit meaning based on their individual cultural background and life experiences

Obstinate Audience Theory
This theory assumes that there is a transactional communication between the audience and the media. The audience actively selects what messages to pay attention to. The Zimmerman-Bauer study found that the audience also participates in the communication by influencing the message.