Louis Althusser was a French Marxist sociologist who explored the concept of ideology. Ideology refers to the theory that social institutions (such as religion, the education system, and of course - the media) take control of people's thoughts and beliefs, thus overriding their individuality.
As the media is generally controlled by the bourgeoisie, it transmits 'ideals' which conveniently reinforce the class inequalities seen throughout society. This can be seen from media bias which can act as propaganda (Chomsky, 1992) and through class representation (below).
One of the most obvious examples of how the media can transmit 'ideals' is through the way the media represents different groups of people [LINK]. Mentioning the ideology theory and Barthe's mythologies theory will inevitably end up in a "chicken or the egg" argument - whilst Barthe says that the stereotype based representations are given to satisfy the audience's expectations, Althusser's ideology argument would suggest that those expectations only exist because the media has presented them to the audience previously.
The Marxist belief that the ruling class have control over the proletariat is heavily supported by this idea of ideology; the media presents the audience with plenty of justification as to why they should live their lives in a certain way. For example, if we go with the way that pretty much every programme ever made in the history of television has at some point had a romance based storyline, we can see that the media promotes having a partner to settle down as being an 'ideal' lifestyle. In actuality, this could be seen as taking advantage of how people are more inclined to aim for a good job if they have a partner (and eventually children) to look after, thus motivating the workforce.
Audiences & Institutions
I did previously touch on this in the previous post but it is somewhat relevant to mention again the way in which institutions make use of ideology to sell their products.
Institutions who have a product to sell need to convince the potential audience that it is worth buying - this is done through marketing. Successful marketing revolves around ensuring that as many people as possible buy the product; thus it is important to ensure that the marketing appeals to the masses.
This can be done by first spreading 'ideal' beliefs, then ensuring the product being sold meets the ideals. This is an example of institutional power; once they have created a desired ideal, they are free to market as many products as they feel the need towards this ideal, hence why sequels and spin-offs are usually commercially successful.
Post-modern/social action (interactionalist) theorists oppose the idea of ideology brainwashing the population on the basis that they feel that society is instead run on the actions of individuals; and that although the media as an institution may have the potential to promote certain beliefs, it is ultimately up to the individual as to whether they take on those communicated or not.