Effect of Graffitti

Each time I go out and pass by the streets and shops of Cairo, especially lately ive gotten intruiged by the graffiti on almost every plain surface available.
On billboards, on buses, on walls, even on the metro it self.
messages messages messages.
Everywhere you go you pass by those written messages..sometimes theyre artistic depictions as well. It makes me wonder...what is the effect on a commuter that passes graffiti messages everyday?
I commute to college twice a day for around 2 hours in total, five (sometimes 6) days a week. For months and months.
How will passing by those messages, consciously (then as u get accustomed to them, subconsciously) affect us and our opinions?
Most if not all of those messages are political..and I can understand that they have a direct and understandable political influence on people (i will demonstrate my point). What intruiges me more is what non-political, subliminal effect do these messages have on our emotional health? our moral system? how we behave as people in society? how we communicate?
To what degree is a (for example) "Freedom for Syria" message inscribed on a wall or a flag painted on the back of a bus affect us? Or a "so and so is a murderer" or a "so and so is my president"
I say "so and so" because I dont want to limit this topic to current political events in the middle east. Rather, by eliminating names our Russian baldy friends could also relate :D *note: this is an inside joke, youre unlikely to understand if youre actually from russia and are baldy..vlad..*cough*
So back to graffitti, I opened up this discussion at the table during dinner and the conclusions were interesting, at least to me.
Directly if I support A and I see graffitti in support of A my beliefs will be strengthened and reinforced. If the graffitti of A are wide spread and constant to many places, it gives the supporter of A a sense of comfort and further affirmation that not only is his/her support correct but that many many other ppl over a large geographical area believe in the same idea.
Even if this isnt the case in reality.
Man feels strength when he realizes that many other men believe in what he believes in.
Even if a million individuals feel the need for revolution and are convinced with it..nothing will happen if they arent aware that people believe in what they believe in.
That is the psychology of censoring and the social networking restriction in countries like china. If people were allowed to openly share their ideolgies and realize that others have similar views, too soon people will conglomerate and create revolutions everyday.
So graffitti has a reinforcing ability on the supporters of a certain side. It is saying "yes! youre right..we think like u! join in"
I would think that graffitti to a certain degree can lower the threshold for taking action. I cannot say it is an actual ingredient but it maybe a small enzyme in the complex cauldron of human motivations and external influences.
However the tendency for the graffitti effect to wane is understood, simply due to accustoming to the message. Graffitti is a force yet it is also evanescent.
How about the graffitti that supports A and an observer who supports B or doesnt support A?
Would these messages have an effect?
Surely they do. Probably in the opposite direction. I say probably since all our reactions are varied but from what we concluded, I predict that a supporter of B will become more opposing of A.
But..their support for B is unlikely to be strengthened.
A weak supporter of B may become a weaker still supporter of B by seeing supporter of A messages that are loud, clear, well distributed and strong. However I doubt of one's entire belief system could be changed by graffitti no matter how strong the message.
All these conclusions are merely hypotheses, I admit I have not read any literature on such a topic (eventhough I'm certain that the influence of graffitti has been scientifically tested and still quite uncertain).
I'm going to read up literature on this and see where it takes me.
Also I havent reached an answer to the other part of my question which is the indirect subliminal effect graffitti might have on our daily lives.
A study carried out in Germany concluded that people living in areas that are unclean with alot of rubbish (and graffitti) are areas which predispose the residents to harbour more racial prejudice and hold on to false stereotypes.
Too bad however that a few weeks later the author was reported and put on the black list for fraud and fabrication of results of the study.
I'll be back :D