Do we have a herd mentality? Can politicians and ad men exploit us and predict patterns in society for control and financial gain?
The answer is most probably yes!
Beyond whatever research you're talking about, which it'd be great if you could include a link to,
This one is a diamond: http://en.wikipedia.org/wiki/Stanford_prison_experiment
Although not directly related to the pressures of a crowd so much as authority figures, this is the ultimate classic:http://en.wikipedia.org/wiki/Milgram_experiment
As much as we all have this optimism bias that we would be the exception, the studies show we're all pretty much broken down eventually under a certain amount of pressure. :/
This is why we must accumulate good karma to have the relative circumstances to realize. If you put me in prison today, I'd stop being even a mediocre aspirant Bodhisattva in about three hours.