There are many studies of political movements and the related individual and interpersonal psychology of such. Early theories focused on the quest for power and control.
Later theories focused on subsets of the generally satisfied populace which set out to contribute to specific causes or to right specific wrongs. This is an area that is ripe for study of the individual and group psycholigical processes and psychosocial dynamics.
Classic theories focused on labor and the rights of the workers in relation to the corporate/ruling classes. Democracies are born in eras of oppression of the majority. The individual, at some point goes through a psychological process of joining, abstaining or opposing. Study of the process from the beginning would reap great rewards in understanding the flow from dissatisfied individual to activist.
Revolutions are born in the egregious misuse and oppression of the masses. Guerrila warfare is born in the subgroup which cannot obtain the support of the majority, or when the ruling and corporate classes have totalitarian control. Religious movements are born in the desire of one religion to dominate over all others, or, conversely, to have the right to exist. The mass and individual psychology of the participants and opposition is an area of great interest to those who organize as well as those who oppose.
From the Protestant Reformation to the current "green movements" and "tea party" political movements, there is something that presents a conflict between individual perceptions of where government, religion or society should be, and where it actually is. Then there are those who believe that the movement, itself, represents directions that are completely undesireable, creating conflict at the individual, group and national levels.
At the individual level,the conflict is profound. The government which taxes and enforces laws, but which does not protect the individual from corporate excesses, or which squanders the public treasury and redistributes it under corrupted practices,is on the individual's mind. When a charismatic leader or an organization promises to amplify the individual's power and voice, there are greater odds of joining and even being motivated to participate.
At the group level, those with like minds on a variety of interests can be convinced to consolidate their power through various control and manipulation mechanisms. Those mechanisims are important for study.
When the psychology becomes deviant or dysfunctional, the small grassroots group can become a large force that can disrupt,protest, and carry out actions on a larger scale. This is the time of the charismatic leader who can aggregate and motivate large groups of people to actions and levels of aggression or hysteria that they would normally not do.
In the psychology of political movements, the psychology of the charismatic leader or "rabble rouser" is highly critical. The problem is that "charisma", like "leadership", is a difficult entity to pin down in terms of definition or standard features that apply to all charismatic entities.
Today, some of the most physically unattractive, mentally unstable, untruthful, personally unethical, and otherwise unlikely candidates have enormous sway over millions through the media.
Studying how they aggregate such attention and power is important. One astounding ability is of the followers of a charismatic leader to completely deny the facts about the leader's violation of their own group standards. Currently, lies, personal misconduct, proffessional misconduct and other problems that are in opposition to the public utterances of charismatic leaders are overlooked as if they did not exist. One talk radio host called for the unrelenting and indiscriminate arrest of drug addicts...while he was engaging in illegal substance abuse, himself. His listening public continue to demonstrate an astounding denial of fact in his case, while calling for the demise of those who disagree with their social and political platforms.
The psychology of such mass denial is a critical area of study.
Also, the psychology that is used by the corporate and lobbying interests today is of particular note. The organizers behind the recent "town hall disruptions" in America can be easily traced to organizations that have ties to corporate lobbying firms which provide instructions as to how to behave, and even what to say. The effect is to provide groups of individuals who intimidate and disrupt events. As to whether these individuals actually believe in any cause or movement, the facts become unclear as soon as the corporation or lobbying firm is identified, while the participants fade back into invisibility. Meanwhile, average citizens become intimidated and fearful.
There are individual and group psychological issues that call for study and investigation. The abnormal psychology of extremist activists is also of interest in political movements. Extremist activism is a form of "guerrilla" movement that comes when the mainstream will not support the cause or provide law, law enforcement or even practical support for such activities as completely ending animal testing, abortion clinics, Japanese whaling for profit, aggregated or individual tax problems and so on.
In some extremist movements, a return to White Supremacy, extreme anti immigrant policies, humans having no impact on the environment, and other generally unacceptable and untenable absolute demands are made. This needs to be examined, as such movements can do great damage.
In one sense, the nature of abuse that is carried out by some regional and national political movements can be studied in relation to theories and principles of verbal, physical and emotional abuse and control, but on a much larger scale.
Other group and organized abuse comes from individuals who organize into "hate groups" who have a variety of targets. There are Black, White, Asian and other hate groups who have been the subject of many psychological studies, but such groups can be tight knit, and do not allow any study to be done, except by undercover law enforcement professionals.
In summary, the psychology of political movements is a field that is here to stay and which has much more work to do. The results would be helpful in profiling and handling deviant and destructive national movements, or even in identifying and responding to the most pressing needs of the population.