Zimbardo, Phillip G. The Human Choice: Individuation, Reason, and Order Versus Deindividuation, Impulse, and Chaos, In W. T. Arnold and D. Levine (eds.), Nebraska symposium on Motiviation, Vol 17., 1969.

"When a man exercises his volition, chooses to commit himself to a course of action, and accepts personal responsitiliy for its consequences, he distinguishes himself as unique among living creatures and calls into question our laws of behavioral control"

"In the process of having to generate intrinsic justifications in order to make a discrepant commitment appear rational and consistent, man shifts the locus of contorl of his behavior from external stimul to internal cognitive controls."

Consistency, Rationality and responsibility are prized in society. "The act of freely making a commitment for which one assumes responsibility individuates the decision maker".

But the world seems to be acting otherwise. People are excercising control to destroy themselves and others.

Festinger showed in the 1950's that there is a "reduction in inner restraints" toward expression of counter-norm behavior when individuals are 'submerged in a group".

Ziller proposed that "individuation is desireable withing a supportable social climate, but deindividuation is sought as a defense against a threatening environment." Deinviduation results in a lowering of the threshold for expressing inhibited behaviors.

If one has been inhibiting a certain pleasurable behavior because of social norms, a lowering ot that inhibition could trigger the start of the behavior which would continue until some other outside force acted on it.

Traditionally, festivals and parties have served for people to "blow off" destructive tendencies by lowering inhibition a bit. Future thinking and responsibility reduce urges for immediate gratification. History and logic force us to perceive continuity and rational consistency, legal systems impose responsibility and liability.

Anonymity (lack of criticism by others) should reduce inhibitions of behavior. The inhibiting effects of responsibility can be reduced if the behavior is done by a group or if another accepts responsibility.

Preparatory arousal can also reduce inhibitions and propel a group toward action. War dances are an example.

Often to eliminate inhibition the subject has to experience intense sensory overload or become absorbed in the action itself, almost a non-cognitive feedback system. Novel or unstructured situations also can reduce constraints. Drugs can alter conscious states.

Deindivituated behavior is emotional, impulsive, irrational, regressive, and atypical for the person. The normal feedback loops that would inhibit such behavior normally are not working. Deindividuation is unresponsive to many features of the situation including the victim or states of self that would resist such action.

Maybe deindividuated action can be stopped up to a point through rational arguments and interventions, but past a point of no return mob behavior rules.

Investigations
They set up group anonymity among college coeds and had the group deliver electric shocks to another girl.. The anonymous girls exhibited much more agression to shock than the groups where everyone wore name tags. In the anonymous groups their agression increased with successive trials too. While there was no "enforcer" like in Milgram's studies, the girls obediently shocked the victim for as long as allowed.

"Conditions which induce feelings of remoteness lead to lowered self-consciousness, less embarassment, and reduced inhibitions about punishing the victim."

Another study allowed a release of agression by the subjects against some confederates pretending to be resisters. The "catharsis" had no effect on reducing agression and actually increased it a bit.

The test was duplicated among a group of Belgian soldiers under even stricter control of the important variables. However, the opposite effect was found -- the anonymous group shocked the victim less often and will less intensity, and felt less satisfied after shocking them. In this case the soldiers were somewhat deinviduated by their roles as soldiers. Putting hoods over their faces made them feel isolated and more anxious. The soldiers in groups identified actually felt more deindividuated because of the solider's group mentality.

The researchers then repeated the New York coed experiment, but only hooded one person in the group who then "stood out". These alone non-identified subjects then became less agressive than the previous group of all hooded, anonymous subjects.

Deindivituated behaviors are more likely when loss of personal identity occurs in a group setting than alone (when there is no group support).

The researchers also conducted a field experiment in auto vandalism. A car left on a street in New York was stripped in 10 minutes. Over 26 more hours a steady parade of vandals removed all sorts of parts. Nine hours later destruction began. In less than three days 23 incidents of destructive behavior. In fact, most vandalism was observed by one ore more passerbys, most desturction was during the day. In Palo Alto, the car was untouched and even the hood was lowered by a passerby so it wouldn't get wet in the rain!. However, once the researchers initiated some vandalism to the car at Stanford, others eventually joined in.

Dehumanization is possible when a large flow of people must be processed. Also people become desensitized to the empathies aroused by unfortunate people and eventually felt helpless and then resentful at the emotional burden caused by these unfortunates. Doctors must learn to see patients as bodies to distance themselves from the immoral act of cutting into another person. Others who are doing something purely for self-gratification need to dehumanize others.