Festinger et al (1952) stated that deindividuation is when a person looses their sense of self-awareness and individuality.
People are usually inhibited from acting aggressively by the threat of punishment - but this is taken away if they feel they cannot be identified.
Large groups of people can remain anonymous, encouraging the display of aggressive behaviour.
When someone is aware that they are being watched they monitor their behaviour for fear of being judged and act by a moral code that they learnt throughout their lives.
Zimbardo (1969) - using female participants investigated the role of deindividuation on delivery of punishment. (a variation of Milgram's electric shock exp)
- One group wore lab coats with hoods - were not identifiable