Deindividuation Theory of Aggression

• http://www.ted.com/talks/lang/eng/philip_zimbardo_on_the_psychology_of_evil.html

• Deindividuation – to lose one’s sense of individuality and identity.

• Can occur in 2 main ways – – Becoming part of a crowd– Identifying with a particular role ( often

aided by wearing uniform or mask)

Can be used to explain aggression which occurs when in a group.

• Le Bon (1895) – individuals are more likely to behave in aggressive manner when part of a large anonymous group.

• A collective mindset is created and the group can become a ‘mob’.

Individuals feel less identifiable in a group, so the normal constraints that prevent aggressive behaviour may be lost. The shared responsibility for action reduces individual guilt.

Diener (1980)

• Deindividuation occurs when self awareness is blocked by environmental events.

• Critical factors include :– Strong feelings of

group membership– Increased levels of

arousal– Focus on external

events– Feeling of anonymity

The deindividuated individual is trapped in the moment, perception of time is distorted and they are unable to consider consequences.

Diener cont.

Prentice-Dunn & Rogers (1982)

• Modified Diener’s theory to distinguish between:– Public self awareness - concern over the impression of

yourself you are presenting to others when you are aware of being judged.

– Private self awareness – your sense of self, consisting of thoughts, feelings, values and internal standards of behaviour.

Reduction in either can result in aggressive behaviour, but only reductions in private self awareness can lead to genuine deindividuation.

Evaluation

• Zimbardo (1973) Stanford Prison experiment

You have 30 minutes to research and outline this classic experiment and apply deindividuation theory to the

guards aggressive behaviour.

Zimbardo (1969)

• Explored deindividuation in female undergraduates.• Group 1 dressed in white lab coats with hoods over their

faces• Group 2 wore large name tags.• All pps observed a woman being interviewed and evaluated

her performance by administering electric shocks.• Condition 1 – pleasant interviewee, condition 2 – obnoxious• Group 2 shocked the obnoxious interviewee more than the

pleasant one• Group 1 (deindividuated) shocked both interviewees

equally.• Zimbardo concluded that deindividuation increased

aggression, making it indiscriminate and not at all influenced by individual characteristics.

Is it relevant that all the participants

were women?

Ellison et al (1995)

• Field experiment – drivers of convertibles with tops up beeped more than those with tops down.

• Driving simulation exp’t with 289 psych student pps.

• Measured aggressive driving (speed, jumping red lights, collisions etc.) in tops up / tops down conditions.

• More aggression shown in tops up(anonymous) condition.

Is this experiment high or low in

ecological validity? Why?

Rehm et al (1987)

• Aggression in handball• Deindividuation was created by giving one team orange shirts, whilst

other team wore own clothes.• In boy teams, uniformed teams were

more aggressive than non-uniform.• In girl teams, no differences found.• Researchers concluded that uniform >

loss of individuality > deindividuation.Is there an alternative explanation? How can the

gender difference be explained?

Cross cultural evidence

• Watson (1973) – 24 cultures. • Warriors in face and body paint

more likely to kill, mutilate and torture captured prisoners.

• Silke (2003) – violent assaults in Northern Ireland.• 206 / 500 cases carried out by offenders wearing masks or disguises.•Anonymous attackers were more prolific and inflicted more serious physical injuries than identifiable attackers.