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  • It is behaviour aimed at harming others. Antisocial behaviour; generally considered to be behaviour that harms, or intends to harm someone, or something. Intentional and destructive.

There are three explanations for aggression:

  • Biological
  • Psychodynamic
  • Social Learning

Biological approach includes:

  • Hormones
  • Chromosomal abnormality
  • Brain biology and brain disease
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Biological approach

Chromosomal abnormality:

  • There is a higher than normal proportion of men with an extra Y chromosome amongst violent offenders. When the 23rd chromosome (sex chromosome) fails to divide, some men end up with an XYY arrangment instead of the normal XY
  • This has certain affects including making men more aggressive than normal


  • Widely accepted that males are more aggressive than females
  • Therefore can be linked to hormones:
    • Testosterone is considered to be a mainly male hormone
    • Therefore this could be a cause of aggression in males
  • Supported by reports of higher levels of testosterone in violent criminals than in non-violent criminals
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Biological approach

Brain Biology:

  • Explanation is that it's caused by an interaction of different parts of the brain
  • Aggression, like other instinctive behaviour, seems to be associated with the limbic system. This is the part of the brain that influences things like eating, sexual behaviour and aggression.
  • The part of the brain that controls these behaviours and stops us from being aggressive is the prefrontal cortex. This is highly involved in learning. It knows when instinctive behaviour is appropriate and when it is not.
  • Brain disease affecting either the limbic system of the prefrontal cortex may lead to abnormally high levels of aggression.
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Young et al (1959)

Aim: To see what effect hormones have on aggressive behaviour

Method: Young injected pregnant rhesus monkeys with testosterone and observed the levels of aggression in their offspring as they matured.

Results: The high levels of testosterone during pregnancy made the females grow up to behave like male monkeys - they engaged in rough and tumble play and challenged the males for dominance in their troop.

Conclusion: Testosterone does seem to play a vital part in aggressive behaviour.

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Raine (1997)

Aim: To investigate the brains of murderers

Methods: Reseachers gave 41 murderers in California a PET scan and compared them with a similar group of non-murderers

Results: There were some differences, for example, activity in the prefrontal cortex of the murderers was lower than in non-murderers

Conclusion: When the prefrontal cortex (and other parts of the brain) is not working normally, it can lead to people committing violent crimes.

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Psychodynamic Approach

  • The main focus of this approach is that aggression is innate (inborn)
  • Freud believed that we are all driven by unconscious thoughts and feelings
  • He suggested that we had an unconscious instinct driving our aggression called Thanatos.
  • This is what drives us towards self destruction. This builds up inside us, creating a pressure until sooner or later we cannot control it and it makes us do something aggressive.
  • Freud believed that we used defence mechanisms to redirect our anger. These defence mechanisms were called displacement and sublimation.
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Barker (1941)

Aim: To see the effect of frustration on aggressive behaviour

Method: Children were kept waiting a long time before being allowed to play in a room full of attractive toys. Their behaviour was then observed.

Results: The children were more aggressive and destructive than other children who had not been frustrated by being kept waiting.

Conclusion: Being frustrated does lead to an increase in aggression.

Early research says that frustration does lead to aggression but was later changed to frustration may lead to aggression.

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Berkowitz (1968)

Aim: To investigate the idea that people could learn to associate a particular stimulus (such as a gun) with anger or ways of releasing anger.

Method: Berkowitz demonstrated this in a series of experiments in which participants were angered by someone who was a confederate of the experiment. Participants were then given the oppotunity to deliver mild shocks to the confederate. Some participants saw a shotgun and revolver next to the shock switches, and some of those participants were told they belonged to the person who had made them angry. Another group saw neutral objects such as a badminton racket and a control group saw no other objects.

Results: The results showed that more shocks were delivered by participants who saw the guns than those in the group that saw a badminton racket or no objects.

Conclusion: Berkowitz proposed that people learn to associate particular stimuli (such as a gun, a boxing match or a person) with anger or ways of releasing anger. When the individual is frustrated, this creates anger, and a gun, for example, becomes a cue for aggression.

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Berkowitz (1968) - continued


As it is a laboratory study, it means the variables are controlled but the tasks are artificial. Consequently, the study may lack ecological validity. During this study, the participants may have developed demand characteristics, meaning their behaviour may have been influenced. The study was conducted on only university students, so there is a target population which limits the ability to generalise the results to other groups of people.

Practical application:

  • We should be aware of what images we show on the television and the associations made between them - certification rating for films is a good idea
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Social Learning Theory

Vicarious experience is the situation in which a person will copy a behaviour that is seen to have been rewarded in the model.

Imitation is copying behaviour and is the fastest type of learning in both humans and animals. Behaviour may be imitated because it is seen as rewarding, but if positive reinforcement does not follow, imitation will cease.

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Bandura et al (1961)

Aim: to test the idea that children could learn to become aggressive through imitating another person behaving aggressively.

Method: In Bandura's basic procedure, children aged between 3 and 5 years old saw an adult behave aggressively towards a large inflatable doll (called a bobo doll)

Results: They had the chance to play with a range of toys, including a bobo doll, while observers watched their behaviour. One of the findings was that the children showed significantly more imittion of a same-sex model and boys performed more acts of aggression than girls.

Mean scores of imitative aggression of a male and female model:

Participants gender      Female model      Male model

Female                            19                       9

Male                                17                      38

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Bandura et al (1961) - continued

Conclusion: We can conclude that all the children had learned the behaviour but they were more likely to imitate same-sex or reinforced models

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Megargee and Mendelsohn (1962)

Aim: To see if there is a link between aggression and personality type

Method: People who had committed brutally aggressive crimes were interviewed and given personality tests

Results: These criminals seemed to have been 'over controlled' and repressed their anger until it built up to such an extent that it just exploded following something really trival

Conclusion: If people do not let thier aggressive instinct out in small amounts from time to time, the build-up will be so great that they will not be able to control it.

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Patterson et al (1967)

Aim: To investigate the effects of neegative reinforcement on aggressive behaviour

Method: Children were watched in an observational study. The researchers noted acts of interpersonal aggression and the immediate consequence of the actions. 

Results: Results showed that, for children showing the highest levels of aggression, the most common consequence was a rewarding one for the child

Children who were aggressive and were then punished (the victim fought back) were the least likely to be aggressive. However, Patterson found evidence of negative reinforcement in children who were not very aggressive. If they sometimes fought back when they were attacked, they gradually became more aggressive themselves.

Conclusion: Overall these results auggest that if sggressive behaviour is reinforced, it is more likely to repeated.

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Libert and Baron (1972)

Aim: To see if watching violent television programmes had any effect on aggressive behaviour in children

Method: One group of children were shown a quite violent television programme, while another were shown an equally exciting sporting event. The two groups were then observed at play.

Results: The group who had watched the violent programme were more aggressive than the group who had watched the sporting programme.

Conclusion: Watching violence on television increases the level of aggression in children's behaviour.

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Charlton et al (2000)

Aim: To see if the introduction of television (and therefore aggressive role models) to a community would affect the aggressive behaviour of children.

Method: For two years after the island of St. Helena first received television transmissions, the behaviour of the children was monitored.

Results: The children did not show an increae in aggressive behaviour after television was introduced compared to before it was introduced.

Connclusion: Merely watching aggressive role models will not be sufficient to make children copy aggressive behaviour.

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Reducing Aggression

Drug therapy:

  • The biological theory of aggression proposes that the prefrontal cortex does not process properly - so if this region can be stimulated then aggression should be reduced.
  • Ritalin is used to stimulate the brain and therefore the prefrontal cortex and has been used to reduce the aggression shown in children suffering with ADHD. If the prefrontal cortex is stimulated, it is able to control the aggressive instincts caused by the limbic system.


  • Surgery to remove or destroy the part of the brain that is not functioning properly. Usually the limbic system.
  • This may be done by inserting a probe to a very precise location and heating up the very end to kill the nerves.
  • Because research has shown the limbic system to be responsible for aggressive behaviour, it is usually part of the limbic system that is destroyed.

Evaluation: Drugs tend to have side effects which could impact on an individual. Surgery is permanent.

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Reducing Aggression


  • Freud would suggest it is a good idea to watch violent things on TV because it is carthartic - it gets it out of your system


  • Often hard to avoid frustrations
  • The theories conflict (e.g. pschodynamic theory says that the fans of a team that loses at football should be frustrated and therefore aggressive. However, biological suggests that the supporters of the team that wins will have an increase in testosterone and therefore become more aggressive.)
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Bandura (1963)

Aim: To see if observing a role model being punished would reduce the chance of aggression being copied

Method: children were shown an adult model either being punished or reinforced for acting aggressively.

Results: Those children who saw the model being punished were less aggressive themselves than those who saw the model reinforced.

Conclusion: If children see that aggression brings a punishment, they will not copy it.

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Huesmann et al (1983)

Aim: To see if teaching children to think more carefully about what they see would reduce aggression.

Method: A group of children were taught to realise that what happens on television is not real. The camera sometimes depicts things that do not happen, and people mostly use non-violent methods of resolving problems. The children's behaviour was then compared with that of another group of children who did not receive any training.

Results: The other children who received training showed less aggression than the other group.

Conclusion: Aggression will be reduced by making children think about how they behave so that role models on television becomes less influential.

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