Aggression - Biological

Question 1

What are the three main biological explanations?

Answer 1

• Genetics
• Neural Mechanisms
• Hormonal Mechanisms

Question 2

What is selective breeding?

Answer 2

The process of choosing animals with desired characteristics and repeating them over generations.

For example dogs.

Question 3

Which piece of research supports selective breeding and what did they do?

Answer 3

Hood and Cairns (1989)

• Bred mice with significantly high levels of aggression.
• Aggression was reduced when reared with siblings.
• Extent to which we can generalise to humans is limited .

Question 4

What is the MAOA gene?

Answer 4

• Controls the production of MAOA that is an enzyme involved in processing neurotransmitters such as serotonin.

Question 5

What did Brummer (1993) do and find regarding the MAOA gene?

Answer 5

• Studies an extended family in the Netherlands where several family members were highly aggressive e.g. violent crimes
• Identified a different gene and therefore low levels of MAOA are not the only cause.
• Cannot establish cause and effect

Question 6

State a supportive piece of research regarding the MAOA gene?

Answer 6

Cases et al (1995)

• Found they could disable the MAOA gene and lead to rats being aggressive.
• Now have cause and effect.

Question 7

What is the key study regarding genetics and what was found?

Answer 7

Christiansen (1977)

• Twin study : 3856 pairs in Denmark.
• MZ and DZ twins were compared for criminal activity.
• Male MZ twins showed 35% concordance rate compared to 12% in DZ twins.
• Female MZ showed 12% compared to 8% DZ.
• Suggests a genetic component to aggression, but there is not 100% concordance rate.

Question 8

Give three evaluative points regarding genetics and aggression?

Answer 8

• Inconclusive as no single gene is said to be the only cause.
• Reductionist as explains aggression through the biological explanation and ignores free will.
• Caspi et al (2002) suggest aggression is caused due to a faulty MAOA gene plus environmental stress factors.

Question 9

Explain what the Limbic System is?

Answer 9

One part of the Limbic System that has a strong connection with aggression would the amygdala.

The hypothalamus plays a regulatory role in aggression.

Question 10

Regarding the hypothalamus, give a piece of research appropriate?

Answer 10

Bard and Mountcastle (1937)

• Destruction of the hypothalamus caused rage in cats.

Question 11

What role does serotonin play in aggression?

Answer 11

Has been implicated in the control of aggressive behaviour.

Question 12

Give one piece of research regarding serotonin levels and the effect they have?

Answer 12

Valzelli and Bernasconi (1979)

• Found nice bred with low levels of serotonin are more aggressive than those with higher levels.

Question 13

What is Tryptophan?

Answer 13

An amino acid that releases serotonin and is used to reduce aggressive tendencies in juvenile delinquents.

Question 14

What is the key study regarding neural mechanisms and what was found?

Answer 14

Passenonti et al (2012)

• Altered the serotonin levels in healthy PP’s by manipulating their diet to contain no or normal levels of Tryptophan.
• Given a questionnaire to measure aggressiveness.
• A low serotonin level day meant communication between the pre frontal cortex and the Limbic System was weaker compared to a normal day.

Question 15

Give some evaluative points of neural factors?

Answer 15

• Is not a complete explanation as it does not effect everybody as low levels of serotonin do not make everybody aggressive.
• Ignored external factors such as the environment.
• Biological vulnerability and social factors are the best explanation to date.

Question 16

What role does testosterone play in aggression?

Answer 16

It is the make sex hormone and is thought to influence aggression as it effects the area of the brain involved e.g. Amygdala

Question 17

In regards to testosterone, what did Dabbs et al find?

Answer 17

Found that makes with high levels of testosterone had a history of violent crime compared to low levels having non violent.

Question 18

What is the key study regarding hormonal factors and in particular testosterone?

Answer 18

Van Goozen et al (1994)

• Completed questionnaires to assess aggression.
• Received hormonal treatments to ‘change’ their sex over 3 months.
• Found an increase in aggression when changing from female to male.
• Found a reduction when went male to female.

Question 19

Give a few evaluative points regarding hormonal mechanisms?

Answer 19

• Reductionist explanation as a complex behaviour is converted to a simple one.
• Ignores other factors such as social learning (Bandura)
• Klinesmith (2006) found aggression caused high levels of testosterone.