What is the difference between Nature and Nurture?

Nature = Genetic Inheritance

Nurture = Environmental Influence

What is the difference between identical and non-identical twins?

Identical twins share all the same genes

Non-identical twins only share 50%

How do researchers utilise twin studies?

Compare the degree of similarity of aggressive behaviour between identical twins and non-identical twins. If the identical twins are more alike, then this is due to genetics rather than environment. 

Name a Psychologist investigating aggression through twin studies?

(Initials: C)

Coccaro et al.

What did Coccaro et al. show about aggression through twin studies?

In adult twins, nearly 50% of the variance in direct aggression towards others could be attributed to genetic factors.

What kind of study can be used to differentiate between genetic influence and environmental influence?

Adoption Studies

How can adoption studies show if genetics are the cause of aggression?

If a positive correlation is found between the child's aggressive behaviour and the biological parents' aggressive behaviour, then a genetic cause is implied.

How can adoption studies show if the environment is the cause of aggression?

If a positive correlation is found between the adopted child's aggressive behaviour and the adoptive parents' aggressive behaviour, then an environmental cause is implied.

Although no specific gene responsible for aggression has been found, what has been identified instead?

A gene responsible for producing the protein MAOA

which has been associated with aggressive behaviour.

Why is MAOA associated with aggressive behaviour?

MAOA regulates the metabolism of seretonin and low levels of seretonin have been associated with aggression.

Name a Psychologist investigating the role of MAOA in aggressive behaviour? 

(Initials: C)

Caspi et al.

How did Caspi et al. investigate the role of MAOA in aggression?

Studied 500 male children and found those with low levels of MAOA were more liekly to grow up and exhibit aggressive behaviour, but only if they'd been maltreated. Those with high levels of MAOA didn't display aggression, regardless of whether they'd been maltreated or not.

What levels of MAOA are associated with aggressive behaviour?

Low

What has research shown about the role of genes in increasing crime levels in adopted children?

Research has shown that the highest rates of criminal violence occur in adopted children when both the biological, and the adoptive parents have a history of crime.

Why might crime levels in adopted children increase if both the biological and adoptive parents have a history of criminal violence?

Incorporates both genes and the environment coupled together to enhance aggressive behaviour.

Name 3 Psychologists supporting the role of Genetics in Aggression?

(Initials: H&M, B, Y)

Hutchings & Mednick

Brunner et al.

Young et al.

Why do Hutchings and Mednick support the role of genes in Aggression?

Found that a significant number of adopted boys with criminal convictions also had biological parents with criminal convictions.

Why does Brunner et al. support the role of genes (MAOA) in Aggression?

Studied a Dutch Family and found that the male members displayed aggressive/violent behaviour including rape/arson and also had low levels of MAOA suggesting that this was the cause of their aggression.

Why does Young et al. support the role of genes in Aggression?

Identified a genetic mutation in mice, causing violent/aggressive behaviour towards one another. A counterpart of this has been found in humans but but it's precise function is unknown.

Why might Young et al.'s study be at fault?

Whilst a counterpart of the genetic mutation found in mice, was also found in humans - it's precise function is unknown.

Name 2 Psychologists criticising the role of genes in Aggression and 2 IDA points?

(P, W, MI, GR)

Plomin et al

Walters

Methodological Issues

Gene Research Issues

Why does Plomin et al. criticise the role of Genes in Aggression through twin studies?

Found no differences in aggressive correlations between identical and non-identical twins suggesting individual differences are due to environmental influences instead.

Why does Walters criticise the role of Genes in Aggression?

Conducted a meta-analysis of studies investigating the role of genes enhancing crime. Found only low->moderate correlations between the two.

What are the 2 methodological issues associated with the role of genes in aggression?

A lot of research relies on parental or self-report techniques and inidividuals may not always tell the truth.

Also fails to distinguish between violent aggression and non-violent aggression. Even cases of these, may just be one-offs.

What are the implications of Gene research associated with Aggression?

More than one gene usually contributes to a behaviour and often, this is usually down to the environment anyway.