brengden

Question 1

what was brengdens aim?

Answer 1

• to discover if there was a difference between physical and social aggression in 6 year old twins

Question 2

what was brengdens sample?

Answer 2

• 234 pairs of twins from the quebec newborn twin study (longditudinal)

Question 3

what does MZ mean?

Answer 3

monozygotic twins - identical

Question 4

what does DZ mean?

Answer 4

dizygotic twins - non identical

Question 5

what was brengdens procedure?

Answer 5

• children were entered into the quebec study when they were born, brengden obtained data when they were 6 with consent from parents
• teachers questionnaires were asked to rate a child on a 3 point scale on six questions
• peer ratings were conducted and children were asked to circle the three photos of who was most likely to do something on four questions

Question 6

what is an example of one of brengdens physical aggression questions for the teachers?

Answer 6

‘how likely is this child to get into fights?’

Question 7

what is an example of one of brengdens social aggression questions for the teachers?

Answer 7

‘how likely is this child to spread rumours about another’

Question 8

what is an example of a physical aggression and verbal aggression question for brengdens peer ratings?

Answer 8

‘who tells mean secrets’ - social
‘who hits other children’ - physical

Question 9

what were brengdens results?

Answer 9

• a chi squared test was conducted showing there was no significant difference between physical and social aggression, however there was a moderate correlation between teacher and peer ratings. boys were voted as more aggressive and MZ correlations were twice as high

Question 10

what were brengdens conclusions?

Answer 10

• 50-60% of physical aggression is linked to genes
• 20% of social aggression is linked to genes
• non shared environments account for the other 40 and 60%
• shared environments such as parenting technique accounts for the other 20% in social agression

Question 11

how generalisable is brengdens research?

Answer 11

• large sample size of 234 pairs however they were only 6 years old, so not very generalisable

Question 12

how valid is brengdens research?

Answer 12

• identical twins share 100% of the same DNA and non identical twins share 50% but have the same upbringing which makes her study valid for studying nature vs nurture
• it is a natural experiment so it cannot show clear cause and effect

Question 13

how ethical is brengdens study?

Answer 13

• written consent was obtained from all parents
• can a 6 year old give consent?

Question 14

how reliable is brengdens study?

Answer 14

• questionnaires are easily replicated and 2 researchers visited each classroom giving high inter - rater reliability rates
• there was a language barrier and children may mix up MZ twins when circling who is most likely to

Question 15

how applicable is brengdens research?

Answer 15

• early intervention classes can be given if social aggression is linked to the environment
• parenting techniques as 20% of social aggression is linked to shared environments