Brendgen Et Al. Flashcards
When did Brendgen et al conduct their study?
2005
Where was the study conducted?
In Quebec, Canada at the University of Montreal
Aim
To examine the genetic and environmental influences on physical and social aggression; if there’s a different between both and wanted to see if physically aggressive kids are also socially aggressive
Who did they compare?
MZ and DZ twins
Sample
234 6 year old Canadian twins who were from Quebec Newborn Twins Study.
94 MZ same sex twins, 73 DZ same sec twins and 67 DZ mixed sex
Method was Opportunity sampling
Procedure
teachers were given questionnaires which had 6 statements and asked to rate children based on their aggression
students were then given picture of other children in the year and then told to circle three people who matched the following descriptions of aggression
what statements were included in the questionnaires given to the teachers?
social aggression : tries to make other dislike a child, say bad things or spread nasty rumours about another child
physical aggression : gets into fights, physically attacks others and hits, bites or kicks others
what descriptions were included in the peer rating material given to the children
social aggression : tells others not to play with a child, tells mean secrets about another child
physical aggression : gets into fights and hits, bites or kicks others
How could the teachers data and peers data be combined?
Brendgen carried out a chi squared test and found the difference between both sets of rating to be insignificant. She also found a strong correlation between how the teacher rated each child’s aggression and how the child’s friends rated it, suggesting the two views were in agreement, making them more valid.
what can be concluded?
- 50 - 60% of physical aggression can be linked to genes due to MZ twins having a higher correlation than DZ twins
- 20% of social aggression can be linked to genes
- non shared environment was also considered as an influence and seemed to account for 40 % of physical aggression and 60% of social aggression
- 20% of social aggression could be accounted for by shared environment
- it was pointed out that if parents withheld love and affection to control children, children would do the same with peers
- data suggested physical aggression may lead to social aggression but not social aggression leading to physical aggression.
generalisability
sampling validity : a mixture of male and female ppts were used however, all ppts were aged 6 and 88 pairs of twins disappeared from the Quebec Newborn Twins study before aged 6
reliability
- standardised materials used eg: questionnaires all had the same statements to measure physical and social aggression
- strong correlation between how peers and teachers rated so, more accurate and more valid
- inter - rater reliability as two researchers in every room
objectivity
- childrens actions may be subjective and open to interpretation
- genetics test weren’t conducted on all children to test if they were MZ or DZ twins as they relied on visual judgement
- the rankings used by both peers and teachers were numerical so can be easily be compared
validity
- high validity; questions used in teacher and peer ration materials are good measure of physical and social aggression
- social desirability issues; may want to protect their more aggressive friends therefore may not answer truthfully
- teacher may not see how child interacts out of classroom with others
- child who is said to be aggressive may not actually be aggressive and could be under a bad influence
- kids may mix up twins
- no demand characteristics as children were unaware of being in a study
ethics
- presumptive consent obtained from parents and children
- the peer - rating method may cause issues as you had to look at picture and judge classmates and this may have an impact on friendships especially if children told eachother that they said about one another and this could lead to hurt feelings which goes against social responsibility of ethical research
