Brendgen - Twin study Flashcards
What was the aim?
To see is Schizophenia is genetic and more prevalent in the biological families of Schizophrenics or the adopted families
What was the sample?
234 twin pairs (originally 322) from Quebec
123 of the twin pairs were genetically tested to check zygosity- what % agreement was there with the researchers assignment?
94%
What were the teachers asked to do?
Rate the children on social and physical aggression questions on a 3 point scale of often, sometimes, never
What questions were they asked?
e.g. how often do they hit, bit or kick another and for social aggression how often they become friends out of revenge
What were the children asked to do?
Circle pictures of the three children in class most likely to meet certain behaviour characteristics
Which of these are descriptors used?
e.g. tells mean secrets about another child and gets into fights
What were the results about physical aggression?
There is a much higher correlation (nearly double) between MZ than between DZ twins on Physical aggression
What were the results about social aggression?
The correlation between the MZ twins was similar to that of the DZ twins
What is the relationship between physical and social aggression?
There was a strong positive correlation on teacher ratings between social and physical aggression (0.79)
What causes physical aggression?
Genetics
What causes social aggression?
Environment
What is a strength of the sample?
It is a large sample of twins which makes the study more generalisable
What is a weakness of the sample?
It is ethnocentric as all the children were from quebec in canada which means the results about genetics might not apply to other cultures
Is the reliability of Brendgen good or bad?
The tests the teachers and students did were standardised AND comparing teacher and child scores means we have inter-rater reliability
