Contemporary Brendgen 2005 Flashcards
aim of brendgen 2005
- is social aggression caused by genes or environment
- are social aggression and physical aggression caused by the same factor
- does one type of aggression lead to another
sample of brendgen 2005
- 234 twins (322 originally recruited but high dropout rate)
- recruited from Quebec Newborn Twin Study
- 94 MZ twins
- 140 DZ twins
procedure of brendgen 2005
- data gathered longitudinally from ages 5 months to 6 years old, questions were originally in French
- questionnaires done in spring term
- teachers and peers given questionnaires where they had to rate each twin’s behaviour
- Teacher ratings: had to state how much they agreed with 6 statements from ‘Preschool Social Behaviour Scale’ and ‘Direct and Indirect Aggression Scale’ using a 3-point Likert Scale
- Peer ratings: children given booklet containing photos of each child from class, had to circle 3 pictures of children they thought matched 4 different behaviour descriptions e.g. ‘gets into fights’ (physical), ‘tells others not to play with a child’ (social)
results of brendgen 2005
0.79 positive correlation between MZ twins on physical aggression
teacher ratings:
- 63% of physical aggression could be accounted for by genetic factors in MZ
- 80% of social aggression could be accounted for by environmental factors
peer ratings:
- genetic and shared environmental factors accounted for 23% of each aggression
conclusions of brendgen 2005
- strong genetic component to physical aggression but not social
- social aggression more likely due to environment
- more physically aggressive children more likely to be socially aggressive
- as children grow, they become more socially aggressive rather than physically due to social norms
generalisability of brendgen 2005
Low
- sample attrition occurred as 322 pairs of twins were originally recruited but only 234 were completely evaluated
- causes narrow sample size especially due to specific age group of 5 months to 6 years
- also ethnocentric as only from Quebec Newborn Twin Study
reliability of brendgen 2005
High
- standardised scoring system for aggression used on Teachers and Peers e.g. 3-point Likert Scale for whether they agreed with 6 statements on behaviour, circling face of children that matched descriptions
- procedure can be replicated in other locations to test for consistency of results
validity of brendgen 2005
Low
- allocation of MZ and DZ groups was unscientific, twins were judged to be MZ/DZ through visual checks, only 123 were DNA assessed
- if they were incorrectly identified, validity is reduced
- self-report data was used so it is biased and subjective to the teachers/peers being assessed
High
- measures of twin’s aggressive behaviour was triangulated and came from two sources, adds to the internal validity of findings and highlights and eliminated bias as they were in good agreement with eachother
ethics of brendgen 2005
Fair
- correlations don’t involve manipulation of a situation so won’t cause psychological discomfort for ppts
- 88 pairs of twins dropped out so right to withdraw was practised
applications of brendgen 2005
provides ideas for early intervention to reduce aggression
- if social aggression is more influenced by environment, calmer classroom environments can be promoted
- ensures behaviours are appropriately punished/rewarded
