contemporary study: examining genetic and environmental effects on social aggression: a study of 6-year-old twins (Brendgen et al., 2005)

Question 1

background

Answer 1

• they studied social aggression, which includes manipulative behaviours like ignoring, spreading rumors, or threatening to withdraw friendship
• social aggression can be overt or covert

Question 2

aims

Answer 2

• to determine if social aggression is caused by genes or environment
• to see if social aggression shares the same cause as physical aggression
• to explore if one type of aggression leads to another type

Question 3

what was the sample and method used in brendgen et al study on social aggression?

Answer 3

• ppts were twins from the Quebec Newborn Twin Study (QNTS), born between 1995 and 1998
• 322 pairs of twins were tested, but complete data was gathered on 234 pairs
• sample included MZ (monozygotic) and DZ (dizygotic) twins, both same-sex and mixed-sex
• data was collected longitudinally at ages 5, 18, 30, 48, 60 months, and again at 6 years
• data was gathered via two ratings of each twin’s behaviour, one from teachers and one from classmates, in the spring term for familiarity

Question 4

how were teacher and peer ratings gathered in brendgen et al study on social aggression?

Answer 4

• teacher ratings were based on statements from the Preschool Social Behaviour Scale (PSBS-T) and Direct and Indirect Aggression Scales
• teachers rated statements like “To what extent does the child try to make others dislike a child?” (social aggression) and “To what extent does the child get into fights?” (physical aggression) on a 3-point scale (0-never, 1-sometimes, 2-often)
• peer ratings were done by giving classmates a booklet with photos of each child in the class and asking them to circle three pictures that matched four behavior descriptions (e.g., “Tells others not to play with a child” for social aggression, “Gets into fights” for physical aggression)
• each twin was given a social and physical aggression score based on teacher ratings and peer selections

Question 5

what were the initial findings of brendgen et al study on aggression?

Answer 5

• there was a higher correlation between MZ (monozygotic) twin pairs on physical aggression compared to same-sex DZ (dizygotic) twin pairs
• this was true for both teacher and peer ratings of physical aggression
• social aggression scores were similarly correlated in both MZ and DZ twin pairs
• findings suggest that physical aggression may be influenced by genetic factors, while social aggression may be influenced by shared environmental factors

Question 6

what did brendgen et al find in relation to the second aim of their study on aggression?

Answer 6

• correlation was found between physical and social aggression in the children
• correlation was best explained by genetic factors rather than shared environmental factors
• this suggests that aggressive tendencies may be genetically influenced, but how these tendencies are expressed may depend on environmental factors, eg exposure to others’ aggressive behaviours

Question 7

what did brendgen et al find in relation to the third aim of their study on aggression?

Answer 7

• data suggested that physical aggression may lead to social aggression, but not the other way around
• they concluded that the expression of aggressive tendencies changes as children grow
• as children develop language and cognitive skills, they may learn more socially acceptable ways to express aggression
  -+younger children may express aggression physically, but as they grow, they may express it socially (eg through manipulation or verbal aggression)

Question 8

conclusion

Answer 8

• strong genetic link to physical aggression
• social aggression more influenced by environment
• physically aggressive children may show social aggression due to gene-environment interaction
• as children grow, social aggression increases due to social rules on physical violence and new ways to express themselves

Question 9

weakness (gen)

Answer 9

• small sample sizes make generalising results difficult
• sample may not represent the entire population
• small sample due to time-consuming data collection with 6-year-olds (can’t read or write independently so researchers had to be with them individually)
• results can’t be applied to the wider target population

Question 10

weakness (gen)

Answer 10

• study focused on a specific age group (6-year-olds)
• aggression may develop differently in other age groups
• physical aggression decreases when children start school (Nagin & Tremblay)
• social aggression develops later, around age 8 (Bjrouist, Lagerspetz et al)
• results can’t be applied to the wider target population

Question 11

strength (reliability)

Answer 11

• all ppts followed a standardised procedure
• teachers rated children using consistent scales (pre-school social behaviour scale, direct/indirect behaviour scale)
• this ensures consistency and reliability of the study’s findings

Question 12

strength (application)

Answer 12

• findings could help prevent the development of social aggression
• early indicator of physically aggressive children allows for early intervention
• tackling aggression in young children is easier than in older children with established behaviour
• study can explain and address real-life behaviour problems

Question 13

strength (val)

Answer 13

• used two sources to measure aggression: teachers and peers
• validating findings by comparing data from both sources
• teachers and peers agreed, reducing bias
• strengthens the validity of the findings, ensuring the study measures what it aims to