Brendgen - twin + contemporary study

Question 1

aim

Answer 1

this study was interested in the origins of social aggression.
the researchers set out with three key aims:
- to see if social aggression could be caused by genes or the environment
- to see if social aggression shared the same cause as physical aggression
- to see if one type of aggression leads to another type

Question 2

sample

Answer 2

• recruited from the Quebec Newborn Twin Study (QNTS)
• all pairs of twins born between november 1995 and july 1998
• 234 pairs of twins: 44 male MZ, 41 DZ males, 50 MZ females, 32 female DZ

Question 3

procedure - data

Answer 3

• Brendgen got written consent for the remaining twin pairs from their parents
• gathered data through giving surveys to schools, some were french-speaking and others were english-speaking so surveys were translated
• data gathered longitudinally at 5, 18, 30, 28 and 60 months and then again at 6 years, researchers focused on the final lot of data in this study
• ratings given by teachers and students were gathered in the spring term of the school year to ensure the twins were well known by those providing ratings for them

Question 4

procedure - teacher ratings

Answer 4

• teacher ratings were based on agreement with six statements, e.g. ‘to what extent does the child try to make others dislike a child’, ‘to what extent does the child get into fights.’
• scores were given on a 3-point scale by teachers (0 = never, 1 = sometimes, 2 = often)

Question 5

procedure - peer ratings

Answer 5

• each child in the twins’ class was given a booklet containing photos of every chid in the class and they were then asked to circle three pictures of children that they thought matched four different behaviour descriptions, e.g. ‘tells others not to play with a chid’, ‘gets into fights.’
• each twin was then given a social and physical aggression score based off both the teacher and peer ratings

Question 6

results

Answer 6

• higher correlation in MZ then same sex DZ twin pairs for physical aggression, equally correlated for social aggression
• results of aggressive tendencies in general is a result of genetic factors, but the way these tendencies are expressed is more dependant on environmental factors
• data suggested that physical aggression may lead to social aggression, but not the other way around

Question 7

results - data

Answer 7

• teacher ratings: social aggression 20% genetic, 80% environment and physical aggression 63% genetic and 37% environment
• peer ratings: social aggression 23% genetic, 77% environment and physical aggression 54% genetic and 46% environment

Question 8

conclusion

Answer 8

• the expression of aggressive tendencies may change as children grow and learn more ‘socially acceptable’ ways to show aggression
• there seems to be a strong genetic component to physical aggression but not social aggression as this is more likely to be due to environmental effects

Question 9

strengths

Answer 9

• sample: high validity. large sample of 234 twin pairs. therefore, if anomalies occur for children with very high or low levels of aggression they can be averaged our by the size of the data, this making results more valid.
• procedure: high reliability due to a standardised procedure. peer rating sociometric procedure took about 45mins per class. same 6 statements given to all teachers. therefore, we can easily repeat this study to check for consistency in findings for the origins of aggression as shown in MZ and DZ twin pairs.
• results: high validity. quantitative and therefore objective, correlations were used. therefore, results will be free from bias which will increase their accuracy.

Question 10

weaknesses

Answer 10

• sample: low generalisability. ethnocentric as all from Quebec and 6 years old during study. therefore, results may not be representative of what the origin of aggression may appear to be in other ages, e.g. social aggression doesn’t really develop until age 8 and not representative of other cultures.
• procedure: low ethics. students had to look at pictures of their classmates and judge them, this would have a bad impact on friendships - especially if the children speak about who they circled for the statements - and can lead to hurt feelings. therefore, this goes agents the social responsibility of ethical research and suggests that this study may not be repeatable.
• results: low validity. cause and effect cannot be established with correlations as they don’t show causation. there may be another variable, e.g. formed stereotypes based off identical looks in MZ twins leads to higher concordance rates. therefore, there is decreased accuracy in results.

Question 11

application

Answer 11

high application. if friends and family are a big influence on social aggression, it suggests that educating parents into being better role models and improving the way they handle their children can prevent the children romantically becoming socially aggressive with their own friends. therefore, we can help to better society as well as the children’s quality of life.