Brendgan (twin study)

Cards (34)

  • what is physical aggression?
    violence towards to another person
  • what are examples of physical aggression?
    hitting, kicking, biting, punching
  • what is social aggression?
    verbal violence towards a person
  • what are examples of social aggression?
    gossiping, spreading rumours, criticising others behind other people
  • what were Brendgen aims?
    • to see if social aggression is caused by the environment
    • to see if social aggression shares the same causes as physical aggression
    • to see if one type of aggression could cause another
  • what was the sample size that had data collected on them?
    234 pairs of twins
  • how many were identical twin pairs?
    94 identical twin pairs
  • how many twin pairs had DNA tested to check if monozygotic otr dizygotic ?
    123 pairs of twins
  • what were the results of the DNA testing?
    94% of the assignments assumed were correct
  • what were the methods of sorting pairs into monozygotic and dizygotic?
    physical resemblance and questionnaires
  • what does it mean by a longitudinal study?
    the study followed all the twin pairs over a long period of time
  • over what time length was the data on the twins collected ?
    6 years
  • how any classrooms were involved in the experiment?
    409 as some twins in separate classes
  • what did the experimenters use to gather data from teachers and peers?
    standardised questionnaires
  • how did the teachers rate the aggression?
    completed questionnaires with scales of 0= never 1=sometimes and 2=often
  • what was an example for a teacher measuring a twins social aggression?
    "tries to make other dislike a child"
  • what was an example for the teachers measuring a twins physical aggression?
    "gets into fights"
  • how did the peers measure the twins aggression?
    given photographs and asked to circle the 3 children who fitted the descriptions the most
  • what was an example of social aggression statement given to the peers?
    "tells others not to play with another child"
  • what was an example of physical aggression statement for peers?
    ""hits, bites or kicks others"
  • what ages were the twins when the researcher gathered evidence?
    5 months, 18 months, 30 months, 4yrs, 5yrs, 6yrs old
  • what were the results for physical aggression?
    positive correlation between MZ twins was much higher than the DZ same sex twins for
  • what was the conclusion for the physical aggression correlation for MZ and DZ twins
    for 6 years old 50-60% of aggression is linked to genes
  • what were the result for the social aggression?
    correlation between MZ twins for social aggression was the same for the DZ twins
  • what was the conclusion for the social aggression?
    only 20% of social aggression is genetic (60%) from non-shared environment
  • does one type of aggression lead to another type of aggression?
    yes, physical aggression can lead to social aggression.
    • cannot happen the other may around
  • what was the conclusion for the physical leading to social aggression?
    perhaps the children learnt that the physical aggression not socially acceptable and found they coulld get away with social aggression
  • what was negative about the generalisability of the study?
    • limited age range of 5 months to 6 years cannot generalise beyond that
    • twins are not typical of normal siblings- unusual closeness
  • what was positive about the generalizability?
    large sample group of twins and so is representative
  • what was good about the reliability of the study?
    rating scales were standardised and had good internal reliability
  • what was negative about the reliability?
    the scales had to be translated into French for some teachers and peers therefore possible to get things lost in translation
    • but there was a translator who verified it
  • what was positive about the validity of the study?
    peer and teacher ratings were consistent - reducing bias
  • what was negative about the validity?
    identification of some of the twins were based on the physical appearance and questionnaires alone with no DNA to back it up.
  • what were the ethics in this study?
    • informed consent was given by the parents as the children were under 16 years old
    • the research was found to be socially sensitive research as it has a danger of labelling and creating a self-fulfilling prophecy by identifying a 6 year old as being genetically aggressive