contemporary study.

• who did the study and when?

  brengden et al in 2005.
• brengden - aim.

  to investigate to what extent both social and physical aggression can be explained by genetic and social influences. also, to see whether they overlap as a result of a direct influence of either onto the other (physical leads to social for example).
• brengden - sample.

  twins from the Quebec longitudinal twin study. used 44 mz twins (m) and 41 dz (m). used 50 mz (f) and 32 dz (f). used more but not used in final analysis.
• brengden - procedure.

  involved teachers rating likeliness of social and physical aggression by saying never, sometimes or often. also, after kids were checked that they knew their classmates by a researcher, they were given a booklet and asked to match 3 peers to descriptions.
• brengden - findings.

  teachers rated social aggression to be genetics 20% of the time while peers rated 23% - means identical twins are equally as likely in amount of social aggression. found that high physical aggression often led to high social aggression but not the other way. found physical to be more genetically explained while social was environmental like hanging with the wrong crowd.
• brengden - conclusion.

  although there is genetic predisposition to aggression, we can conclude that physical aggression is much more influenced by genetics. children that are physically aggressive are more likely to show social aggressive signs at around age 6.
• brengden - g.


  large sample but Canadian and twins so not very representative.
• brengden - r.

  very replicable and reliable. control over researcher checking kids knowledge of peers.
• brengden - a.

  application to early intervention and therefore treatment to stopping aggression early.
• brengden - v.

  there is some ecological validity as it is based on class atmosphere. but issues with rating behaviour as there may be bias although results were very similar. issues with assuming they grew up in same environment or are similar just because they are twins however derks et al argued it does not matter if they are identical or had shared same environment or not as it doesn't impact correlation.
• brengden - e.

  not really!