key twin study!

• what is the key twin study in biopsychology?

  lacourse et al - 2010.
• lacourse - aim/focus!


  looked at physical aggression in twins and how and why it may develop.
• lacourse - sample.


  over 600 twins - around 250 mz twins and around 410 dz twins from Quebec longtitudinal study.
• lacourse - rough procedure. 


  mums of twins had to rate aggression at different age milestones - at nearly age 2, nearly age 3 and at 4 and a half.
• lacourse - findings.


  mz twins more likely to have same score on physical aggression than dz twins - suggests there is a genetic component. mz twins also showed the same expressions of aggression as aggression rose with age.
• lacourse - conclusion.


  conclude there is a genetic factor in aggression.
• lacourse - g.


  not very as twins and Canadian but very large sample!
• lacourse - r.


  very replicable. lack of controls with mum rating - inaccuracy.
• lacourse - a.


  apply to intervening aggression or identifying signs.
• lacourse - v. 


  lack of internal validity by rating behaviour due to risk of social desirability bias. ecological validity as child's behaviour was authentic due to not knowing mum was watching and rating.
• lacourse - e.


  yes ethical but socially sensitive to rate aggression.
• lacourse - I + d.


  practical issues - issues with rating behaviour particularly if it is a mum but also correlational research. reductionism - only rates behaviour and does not look at other factors like personality or other biological reasons.