Findings and conclusions

• Weaknesses

  • Cannot infer causation
  • quasi-experiment does not allow for causal conclusions to be drawn between abnormalities and violent behaviour
  • IV was a pre-existing difference meant that Raine had no control over this or confounding variables
  • lowers internal validity as other factors may have influenced
  • Alternative evidence to contradict
  • Bandura conducted the bobo doll experiment
  • found that children who observed an aggressive role model were more likely to imitate that behaviour to the doll
  • suggests that behaviour is learnt rather than a biological explanation
• Strengths

  • High internal validity
  • use of PET scans allow for objective and detailed study of brain activity between the 2 groups
  • increases the internal validity as findings represent the actual differences in the brain activity
  • High internal validity
  • use of matched pairs designs means that ppts were matched on variables such as age, mental disorders, gender
  • this means Raine could control for some key ppts variables
  • meaning that we can assume any differences are due to the groups rather than the individual
  • this increases the internal validity