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Biological - Raine (1997) - Coggle Diagram
Biological - Raine (1997)
Results
NGRI's showed less activity in the prefrontal cortex, which is associated with self restraint, rational thinking and memory
NGRI's showed less activity in the corpus callosum (the bridge between the left and right hemispheres), which is associated with long term planning
NGRI's showed less activity in the parietal lobe, which is associated with abstract thinking (morality, ethics, justice etc)
NGRI's showed more activity in the occipital lobe, which is associated with vision
Conclusions
Raine concludes that findings from animal studies into aggression can be generalised to humans and there is a link between brain structure and aggression.
Deficits in the corpus callosum make it harder for the brain’s hemispheres to communicate, making it difficult to think through long term consequences and make decisions
Prefrontal deficits might make someone more impulsive and emotional
Procedure
This is a natural experiment, since Raine obviously didn't have anything to do with the murderers' actions
Sample
41 NGRI's pleading not guitly to murder and 41 controls
NGRI's were 39 men & 2 women and had a mean age of 34. 6 of them had schizophrenia
The control group were the same age & gender. 6 of them also had schizophrenia
This is an opportunity sample
Participants were injected with the glucose tracker and then performed the continous performance task for 32 mins. After that they had a PET scan.
Raine made sure all of them were medication free for 2 weeks before the PET scan
They practiced the continuous performance task for 10 mins before the glucose tracker injection so that they were familiar with it
Aims
To see if there's difference between the brain activity of someone who's committed murder (NGRIs) and non-murderers
To see if studies on brain activity and aggression on animals also apply to humans
Evaluation
Strengths
Has high internal validity due to the control of extraneous variables
He ensured that all participants were medication free 2 weeks prior to the PET scan.
This is a strength because Raine can be confident that differences in Brain activity between NGRI’s and the control group weren't affected by medication, thus cause and effect conclusions are more accurate.
Is applicable
NGRI’s and controls had a difference of - 0.04 in their metabolic rate (glucose use) in the prefrontal cortex. This is related to NGRI’s lack of self control and failure to learn from consequences.
Therefore according to these findings monitoring at risk individuals with deficits in these areas could reduce aggression.
Weaknesses
A weakness is that despite using a large sample it could be argued to have limited generalisability.
NGRI’s aren't ‘normal criminals’. Some don't remember doing the crime or are too confused to stand for trial.
Therefore the NGRI sample may not be representative of ‘criminals’ as a whole
Ecological validity is a weakness because the CPT task is artificial.
Low ecological validity could be due to the participants doing an unnatural CPT task. Since this isn't a task most people do regularly, the participants brain’s might have reacted in an unnatural way.
This is a weakness because low validity may mean that the data gathered isn't accurate.