Classic Study - Raine (1997) Flashcards
1
Q
What is Positron Emission Tomography (PET)?
A
- brain imaging technique
- injecting glucose solution that dissolves in blood
- solution has been tagged with a radioactive tracer which will go to the brain
2
Q
Aim?
A
To find out if there is a difference in the structure of brain activity between people who have committed murder but were pleasing Not Guilty by Reasons of Insanity (NGRI) (from schizophrenia to head injuries) and non murders
3
Q
What area of the brain did Raine specifically look at?
A
Areas that may be linked to aggression
- prefrontal cortex
- corpus collosum
- amygdala
- medical temporal lobe (MTL)
- hippocampus
- thalamus
4
Q
What did Raine do to put all participants in a similar mental state during the scan?
A
- participants were given a continuous performance task (CPT)
- pressed a button when they heard a beep
- provokes concentration and activates prefrontal cortex
5
Q
IV
A
Whether participant was a NGRI or a non murderer
6
Q
DV
A
Relative glucose levels in the prefrontal cortex and other places of the brain as revealed by the PET scan
7
Q
What did the experiment look at?
A
- natural experimental method as participants with criminal background is a naturally occurring variable
- link between cognitive and biological psychology
8
Q
Sample
A
- 82 participants, 41 NGRI 41 controls
- NGRIS had 39 men and 2 women with a mean age of 34.3 (23 had a history of brain damage, 3 had history of drug abuse, 6 had schizophrenia, 2 had epilepsy, 7 with emotional and learning disorders)
- control were matched so they were people of the same age and sex of the NGRIS but had no history of crime or mental illness except for the 6 controls who had schizophrenia
- opportunity sample
9
Q
Procedure
A
- uni of California
- none of the participants were on medications and NGRIs were off meds 2 weeks prior to PET scan
- participants were allowed to practice the CPT 10 mins before injection so they were all equally familiar
- injected glucose tracer
- participants performed the CPT for 32 mins
- PET scan was carried out
10
Q
Results
A
- NGRIS showed less activity in the frontal lobe especially in the prefrontal lobe (rational thinking, restraint, memory)
- NGRIs showed less activity in the parietal lobe (morality and justice)
- NGRIs has less activity in the corpus callosum (long term planning)
- NGRIs had an imbalance of activity between left and right hemispheres as they had less activity on the left and more on the right in the amygdala, MTL and thalamus (aggression in animals)
11
Q
Conclusions
A
- prefrontal deficits (lack of activity) might make someone more impulsive and emotional
- deficits in the limbic system (amygdala, thalamus and hippocampus) might make someone aggressive
- deficits may make it hard for one to learn from mistakes and understand their emotions
- deficits in corpus callosum can make it harder for brains hemispheres to communicate so it will be difficult to think through long term consequences and decisions so they may act more impulsively
- deficits in amygdala and parietal lobe can make it harder for one to judge social situations which can lead to overreactions and therefore aggression
- findings from animal studies into aggression can be generalised to humans
- findings can only be generalised to NGRIS not al violence
- violence is not purely biological as social and environmental factors play a part
- prefrontal dysfunction does not mean you will be a criminal offender
- results do not show that NGRIs had no free will
- not all murders are violent acts and not all NGRIS were accused of violent murders (poisoning) therefore cannot link brain deficits with violence
12
Q
Generalisability
A
- population validity due to robust sample size so any anomalies would not skew data significantly
- not representative of wider population as we are only told about NGRI murders
- androcentric as there were only 2 females to 39 males in both groups so can’t generalise to female population
- all were from California so there is a culture bias therefore can’t generalise to other regions
13
Q
Reliability
A
- PET is reliable technology which produces objective and replicable results
- CPT ensures similar brain activity producing reliability
- standardised procedures as whole procedure can be replicated
- there was some problems with the PET scanner therefore less accurate results so less reliable
- PET scans can be difficult to interpret which makes it subjective therefore lowers reliability
14
Q
Application
A
- if damage that causes these defects can be prevented then people may be prevented from committing murder as they don’t develop a murderous predisposition (tendency)
- encourages early intervention with children to steer them away from drugs as it may cause brain deficits which can lead to murderous predisposition
- experiment encourages monitoring those with brain damage
- if deficiencies can be treated or stimulated with drugs then people may be less likely to engage in impulsive aggressive behaviour
15
Q
Validity
A
- Bufkin and Luttrell (2005)
- Yang and Raine (2009)
- CPT can be argued to be artificial and unconnected to the study on violence which lowers validity
- natural study so doesn’t show cause and effect
- can be argued that the NGRIS developed the deficits in the brain after the murders due to stress of trial
- study only looks at brain activity so it is reductionist as from one perspective and ignores other factors
