3.3.1 - Raine et al. (1997) Brain abnormalities in murderers indicated by PET

Question 1

what was the aim of the study?

Answer 1

in a pilot study by Raine et al. on 22 pps pleading ‘not guilty by reason of insanity’ (NGRI) and 22 controls, there was a significant difference in the activity of the pre-frontal cortex
therefore, Raine et al. hypothesised that pps pleading NGRI would show dysfunctions in brain areas associated with violence eg. prefrontal cortex, amygdala, angular gyrus

Question 2

what is the angular gyrus?

Answer 2

part of the parietal lobe associated with memory, language, processing and attention

Question 3

what was the sample for the study?

Answer 3

two groups of 41 people (39 males, 2 females)
experimental group were 41 criminals with convictions for murder or manslaughter being tested to gain evidence to support claim of NGRI
experimental group had variety of mental health problems/neurodisabilities eg. schizophrenia, epilepsy, brain damage/head injury

Question 4

what was the procedure for the study?

Answer 4

pps in experimental group didn’t consume any medication for two weeks before the scan
control group were matched with experimental group on age and gender
all pps screened for general health (physical examination, access to medical history, psychiatric interview)
pps excluded if they had history of seizures, head trauma and substance misuse
consent obtained from all pps before scan
1. pps given continuous performance task (CPT) to complete, consisting of a sequence of blurred numbers to focus on
2. CPT started as a practice trial 10 mins before FDG was injected
3. 32 minutes after FDG injected, PET scan was taken to measure metabolic rate in different brain areas to look at activity levels in those areas

Question 5

what were the results of the study?

Answer 5

brain dysfunction in the NGRI group did occur in areas associated with violent behaviour
specifically, experimental group had:
lower activity in prefrontal cortex
lower activity in parietal areas including left angular gyrus
asymmetrical activity in amygdala (lower in left, higher in right)

Question 6

what did the researchers want to emphasise about the study?

Answer 6

that the results don’t show that the experimental had no free will at all, and PET scanning shouldn’t be used to predict who will be a murderer

Question 7

what were the conclusions of the study?

Answer 7

brain differences have been associated with behavioural changes which could link to violent behaviour eg. dysfunction in pre-frontal cortex is linked to impulsivity and an inability to learn from the consequences of behaviour

Question 8

evaluation - generalisability?

Answer 8

strengths:
sample was the largest of violent offenders to be studied in this way
used humans instead of animals
experimental group had range of mental health problems/conditions

weaknesses:
only used murderers pleading NGRI, so not representative of all violent individuals
murderers show extreme aggression so findings aren’t generalisable to aggression in general population
sample was all-American and mostly male

Question 9

evaluation - replicability and reliability?

Answer 9

strengths:
standardised procedure used so others can follow
study was well-reported allowing findings to be compared

weaknesses:
we don’t know the age range of the sample
we don’t know how participants were recruited

Question 10

evaluation - objectivity?

Answer 10

strengths:
used quantitative data so findings were objective
standardised procedure so less open to researcher bias

weaknesses:
PET scanners in 1997 had poor spatial resolution so researchers may have had to use own judgement in some cases

Question 11

evaluation - validity?

Answer 11

strengths:
experimental group kept medication-free for two weeks before scan - controlling extraneous variables
identified that there were differences in brain structure and function between groups which was the aim, so it has high internal validity

weaknesses:
compared violent criminals with non-violent non-criminals - should’ve also included group of non-violent criminals to show that brain differences influence aggression specifically, not just criminality as a whole

Question 12

weaknesses - variation in procedure?

Answer 12

may be variation in procedure for different pps because the PET scan image are often taken based on the location of certain brain landmarks in each individual

Question 13

weaknesses - extraneous variables?

Answer 13

we can’t be sure that brain dysfunction does relate to behaviour - extraneous variables eg. social or situational factors may be what influences violent behaviour and/or brain dysfunction

Question 14

issues and debates - ethics?

Answer 14

1. murderers took part in research to build evidence to claim NGRI - may have been under pressure from counsel to take part
2. if murderers were actually mentally ill, we should question their capacity to consent (aim was to establish they had diminished capacity)
3. murderers were referred or psychiatric disorders which likely weakened their ability to give full consent

Question 15

issues and debates - socially sensitive research?

Answer 15

1. research suggesting criminality is determined biologically could imply offenders aren’t in control of their behaviour, therefore suggesting we should decriminalise certain offences
2. research could suggest that we can use brain scans to detect violent offenders so we can predict future offences and implement intervention strategies, however it may be that the violent offending leads to the change in brain function