Biological Approach - Classic evidence: Raine, Buchsbaum and LaCasse (1997) Flashcards
1
Q
How does a PET scan work
A
- radioactive glucose is administered to the patient, then placed in a computer scanner
- The positrons smash into electrons –> releasing gamma rays
- the emission is detected by the scanner
- the detected emissions are plotted and the varying levels of activity in the brain are therefore recorded
- sometimes a 3D plot is produced
2
Q
what is a quasi-experiment
A
- The IV isn’t deliberately manipulated
2 types:
1) natural experiment: not possible to manipulate the IV
2) Difference study: IV naturally exists as a difference between people
3
Q
When describing the methodology, what 4 things would you write about
A
- Research method (Quasi)
- Design (matched pairs)
- participants
- Control group
- Sampling strategy
4
Q
describe the methodology in terms of Research method
A
- It was a Quasi experiment
- this means that its not a true experiment as the participants couldn’t be randomly assigned to 1 of 2 conditions
- the IVs were: NGRI or not
- the DV was: brain differences
5
Q
what is an NGRI
A
not guilty for reasons of insanity
6
Q
describe the methodology in terms of design used
A
- Matched pairs design
- each murderer was matched with a control participant of the same age and gender
7
Q
describe the methodology in terms of participants used in the experimental group
A
- 41 participants tried in state of California
- 39 men, 2 women
- mean age: 34.3
- all charged with murder or manslaughter
- subjects were referred to the University of California to obtain evidence using PET scanning to determine if guilty or NGRI. it also meant a potentially reduced prison sentence if they took part
- in 7 of these cases, there was also unusual circumstances surrounding the crime that additionally lead to the suspicion of some mental impairment
- all participants were medication free (checked with urine scan 2 weeks prior to brain scanning)
8
Q
describe the methodology in terms of the control group used
A
- formed by matching each murderer with a normal participant of the same sex and age –> tested identically with the exact same procedures in a laboratory
- made up of 41 participants (39 men, 2 women) mean age = 31.7
- They were screened for health with a physical exam, psychiatric interviews and their medical history was checked
- 6 schizophrenics in this group were matched with the 6 schizophrenics in the experimental group (the other controls had no history of psychiatric or significant physical illness)
- none were taking medication
9
Q
what was the sampling strategy
A
opportunity
10
Q
why was matched pairs design used
A
- reduce participant variables
- reduce order effects
11
Q
Describe the procedure
A
- PET scan was done to study the active brain of both murders and the controls
- The participants were given a chance to practise the CPT (continuous performance task).
- The CPT is designed to activate the parts of the brain that the researchers were interested in.
- Once the participants started the CPT, the fluorodeoxyglucose (FDG) was injected after 30 seconds
When a part of the brain is active, it metabolises glucose. So - Radioactive detectors in the PET scan can “see” the radioactive areas released from the FDG being metabolised, showing the researchers the active parts of the brain. - After 32 minutes a PET scan was done of each participant and 10 horizontal slices of the brain were recorded using a peel and box technique.
12
Q
what were the findings of the performance on CPT
A
- both groups performed similarly on CPT
–> suggests any difference in brain activity wasn’t due to performance on this task
–> IMPORTANT: so we know that differences observed were not related to the CPT
13
Q
What were the different findings recorded
A
- performance on CPT
- reduced/increased/no difference in activity of certain areas of the brain
14
Q
what was the findings for reduced activity
A
- reduced activity in the brain of NGRI participants, in areas previously linked to violence:
- prefrontal cortex
- left angular gyrus
- corpus callosum
- in the left hemisphere only there was reduced activity in the amygdala, thalamus and hippocampus
—> remember ‘Pac hat’
15
Q
what was the findings for increased activity
A
- increased activity in the brain of NGRI participants, in areas not previously linked to violence:
- cerebellum
- in the right hemisphere there was increased activity in the amygdala, thalamus and hippocampus
—> remember ‘Cath’
16
Q
what was the findings for no difference in activity
A
- no difference between NGRI group and controls, in areas not previously linked to violence
- Caudate
- Putamen
- globus pallidus
- midbrain
- remember it by ‘crazy people give paper money’
17
Q
describe some of the conclusions that can be drawn as a result of the findings
A
- less activity in the prefrontal cortex = Damage to this area can result in impulsivity, loss of self-control, immaturity and the inability to modify behaviour. This could in turn cause aggressive behaviour
- The amygdala, hippocampus, and prefrontal cortex make up part of he limbic system which controls the expression of emotion. These areas showed reduced activity in murders, which could explain the abnormal emotional response
- In animals, destruction of the amygdala = lack of fear. In the offenders = reduced activity in the amygdala = suggests less fear, making them less fearful of the consequences of their violent behaviour
18
Q
what is the overall conclusions
A
- Raine makes it clear that this doesn’t mean that murderers can’t be held accountable for their actions, nor that we can use PET scans to diagnose criminals
- It may be a violent lifestyle that causes changes in the brain, rather than the other way around
19
Q
If you were evaluating the methodology, what would be a strength (use PET paragraph)
A
- P: PET scans were used as a research method
- E: it was heavily standardised with timings (done 32 minutes after FDG was administered during the CPT). Allowed them to see various levels of activity in specific regions of the brain (red for high activity, blue for low activity)
- T: scans are scientific and provide solid, observable evidence of results meaning that Raine could show some sort of a cause-and-effect relationship between brain areas and violent crime
- COUNTER: the CPT had no mundane realism and didn’t replicate the same everyday emotions you feel when stabbing someone. Therefore the PET scan had low ecological validity
20
Q
If you were evaluating the methodology, what would be a weakness (use PET paragraph)
A
- P: there’s no causal relationship (cause and effect wasn’t observed)
- E: As Raine pointed out, findings don’t show that violence is due to biology alone. Other factors such as upbringing must influence violence
- T: Therefore causal conclusions aren’t justified. There’s a danger people might mistake findings and assume that criminal behaviour is predetermined and inescapable
- FURTHERMORE: you need to interpret findings with caution. should look at data holistically (other factors). However it is still good for risk assessing risk
21
Q
If you were evaluating the procedures, what would be a strength (use PET paragraph)
A
- P: Standardised procedures
-E: Done in a lab, standardised timings (30 seconds of CPT + PET scan done after 32 mins) and medication free participants (tested with urine sample 2 weeks prior). This meant they had control over extraneous variables, increasing validity + reliability - T: therefore if findings can be replicated and the reliability of Raine’s research can be checked for consistency, it makes for more valued and trusted research. It also means that validity can be considered, especially over time
-C: low ecological validity because they were on medication before the scan and the medication could’ve cause differences in the brain that made them commit the violent acts in the first place
22
Q
If you were evaluating the procedures, what would be a weakness (use PET paragraph)
A
- P: only murderers were studied
- E: the sample was 41 murderers (2 women 39 men, 6 schizophrenics)
- T: many violent crimes don’t involve murder, e.g. robbery. Therefore, conclusions are restricted to a very specific group of criminals
- C: Can’t be generalised to all criminals because not all criminals are murders.
23
Q
What are the alternative evidences
A
- Yang and Raine (2009)
- role of Genes (MAOA) supported by Tiihonen et al (2015)
- the principle of diathesis-stress (Jim Fallon)
24
Q
Outline what happened in Yang and Raine (2009)
A
- Yang and Raine conducted a meta-analysis of 43 imaging studies of both violent and antisocial behaviour
- they found reduced activity in the prefrontal cortex
- prefrontal cortex is responsible for decision making (last to develop)
- therefore reduced activity = take more risks
25
Outline the alternative evidence for Genes
- ‘Criminal genes’ - MAOA (monoamine oxidase A)
- MAOA regulates dopamine
- low MAOA = can cause aggressive behaviour
- Tiihonen et al (2015) analysed genes of 895 Finnish prisoners
- found an association between MAOA and in likelihood of committing a violent crime
26
Explain the principle of diathesis-stress
- Diathesis (genetic predisposition)
- Stress (triggers in environment, e.g. bad childhood - ‘maltreatment’)
- Positive experiences in childhood mean that criminal tendencies weren’t triggered, e.g. Jim Fallon
27
What are the 3 things we evaluate when talking about ethical issues of this experiment
- Lack of valid consent
- Possible risk of psychological harm
- Lack of right to withdraw
28
Explain the issue of lack of valid consent
1. No capacity to consent (as they were NGRIs)
2. It was coercive consent (lawyers suggest taking part to gain evidence for a reduced sentence = can’t really say no)
29
Explain the issue of possible risk of psychological harm
- the scan might’ve been uncomfortable
- the FDG injection could’ve hurt
- The CPT might’ve been too difficult and then embarrassed them
30
Explain the issue of lack of right to withdraw
- same kind of reasons for the lack of valid consent
—> no capacity
—> can’t really withdraw if lawyers get them to do it (coercive)
31
What are the social implications of this study
Social implications can be drawn such as
- identifying criminals from brain scans before they commit a crime
- should we sterilise those with criminal brains so they can’t reproduce?
- saying criminals are not responsible for their behaviour and presenting brain scans in court for a reduced sentence
- blaming biological factors and absolving society of any blame
