Raine et al (1997) Classic Study

Question 1

What did the aim investigate?

Answer 1

Differences in brain activity in NGRIs compared to a matched sample of non murderers using PET: specifically in prefrontal cortex, amygdala etc to see if brain disfunction predisposed people to violent behaviour

Question 2

Number of participants?

Answer 2

41(39 males and 2 females) charged with murder who had pleaded ‘not guilty by reasons of insanity’ and a control group of 41

Question 3

what were the control group matched on?

Answer 3

age and gender

Question 4

What were the participants screened for?

Answer 4

general health

Question 5

What were the participants told to do 2 weeks prior the experiment?

Answer 5

not take any medication

Question 6

What did participants do before being injected with a radioactive glucose tracer?

Answer 6

they completed a 10 minute practice test

Question 7

After being injected with the radioactive glucose tracer, participants completed a

Answer 7

continuous performance task for 32 minutes

Question 8

Why did participants complete a 32 minute long continuous performance task?

Answer 8

Because it increases the activity in the frontal lobes of ‘normal participants’

Question 9

What did the continuous performance task consist of?

Answer 9

A sequence of blurred numbers to focus on

Question 10

A PET scan was performed immediately after the CPT which indicated

Answer 10

the level of activity in different areas of the brain

Question 11

Murderers results for left medial prefrontal cortex

Answer 11

1.20

Question 12

Murderers results for right medial prefrontal cortex

Answer 12

1.17

Question 13

Non murderers results for left medial prefrontal cortex

Answer 13

1.25

Question 14

Non murderers results for right medial prefrontal cortex

Answer 14

1.22

Question 15

Murderers results for the left amygdala

Answer 15

0.94

Question 16

Murderers results for the right amygdala

Answer 16

0.88

Question 17

Non murderers results for the left amygdala

Answer 17

0.97

Question 18

Non murderers results for the right amygdala

Answer 18

0.83

Question 19

Murderers results for the right thalamus

Answer 19

1.15

Question 20

Non murderers results for the right thalamus

Answer 20

1.09

Question 21

Who had higher activity in the occiptial lobe?

Answer 21

Murderers

Question 22

Conclusions?

Answer 22

Murderers have different brain functions to non murderers, the findings support that there are biological causes, prefrontal deficits cause implusivity and loss of self control

Question 23

The hippocampus, amygdala and thalamus have all been related to

Answer 23

learning and it has been suggested that abnormal activity here could result in criminals being unable to modify their behaviour since they can’t learn from consequences

Question 24

PET scanning was used and such scans can be interpreted objectively by more than one researcher meaning the results

Answer 24

tend to be reliable, as the same results can be found by different people , giving inter rater reliability

Question 25

A large sample of 82 ppts which was the largest sample at the time using PET scans which means there were

Answer 25

sufficient people in each group for conclusions to be drawn and generalisation might have been possible to other murderers pleading not guilty by reason of insanity

Question 26

The results of the study have application to real life as they are able to provide the possibility that there may be biological factors in the murderer’s behaviour, although

Answer 26

this cannot be shown by this research, it provides the basis for further research to investigate if it is the differences in brain function

Question 27

Reliability is high as there were many controls like

Answer 27

> everyone did the 10min practice
the specific time gap of 32 mins between the injection and the PET
PET is objective

Question 28

The researchers controlled potential factors that could have impacted the results since they

Answer 28

matched the groups and areas that were not matched were tested so comparisons could be drawn fairly giving internal validity

Question 29

The findings describe the brain differences but do not explain them, it could be they were present from birth but it could be from the environment which

Answer 29

would suggest they are not caused biologically even if they are biological factors

Question 30

The findings do not explain if the murderers are

Answer 30

responsible for their behaviour due to brain differences

Question 31

Internal validity may be limited as the researchers commented on the fact that the PET scans were not clear which may have

Answer 31

affected their interpretation of images, meaning that mistakes could have been made due to subjectivity, meaning the results may not be accurate

Question 32

The results can only be generalised to murderers pleading not guilty by reasons of insanity therefore the findings cannot be said to be true pf all violent behaviour as

Answer 32

they were not included in the sample, even though violence was being studied, making the sample not representative of the target population.

Question 33

Generalisability is also limited as non violent criminals in the control group so

Answer 33

we cannot see if the same brain differences would be found in all criminals of different types