Aggression: Raine - Description

Question 1

Overview

Answer 1

Brain abnormalities in murderers indicated by PET scans

Question 2

Aim

Answer 2

To show that the brains of murderers who pleaded not guilty by reason of insanity (NGRI) were different from the brains of non-murderers.

Question 3

What did Raine specifically hypothesise?

Answer 3

Specifically, Raine hypothesised that seriously violent individuals would have relatively localised brain dysfunction in areas such as the pre-frontal cortex, amygdala and thalamus; areas linked to violence.

Question 4

Participants

Answer 4

» 41 murderers pleading NGRI (39 male, 2 female)

» control group matched on age and sex

» Ps had issues including history of brain damage, schizophrenia

» matched control group contained 6 schizophrenics

Question 5

Experimental conditions

Answer 5

» offenders were kept medicine free for 2 weeks

» test were done to confirm being left-handed/right-handed had no effect on behaviour

Question 6

Materials

Answer 6

» thermoplastic head holder

» PET scanner to image brain functioning

» FDG, a tracer injected to trace brain metabolism (it attaches itself to glucose being used in the brain and both can be picked up because FDG is radioactive)

» continuous performance task (CPT) to make frontal lobes work especially hard - spotting targets on a screen and pressing a button to indicate recognition of the target (32 mins)

Question 7

Procedure

Answer 7

1. 10 minutes before injection - practice trials on CPT
2. 30 seconds before injection - real task began (so that initial task novelty wouldn’t be recorded)
3. Ps monitored for 32 minutes after the injection and scanned using the PET scanner

Question 8

Results

Answer 8

» no significant difference in task performance between the two groups

» evidence of a significant difference in brain metabolism of glucose in various areas

–> preliminary (but not complete) evidence that murderers pleading NGRI have different brain functions