A2 - Turning to Crime - Biology - Brain Dysfunction Flashcards
What is the context for brain dysfunction?
The incident of Phineas Gage
What happened to Phineas Gage?
- He suffered brain damage when a bolt shot through his eye, cheek and brain.
- His personality went from quiet and sober to drunk and violent
- Damage to the prefrontal cortex is believed to increase aggression
What does damage to cerebral (prefrontal cortex; hippocampus; amygdala and corpus callosum) do?
Prefrontal cortex damage > impulsivity and loss of control
Hippocampus damage > associated with a lack of inhibition of aggression
Amygdala damage > reduced activity associated with fearlessness
Corpus callosum damage > poor transfer of information between hemispheres > inability to grasp the long-term implications
What did Raine et al do?
They conducted a study to compare brain activity in murderers and non-murderers, to plead not guilty by reasons of insanity (NGRI)
What experimental design was used?
Matched pair designs.
What was the experimental group made up of?
41 (39 males and 2 females) participants facing a murder or manslaughter charge, some have schizophrenia, brain damage, chronic drug abuse, etc.
What was the control group made up of?
Participants matched for age and gender.
What did participants do?
- They didn’t take medication for 2 weeks
- They were injected with a radioactive glucose tracer, they then did a continuous performance task
What did they find?
- Less activity in prefrontal cortex and corpus callosum
- Asymmetry of activity in: amygdala; thalamus and hippocampus (more activity on left side)
- Increased activity in the cerebellum
What are the conclusions of this study?
Criminals have different brain functioning to non-delinquents.
- murderers pleading NGRI had different brain functioning to ‘normal’ people
- murders have different brain functions to psychiatric patients
- brain differences may predispose and individual to violent behaviour
How is the study reliable?
High control, use of matched pair designs and participants weren’t on medication
How might the study be unethical?
Patients were told to go off their meds for the sake of the experiment
How is the study reductionist?
It focuses on physiological factors, not taking into account social and cognitive factors.
How might the study be low in generalizability?
The experimental group is made up of murderers, so we can’t generalise findings to other crimes, especially non-violent ones.
How might the study lack validity?
CPT has no bearing on violent tasks or the decision to be violent, as it may not be measuring the correct level of brain dysfunction in violent behaviour
