Criminal Psychology - Biological Explanation

Lombroso (1876) - ‘Criminal Evolution’

Theory of evolution explains why individuals turned to crime

Humans evolved to possess criminal features

Features:

• narrow sloping brow

• large ears

• defined jawline

• abnormalities such as extra toes or fingers

Evaluation of Lombroso

Limitations

• Deterministic

• Socially sensitive

• Not scientific

Strengths

• Nature

• Reductionist

Physiological explanations of criminality

• Lombroso

• Sheldon

• Jacobs

Sheldon (1942) - ‘The Criminal Body’

3 body types: Ectomorphs, Mesomorphs, endomorphs.

Mesomorphs most likely to be criminals as most common body type among inmate populations.

Sheldon (1942) - Other explanations for correlation between mesomorphs and criminality

1. Muscular build may find they can achieve things (rewards) more easily through force rather than hard work (operant conditioning)

2. Cannot escape the stigma around muscular builds and criminality regardless of their behaviour (self-fulfilling prophecy)

3. Nothing else to do in prison but build muscle

Evaluation of Sheldon

Limitations:

• Lacks external validity- little follow up

• Lacks population validity

Self fulfilling prophecy

Beliefs aboutnbothers can lead us to treat them in such a way that they subsequently become what we expect them to be

Non Physiological Explanations of Criminality

• Social learning theory

• Trzesniewksi- Self Esteem

• Self fulfilling prophecy

Trzesniewksi (2006) - Self Esteem

• Adolescents with low self esteem were more likely to engage in criminal activity compared to those with high self-esteem.

• Failed to reach self actualization due to not having access to self-esteem sources

Jahoda (1954) - Self Fulfilling Prophecy

In some cultures, children are assigned soul names (labels) depending on which day of the week they are born

Ashanti cultures:

• Monday boys- calm in nature

• Wednesday boys- aggressive and violent

• 7% of all violent offences were committed by monday boys

• 22% by Wednesday boys

Can also explain re-offending

Aim for Raine et al.

Study brain activity in murderers and non-murderers using PET scans to investigate differences in areas thought to be involved in violent behaviour

Sample for Raine et al.

• Matched pairs

• 41 murderers, (39m:2f). Mean age of 34.3 years. Pleaded not guilty by reason of insanity but convicted.

• Control/non-murderers. Matched for sex, age, diagnosis of schizophrenia for 6 murderers

Controls for Raine et al

• Matched characteristics: sex, age, diagnosis

• No participants took any medication for at least 2 weeks prior to testing

PET

Type of brain scan where the patient is injected with a radioactive ‘tracer’ which is used by the brain during respiration and can be traced to see brain activity levels in specific regions of the brain

CPT- Continuous Performance Task

Visual vigilance task which requires participant to pay constant attention. They are shown visual stimulus and asked to press a button whenever the pre-determined condition is met.

Design for Raine et al

Quasi experiment

Independent measures

Procedure for Raine et al

• P's brain scammed during a CPT. CPT increases activitiy in brain areas of interest in normal p's

• P's allowed to practise CPT

• 30 seconds before being injected with Fluorodeoxyglucose tracer for the PET scan, p's began full CPT session

• CPT continued for 32 minutes.

• PET images of 10 horizontal ‘slices’ throigh the brain were taken at 10mm intervals

Two techniques used to identify brain regions:

• Cortical peel technique

• Box technique

Scans analysed for activity levels in many different brain areas

Cortical peel technique

Used for lateral areas including superior frontal, middle frontal, inferior fortnal gyri and areas of temporal, parietal and occipital lobes

Box technique

Used for medical areas (inside the brain) including the superior frontal gyrus, anterior medial frontal gyrus, medial frontal gyrus and orbital gyrus.

Results for Raine et al

• Murderers had significantly less activity in the lateral (1.09 vs 1.12), medial (1.2 vs 1.25) and parietal (1.1 vs 1.15) prefrontal cortical areas and also in the corpus callosum (0.56 vs 0.68)

• They had abnormally asymmetrical activation in areas of the limbic system including the amygdala (less activation on the left but more on the right)

• Lower activation on the right in the temporal lobe/hippocampus and in the thalamus

Conclusions for Raine

Abmormal activity and their associations:

• Amygdala, hippocampus, thalamus -aggressive behaviour.

• Amygdala- lack of fear

• Prefrontal cortex- impulsiveness, lack of self control

• Amygdala, hippocampus, prefrontal cortex- problems with controlling and expressing emotions

Leads to increased risk of committing acts of extreme violence therefore crimes

• Also linked with problems with learning conditioned emotional responses and failure to learn from experiences

Effects on areas associated with learning could lower IQ, therefore lower chance of employment and higher risk of criminality

ABNORMAL BRAIN ACTIVITY INCREASES RISK OF COMMITTING SERIOUS CRIME