What is criminal psychology?

Criminal psychology is an interdisciplinary field that combines principles from psychology, criminology, and criminal justice. It focuses on understanding offenders and their behaviour to enhance crime investigations, such as through offender profiling.

This area explores various processes within the criminal justice system, including identifying suspects, making judgements about guilt, and developing treatment programmes to rehabilitate offenders. These programmes aim to reduce recidivism. They can be implemented in community settings or prisons.

Psychological research has also been applied to improve the accuracy of eyewitness testimony. Additionally, it examines courtroom procedures and has informed police interview techniques, drawing from cognitive psychology.

Biological explanations of crime: brain injury

Institute of Child Health study (2000)

• Aim - This research examined how damage to specific brain areas can lead to long-term behavioural issues.
• Method - Researchers analysed cases of two young boys who suffered accidental damage to the ventral region of the frontal lobes, an area involved in inhibiting impulses and promoting appropriate behaviour.
• Results - The boys displayed inability to control frustration or anger, poor monitoring of violent behaviour, lack of insight into consequences, and no concern for others.
• Conclusions - Damage to this brain region can cause serious antisocial tendencies, raising possibilities for using brain scans to predict behavioural problems after injuries.

Williams et al. study (2012)

• Aim - This more recent research explored the prevalence of brain injuries among offenders.
• Participants - Young adult offenders compared to the general population.
• Results - About 60% of young offenders reported brain injuries, three to six times higher than in the general population. These injuries affected temper control, social judgement, and impulse regulation, contributing to criminality.
• Conclusions - Brain injuries are more common in offenders, especially in developing brains, leading to mood and behavioural issues that hinder social adjustment.

Biological explanations of crime: the amygdala

Another biological factor involves the amygdala. Problems with the amygdala can lead to excessive aggression or lack of fear response, potentially contributing to criminal behaviour.

Damage to the amygdala might occur from strokes, tumours, or developmental issues. In overtly aggressive responses, it is thought that the amygdala misinterprets information from the senses and/or cortex, responding incorrectly with overly aggressive behaviour.

Key effects of amygdala dysfunction

• Overly aggressive responses - The amygdala may misinterpret information from the senses and/or cortex, responding incorrectly with overly aggressive behaviour. Stimulation studies on animals and humans show that activating specific amygdala areas provokes extreme aggression.
• Lack of fear response - Damage in other areas can result in no fear at all, as seen in rats with removed amygdalas that repeatedly approach danger without hesitation.
• Interaction with other brain regions - The amygdala connects to the prefrontal cortex, which helps inhibit negative emotions and aggression. A weakened connection can reduce control over aggressive impulses.

Genetic explanations of crime: XYY syndrome

XYY syndrome is a genetic condition where males have an extra Y chromosome, resulting in a 47-chromosome structure (XYY) instead of the typical 46 (XY for males or XX for females). This extra chromosome is present in some but not all cells.

Early research in the mid-20th century linked XYY syndrome to violence, suggesting these males were ten times more likely to be in criminal populations than XY males. However, further studies showed no strong evidence of increased violent tendencies.

Key points about XYY syndrome and crime

• Prevalence and traits - XYY males are rare, but they do not exhibit particularly aggressive behaviour beyond what is seen in the general population.
• Genetic vs. environmental factors - While aggression may run in families, indicating a possible genetic component, complex behaviours like violence are hard to attribute solely to genes, as environment plays a significant role.
• Limitations of the explanation - The rarity of XYY syndrome means it cannot account for the widespread occurrence of violent crime globally.

Personality explanations of crime: Eysenck's theory

Hans Eysenck proposed that personality can be measured along three dimensions, influencing how people respond to social norms and consequences.

Eysenck developed the Eysenck Personality Questionnaire (EPQ), a psychometric test that assesses individuals on these dimensions: extraversion-introversion (E), neuroticism-emotional stability (N), and psychoticism (P).

The three personality dimensions and their links to crime

• Extraversion (E) - Eysenck linked high E scores to difficulty in conditioning, meaning they do not easily learn from negative experiences or develop a strong conscience. This is due to under-arousal in the ascending reticular activating system (ARAS), a brain structure involved in alertness, leading extraverts to engage in risk-seeking or antisocial activities.
• Neuroticism (N) - Neurotic individuals are emotionally unstable and impulsive. High N scores relate to overactivity in the limbic system, which handles emotional responses, making it hard to inhibit behaviour. This can result in reactive crimes triggered by emotional events or habitual offending.
• Psychoticism (P) - High P scorers are insensitive, uncaring, and lack guilt or empathy. They may commit crimes easily without remorse, as they do not consider the impact on others.

E and N traits are normally distributed in the population, while P is skewed. Individuals with high scores across all three (high E, N, and P) are thought to be at greater risk of violent crime.