forensic psychology

• Offender profiling approaches


  • Top-down approach
  • Bottom-up approach
• Top-down approach


  • Uses evidence from the crime scene and other details to fit into pre-existing categories of organised or disorganised offender
• Organised offender


  • Crime tends to be planned
  • Victim is specifically targeted
  • Maintains high degree of control during crime
  • Leaves little evidence
  • Generally high in intelligence, socially and sexually competent, live with partner, have car, follow crimes in media
• Disorganised offender


  • Crime tends to be unplanned
  • Random selection of victim
  • Very little control during crime, impulsive
  • Body/evidence left at crime scene
  • Tend to have lower than average IQ, in unskilled work or unemployed, history of sexual dysfunction and failed relationships, live alone
• Top-down profile construction


  1. Data assimilation

  2. Crime scene classification

  3. Crime reconstruction

  4. Profile generation
• Bottom-up approach


  • Data-driven using statistical databases, grounded in psychological theory
• Investigative psychology


  • Matches crime scene details with statistical analysis of typical offender behaviour
  • Focuses on interpersonal coherence, time/place, forensic awareness
• Geographical profiling


  • Studies spatial behaviour to infer offender's home/operational base
  • Canter's circle theory - marauder vs commuter
• Monoamine oxidase A (MAOA) gene


  Gene that produces an enzyme that breaks down neurotransmitters like dopamine and noradrenaline, linked to aggression
• MAOA-L


  Low activity form of MAOA gene, results in less enzyme production and higher neurotransmitter levels, linked to aggression and offending behaviour
• Genetic transmission of criminal behaviour


  • Criminal behaviour runs in families and is transmitted genetically
  • Twin studies show higher concordance rates for identical twins vs non-identical twins
• Monozygotic (MZ) and dizygotic (DZ) twins

  MZ twins are identical, DZ twins are non-identical
• If MZ twins have higher concordance rates for offending behaviour than DZ twins

  Genetic factors are involved in offending behaviour
• Lange (1930) study


  • Investigated 13 MZ and 17 DZ twins where one twin had served time in prison
  • Found 77% concordance rate for MZ twins and 12% for DZ twins
  • Concluded genetic factors play a predominant part in offending behaviour
• Genetic approach to offending behaviour

  • Suggests offending behaviour has a genetic basis
  • Supported by twin studies showing higher concordance rates for MZ twins compared to DZ twins
• The gene for MAOA (monoamine oxidase A) is linked to aggression and offending behaviour
• Brunner et al. (1993) study


  • Investigated a Dutch family where several generations of men had a history of aggressive and violent acts
  • Found the men had a genetic condition (Brunner syndrome) resulting in lower intelligence and MAOA deficiency
  • Offers evidence that individuals can inherit genetic conditions that make them prone to offending behaviour
• Christiansen (1977) found concordance rates of 33% for MZ twins and 12% for DZ twins, suggesting offending may have a genetic component
• A problem with twin studies is that most twins are reared in the same environment, so concordance rates may be due to shared learning experiences rather than genetics
• Diathesis-stress model


  Suggests offending behaviour arises from the combination of genetic predisposition and environmental factors (e.g. dysfunctional upbringing, criminal role models)
• Caspi et al. (2002) study

  • Found low activity version of MAOA gene alone was not a significant predictor of aggression, but low MAOA gene plus maltreatment had a significant effect
• Genetic explanations are criticised as biologically deterministic, suggesting genes completely control behaviour
• Evidence suggests genetics alone cannot fully explain offending behaviour, as not everyone with a 'criminal gene' becomes an offender
• Neural explanations of offending behaviour

  • Focus on differences in brain structure and neurotransmitter levels
  • Suggest offending is linked to aggression and impaired impulse control
• Amygdala


  Part of the limbic system that processes emotional information, implicated in offending behaviour as it is involved in the stress response and aggressive impulses
• Prefrontal cortex


  Regulates impulse control and social interactions, damage has been linked to antisocial and offending behaviour
• Serotonin


  Regulates mood and impulse control, low levels could be linked to offending behaviour
• Noradrenaline


  Abnormally high levels have been associated with aggression, violence and criminality
• Raine et al. (2000) found reduced brain activity in areas like the prefrontal cortex and abnormalities in the limbic system in offenders compared to controls
• Strengths of neural explanations

  • Use of objective scientific methods like PET scans
  • Potential for practical applications like dietary interventions to alter neurotransmitter levels
• Neural explanations are reductionist, simplifying offending behaviour to biological factors and overlooking social/environmental factors
• Atavistic form


  Lombroso's theory that criminals have distinguishing physical features indicating they are 'genetic throwbacks' to a more primitive stage of evolution
• Lombroso's findings on physical features of different types of criminals

  • Murderers: beak-like nose, bloodshot eyes, curly hair
  • Sexual offenders: projecting ears, swollen lips
  • Fraudsters: thin, 'reedy' lips
• Strengths of Lombroso's approach


  • Used a scientific, evidence-based approach to study criminals
  • Raised the possibility of scientific study of the criminal mind
• Goring (1913) failed to replicate Lombroso's findings when comparing convicts and non-convicts
• Lombroso's theory was criticised as biologically deterministic and socially sensitive/racist
• Eysenck believed criminals have a personality type characterised by high extraversion, neuroticism and psychoticism
• Extraversion


  Extraverts are sociable, impulsive, expressive and risk-taking, and need more external stimulation
• Antisocial behaviour


  Behaviour that goes against social norms and expectations, often associated with criminal behaviour
• Even though it is a psychological theory of personality, Eysenck believed that each trait has a biological basis which is mainly innate and comes about through the type of nervous system we inherit