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
  • Tends to be high in intelligence, socially/sexually competent, lives with partner, has car, follows crimes in media
• Disorganised offender


  • Crime tends to be unplanned
  • Random selection of victim
  • Has very little control during crime, impulsive
  • Body/evidence left at crime scene
  • Tends to have lower than average IQ, in unskilled work/unemployed, history of sexual dysfunction, lives alone
• Top-down profile construction


  1. Data assimilation

  2. Crime scene classification

  3. Crime reconstruction

  4. Profile generation
• Bottom-up approach


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


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


  • Studies spatial behaviour and location of crime scenes to infer offender's home/base
• 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
• Genetic transmission of criminal behaviour


  • Criminal behaviour runs in families, offenders inherit genes that predispose them to crime
  • Twin studies show higher concordance rates for identical twins vs non-identical twins
• Monozygotic (MZ) and dizygotic (DZ) twins

  MZ twins are genetically identical, DZ twins share around 50% of their genes
• If MZ twins have a higher concordance rate for offending behaviour than DZ twins, it is assumed that genetic factors are involved
• 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 must play a predominant part in offending behaviour
• Genetic approach to offending behaviour

  • Research support for the role of the MAOA gene in offending behaviour
  • Research support from twin studies showing higher concordance rates for MZ vs DZ twins
• Diathesis-stress model


  Tendency towards criminal behaviour may come from combination of genetic predisposition and environmental factors (e.g. dysfunctional upbringing, criminal role models)
• Genetic explanations are deterministic - they suggest genes control behaviour and it is outside of an individual's control
• Neural explanations for offending behaviour

  • Differences in brain structure (e.g. amygdala, prefrontal cortex)
  • Irregularities in neurotransmitter levels (e.g. serotonin, noradrenaline)
• Raine et al. (2000) study


  • Used PET scans to find reduced brain activity in prefrontal cortex, corpus callosum, and abnormalities in limbic system of offenders compared to controls
• Neural explanations allow for objective, scientific investigation of offending behaviour
• Neural explanations have practical applications, e.g. using diet/medication to alter neurotransmitter levels and reduce aggression
• Neural explanations are reductionist, simplifying complex behaviour to biological 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
• Lombroso's atavistic form theory was criticised for lack of adequate controls and being socially sensitive/racist
• Lombroso's theory was deterministic, suggesting criminals cannot be blamed for their actions due to their innate, inherited physiology
• Antisocial behaviour


  Behaviour that goes against social norms and expectations, often associated with criminal behaviour
• Biological basis of personality traits

  Innate and comes about through the type of nervous system we inherit
• Eysenck Personality Questionnaire (EPQ)


  Psychological test to assess an individual's personality
• Extraversion


  • Sociable, impulsive, expressive and risk taking
  • People with high levels are under-aroused in their central and autonomic nervous system and therefore need more external stimulation compared to an introvert
• Extraversion and criminal personality

  Extraverts seek external stimulation to increase their cortisol arousal, often taking risks and engaging in dangerous thrill-seeking behaviour
• Neuroticism


  • Characterised by nervousness and obsessiveness
  • Have an autonomic nervous system that responds quickly to stress
• Neuroticism and criminal personality

  Neurotics are prone to over react to situations of threat which could explain criminal activity especially in an emotionally charged situation
• Psychoticism


  • Characterised by egocentric, cold and aggressive behaviour
  • Lack empathy as they are not concerned about the welfare of other people
  • Related to high levels of testosterone
• Psychoticism and criminal personality

  Psychotics can be easily linked to criminality as this type is characterised as lacking in empathy, unemotional and prone to aggression
• Eysenck provides evidence to support his theory of the criminal personality by comparing prisoners' scores on the EPQ with controls
• Farrington et al. reviewed several studies and reported that offenders tended to score high on Psychoticism measures, but not for Extroversion and Neuroticism
• There is very little evidence of consistent differences in EEG measures between extraverts and introverts, which casts doubt on the biological basis of Eysenck's theory
• The link between personality traits and criminal behaviour is unclear
• The idea that all offending behaviour can be explained by Eysenck's three personality dimensions can be heavily criticised