Forensic Psychology
Lecture One
Theories of Crime
What is a theory?
Any description of an observed aspect of the world that may consist of a collection of
interrelated laws or a systematic set of ideas (Kukla, 2001)
Theories arise from observing a developing problem and inferring existence of an underlying
mechanism
They give rise to plausible hypotheses
Development of models can help to elaborate on nature of underlying mechanisms
Theory appraisal – predictive accuracy and scope; can it account for existing findings?
Internal coherence – can it be falsified? It should be testable and able to be
challenged/disproved
External consistency – is it consistent with what already exists in literature or is it an
anomaly?
Unifying power – can it unify different aspects of research?
Fertility/heuristic value – can it lead to new predictions?
Simplicity – does it make any special assumptions or are the principles basic?
Explanatory depth – can it describe and explain deep underlying mechanisms?
Psychological theories of crime
Psychological theories explain common behaviour traits in criminals/why these traits exist in
some people but not others
Theory: Crime is a product of attachment insecurity
Bowlby – 44 Thieves study (1951)
Argues that maternal deprivation can lead to a ‘cold, affectionless character’ associated with
criminal behaviour
In his study found that almost 40% of the juvenile criminals had experienced separation of
over 6 months, whereas only 2 of the control group had
1/3 of juvenile thieves were described as having affectionless psychopathy compared to 0 of
the control
However, this was a small sample based on retrospective memories and there are many
confounding variables e.g. could be the fact they were raised in an institution that caused
delinquency, not the disruption of attachment directly
Other studies to support the theory include the Newcastle Thousand Family birth cohort
study (Kolvin, 1988) – risk of conviction up to age 32 doubled for boys who experience
maternal deprivation or privation
Also the Cambridge study (Farrington et al, 2009) – 60% of boys separated from parent by
their 10th birthday had a conviction by age 50, compared to 36% with no separation
Juby and Farrington found that this depends on the type of disruption, for example a
sequence of stressors after separation could cause delinquency, not just the separation itself
Attachment types and criminality: studies have found that the avoidant attachment type is
common in offenders
, E.g. Allen et al (1996) found the avoidant type was linked with hard drug use and criminality
in hospitalised adolescents
Rosenstein & Horowitz (1996) found associated diagnoses of ASPD and self-reported
antisocial traits with avoidant types
Frodi et al (2001) – avoidant most characteristic among psychopathic offenders
Ward et al argued that different attachment styles lead to different styles of offending, e.g.
rapists and violent offenders more likely to be avoidant/dismissive type whereas
paedophiles more likely to show preoccupied/fearful style, characterised by a need for
intimacy and fear of abandonment; children may fulfil social and sexual needs that they
cannot achieve with adult relationships
Evaluation of attachment theories:
They provide context for understanding the link between parent child relationships and
future behaviours, as attachment can influence processes, including emotional regulation,
that are important moderators of antisocial behaviour
However – it may be unfair to place such strong emphasis and blame on mothers of
criminals, takes away blame from the criminal (free will?)
Theory: Crime is learned
Based on principles of Skinners’ operant conditioning
Jeffrey (1965) suggested that criminal behaviour develops through operant conditioning as
acts may be reinforced (e.g. stealing = money gain) and the aversive consequences may not
be strong enough to act as a deferent
If this is true – then it should be possible to recondition offenders to stop offending
One case study demonstrates this successfully: Marshall (2006) treatment programme for
‘Bill’ a 38 year old sex offender (offences against children)
Used olfactory aversive conditioning (bad smells paired with sexual images of children) and
masturbatory reconditioning (conditioning to be aroused by more socially acceptable
images through CBT)
This was successful – he never reoffended and had a normal relationship with an adult
female, however, this is only one case study and may not be representative
Social learning theory (Bandura) – learning through modelling behaviour observed
Attention – Retention – Reproduction – Motivation
Haapasalo & Pokela, 1999, found harsh parenting could be predictive of later offending
Newson & Newson (1989) found parents’ use of physical punishment at ages 7 and 11
predicts later antisocial deviance
Robins, 1979, longitudinal study found delinquency predicted by poor parental supervision,
harsh discipline and rejecting attitude
Farrington Cambridge study (2005) – family factors found to be predictive of later antisocial
behaviour e.g. poor parental supervision at 8 predicted antisocial deviance at age 48 and
harsh/erratic parenting predictive of psychopathic traits
Evaluation – suggests how early experiences can have long lasting effects, most observable
behaviours do have a relationship to learning, provides detailed account of how
environment influences learning, implications for treatment
However – doesn’t account for biological factors, unfair to blame childhood environment,
not all abused go on to abuse
Integrated cognitive antisocial potential (ICAP) theory: based on findings of Cambridge study
Integrates a range of risk factors for offending and a range of other theories e.g. strain,
learning (focuses on lower class males)
, What cognitive processes lead to someone with the potential to display antisocial behaviour
to actually committing a crime?
We all have the potential to be antisocial – whether this potential is released depends on
thoughts of opportunities and victims
Long term antisocial potential: more impulsive, poorer background, socialisation, sensation
seeking, lower intelligence, negative life events – offenders on a continuum of low to high,
those with more issues will be more criminally versatile (wider range of criminal activity)
Short term antisocial potential: situational factors e.g. short term anger, being bored,
alcohol misuse, marriage – can develop in the long term if behaviour is reinforced
Biological Theories of crime
Focuses on how biological factors may cause an individual to commit crime e.g.
neurotransmitters, brain structure, genetics etc. Founded from early psychologists e.g. Franz
Josef Gall (phrenology) and Lombroso (anthropological criminology). Can be useful to help
advance our knowledge of crime and violence beyond environmental factors and result in
new methods of assessment/treatment as well as scientific methods of studying criminals.
Theory: Crime is inherited
Concordance rates of criminality in MZ and DZ twins can help us determine heritability of
crime
Blonigen et al (2003) – sampled 353 adult twins and assessed them with the Psychopathic
Personality Inventory (PPI) found a correlation of .46 for MZ and .26 for DZ suggesting some
genetic contribution
Genetic influences on aggression – Plomin et al (1990) reviewed 11 twin studies and showed
moderate evidence for heritability (MZ = .32 and DZ = .14)
Miles and Carey (1997) – meta-analysis suggesting genetics and shared environment account
for up to 50% variability in aggression
Baker suggested that genetics may influence different types of aggression e.g. reactive (hot)
vs instrumental (cold)
Found that reactive aggression heritability was 38% but instrumental 50% - only in boys, no
effect for girls
Reactive aggression is more likely to be triggered by the environment
However there are issues with twin studies e.g. MZ more likely to have similar environment
than DZ – can study those reared apart but rare to find
Grove et al (1990) interviewed 32 sets of MZ twins reared apart and obtained scores for
antisocial behaviours
Found heritability of childhood ASB to be 41% and adult ASB 28%
Monoamine Oxidase A (MAOA) – The Warrior Gene: males with defective MAOA gene
showed impulsive violence, mood swings, aggression and low IQ (high levels of dopamine
and serotonin as MAOA is not present to break them down)
High dopamine and low serotonin levels have been associated with aggression
XYY chromosomes – in 1961 it was discovered that some males may have an extra Y
chromosome due to mutation (1/1000 of the population)
One paper found that mentally disordered male forensic patients were 40 times more likely
to have this defect (4% of the population in institution)
Theory: Crime reflects abnormal neurochemistry
, Oxytocin (OT) and Arginine Vasopressin (AVP) thought to be associated with forming
attachments and relationships, those with no adequate attachments have lower levels e.g.
Romanian orhpans
OT associated with increased trust, generosity and interpretation of emotional responses
Those with attachment issues could have biological defects that makes them more likely to
be antisocial?
However there is contradicting evidence e.g. Mitchell et al (2013) found increased urinary
OT in sexual and violent offenders/diagnosed psychopaths – perhaps OT plays role in both
antisocial and prosocial behaviour
De Wall et al (2014) found intranasal OT to increase intimate partner violence when
provoked – but only observed among high trait aggressiveness pp’s – could reflect
evolutionary ways to maintain relationships
Perhaps an interactive effect with OT and personality traits to predict partner violence
Nutrition – longitudinal studies have found that malnutrition in infancy is associated with
aggressive behaviour and attentional deficits in adulthood
Liu and Raine (2006) found children with protein, iron and zinc deficiencies at age 3 had
significantly more aggressive and hyperactive behaviour at the age of 8 and more antisocial
behaviour at 11 and more conduct disorder at 17
Gesch et al (2002) studied 231 adult prisoners in a double blind setting where they were
given vitamins or placebos
After taking supplements for two weeks average 35.1% reduction in offences, no change in
control
Prenatal alcohol exposure – can lead to foetal alcohol syndrome with behavioural
disabilities/higher likelihood of abnormal sexual behaviour and committing crimes
Lecture 2
Eyewitness Memory
System variables – variables effecting eye witness testimony that are directly under the
control of criminal justice system e.g. interviewing technique, time between crime and
questioning etc.
Estimator variables – variables effecting eye witness testimony that are outside of the
control of CJS e.g. eyewitness characteristics, own age effect, weapon focus etc.
Attention
Change blindness – failure to notice changes that occur when continuously monitoring a
visual scene
Experimentally demonstrated with eyewitness task (Davies and Hine, 2007)
Weapon focus effect – presence of a weapon has detrimental impact on pp’s memory
Possibly because arousal narrow attentional beam or the cognitive demands inherent in
processing an unusual object that is incongruent with the schema representing the visual
scene (unusual item hypothesis)
Meta-analysis by 2013 indicated an effect of weapon presence that was significantly
influenced by retention interval, the focus effect decreases over time
Encoding
Stress and memory -Yerkes-Dodson Law
Stress may enhance memory for central details and worsen for peripheral
Lecture One
Theories of Crime
What is a theory?
Any description of an observed aspect of the world that may consist of a collection of
interrelated laws or a systematic set of ideas (Kukla, 2001)
Theories arise from observing a developing problem and inferring existence of an underlying
mechanism
They give rise to plausible hypotheses
Development of models can help to elaborate on nature of underlying mechanisms
Theory appraisal – predictive accuracy and scope; can it account for existing findings?
Internal coherence – can it be falsified? It should be testable and able to be
challenged/disproved
External consistency – is it consistent with what already exists in literature or is it an
anomaly?
Unifying power – can it unify different aspects of research?
Fertility/heuristic value – can it lead to new predictions?
Simplicity – does it make any special assumptions or are the principles basic?
Explanatory depth – can it describe and explain deep underlying mechanisms?
Psychological theories of crime
Psychological theories explain common behaviour traits in criminals/why these traits exist in
some people but not others
Theory: Crime is a product of attachment insecurity
Bowlby – 44 Thieves study (1951)
Argues that maternal deprivation can lead to a ‘cold, affectionless character’ associated with
criminal behaviour
In his study found that almost 40% of the juvenile criminals had experienced separation of
over 6 months, whereas only 2 of the control group had
1/3 of juvenile thieves were described as having affectionless psychopathy compared to 0 of
the control
However, this was a small sample based on retrospective memories and there are many
confounding variables e.g. could be the fact they were raised in an institution that caused
delinquency, not the disruption of attachment directly
Other studies to support the theory include the Newcastle Thousand Family birth cohort
study (Kolvin, 1988) – risk of conviction up to age 32 doubled for boys who experience
maternal deprivation or privation
Also the Cambridge study (Farrington et al, 2009) – 60% of boys separated from parent by
their 10th birthday had a conviction by age 50, compared to 36% with no separation
Juby and Farrington found that this depends on the type of disruption, for example a
sequence of stressors after separation could cause delinquency, not just the separation itself
Attachment types and criminality: studies have found that the avoidant attachment type is
common in offenders
, E.g. Allen et al (1996) found the avoidant type was linked with hard drug use and criminality
in hospitalised adolescents
Rosenstein & Horowitz (1996) found associated diagnoses of ASPD and self-reported
antisocial traits with avoidant types
Frodi et al (2001) – avoidant most characteristic among psychopathic offenders
Ward et al argued that different attachment styles lead to different styles of offending, e.g.
rapists and violent offenders more likely to be avoidant/dismissive type whereas
paedophiles more likely to show preoccupied/fearful style, characterised by a need for
intimacy and fear of abandonment; children may fulfil social and sexual needs that they
cannot achieve with adult relationships
Evaluation of attachment theories:
They provide context for understanding the link between parent child relationships and
future behaviours, as attachment can influence processes, including emotional regulation,
that are important moderators of antisocial behaviour
However – it may be unfair to place such strong emphasis and blame on mothers of
criminals, takes away blame from the criminal (free will?)
Theory: Crime is learned
Based on principles of Skinners’ operant conditioning
Jeffrey (1965) suggested that criminal behaviour develops through operant conditioning as
acts may be reinforced (e.g. stealing = money gain) and the aversive consequences may not
be strong enough to act as a deferent
If this is true – then it should be possible to recondition offenders to stop offending
One case study demonstrates this successfully: Marshall (2006) treatment programme for
‘Bill’ a 38 year old sex offender (offences against children)
Used olfactory aversive conditioning (bad smells paired with sexual images of children) and
masturbatory reconditioning (conditioning to be aroused by more socially acceptable
images through CBT)
This was successful – he never reoffended and had a normal relationship with an adult
female, however, this is only one case study and may not be representative
Social learning theory (Bandura) – learning through modelling behaviour observed
Attention – Retention – Reproduction – Motivation
Haapasalo & Pokela, 1999, found harsh parenting could be predictive of later offending
Newson & Newson (1989) found parents’ use of physical punishment at ages 7 and 11
predicts later antisocial deviance
Robins, 1979, longitudinal study found delinquency predicted by poor parental supervision,
harsh discipline and rejecting attitude
Farrington Cambridge study (2005) – family factors found to be predictive of later antisocial
behaviour e.g. poor parental supervision at 8 predicted antisocial deviance at age 48 and
harsh/erratic parenting predictive of psychopathic traits
Evaluation – suggests how early experiences can have long lasting effects, most observable
behaviours do have a relationship to learning, provides detailed account of how
environment influences learning, implications for treatment
However – doesn’t account for biological factors, unfair to blame childhood environment,
not all abused go on to abuse
Integrated cognitive antisocial potential (ICAP) theory: based on findings of Cambridge study
Integrates a range of risk factors for offending and a range of other theories e.g. strain,
learning (focuses on lower class males)
, What cognitive processes lead to someone with the potential to display antisocial behaviour
to actually committing a crime?
We all have the potential to be antisocial – whether this potential is released depends on
thoughts of opportunities and victims
Long term antisocial potential: more impulsive, poorer background, socialisation, sensation
seeking, lower intelligence, negative life events – offenders on a continuum of low to high,
those with more issues will be more criminally versatile (wider range of criminal activity)
Short term antisocial potential: situational factors e.g. short term anger, being bored,
alcohol misuse, marriage – can develop in the long term if behaviour is reinforced
Biological Theories of crime
Focuses on how biological factors may cause an individual to commit crime e.g.
neurotransmitters, brain structure, genetics etc. Founded from early psychologists e.g. Franz
Josef Gall (phrenology) and Lombroso (anthropological criminology). Can be useful to help
advance our knowledge of crime and violence beyond environmental factors and result in
new methods of assessment/treatment as well as scientific methods of studying criminals.
Theory: Crime is inherited
Concordance rates of criminality in MZ and DZ twins can help us determine heritability of
crime
Blonigen et al (2003) – sampled 353 adult twins and assessed them with the Psychopathic
Personality Inventory (PPI) found a correlation of .46 for MZ and .26 for DZ suggesting some
genetic contribution
Genetic influences on aggression – Plomin et al (1990) reviewed 11 twin studies and showed
moderate evidence for heritability (MZ = .32 and DZ = .14)
Miles and Carey (1997) – meta-analysis suggesting genetics and shared environment account
for up to 50% variability in aggression
Baker suggested that genetics may influence different types of aggression e.g. reactive (hot)
vs instrumental (cold)
Found that reactive aggression heritability was 38% but instrumental 50% - only in boys, no
effect for girls
Reactive aggression is more likely to be triggered by the environment
However there are issues with twin studies e.g. MZ more likely to have similar environment
than DZ – can study those reared apart but rare to find
Grove et al (1990) interviewed 32 sets of MZ twins reared apart and obtained scores for
antisocial behaviours
Found heritability of childhood ASB to be 41% and adult ASB 28%
Monoamine Oxidase A (MAOA) – The Warrior Gene: males with defective MAOA gene
showed impulsive violence, mood swings, aggression and low IQ (high levels of dopamine
and serotonin as MAOA is not present to break them down)
High dopamine and low serotonin levels have been associated with aggression
XYY chromosomes – in 1961 it was discovered that some males may have an extra Y
chromosome due to mutation (1/1000 of the population)
One paper found that mentally disordered male forensic patients were 40 times more likely
to have this defect (4% of the population in institution)
Theory: Crime reflects abnormal neurochemistry
, Oxytocin (OT) and Arginine Vasopressin (AVP) thought to be associated with forming
attachments and relationships, those with no adequate attachments have lower levels e.g.
Romanian orhpans
OT associated with increased trust, generosity and interpretation of emotional responses
Those with attachment issues could have biological defects that makes them more likely to
be antisocial?
However there is contradicting evidence e.g. Mitchell et al (2013) found increased urinary
OT in sexual and violent offenders/diagnosed psychopaths – perhaps OT plays role in both
antisocial and prosocial behaviour
De Wall et al (2014) found intranasal OT to increase intimate partner violence when
provoked – but only observed among high trait aggressiveness pp’s – could reflect
evolutionary ways to maintain relationships
Perhaps an interactive effect with OT and personality traits to predict partner violence
Nutrition – longitudinal studies have found that malnutrition in infancy is associated with
aggressive behaviour and attentional deficits in adulthood
Liu and Raine (2006) found children with protein, iron and zinc deficiencies at age 3 had
significantly more aggressive and hyperactive behaviour at the age of 8 and more antisocial
behaviour at 11 and more conduct disorder at 17
Gesch et al (2002) studied 231 adult prisoners in a double blind setting where they were
given vitamins or placebos
After taking supplements for two weeks average 35.1% reduction in offences, no change in
control
Prenatal alcohol exposure – can lead to foetal alcohol syndrome with behavioural
disabilities/higher likelihood of abnormal sexual behaviour and committing crimes
Lecture 2
Eyewitness Memory
System variables – variables effecting eye witness testimony that are directly under the
control of criminal justice system e.g. interviewing technique, time between crime and
questioning etc.
Estimator variables – variables effecting eye witness testimony that are outside of the
control of CJS e.g. eyewitness characteristics, own age effect, weapon focus etc.
Attention
Change blindness – failure to notice changes that occur when continuously monitoring a
visual scene
Experimentally demonstrated with eyewitness task (Davies and Hine, 2007)
Weapon focus effect – presence of a weapon has detrimental impact on pp’s memory
Possibly because arousal narrow attentional beam or the cognitive demands inherent in
processing an unusual object that is incongruent with the schema representing the visual
scene (unusual item hypothesis)
Meta-analysis by 2013 indicated an effect of weapon presence that was significantly
influenced by retention interval, the focus effect decreases over time
Encoding
Stress and memory -Yerkes-Dodson Law
Stress may enhance memory for central details and worsen for peripheral
