ac 2.1 biological theories Flashcards
what are biological theories?
Criminals are born biologically different causing criminality
What are the 4 types of biological theories?
Physiological, Genetic, Brain abnormality, biochemical.
what are physiological theories?
Criminals physical features are different to non criminals.
who are the 2 theorists for physiological theories?
Cesare Lombroso, William Sheldon
Key idea of lombrosos theory
Criminal features are different to non criminals
How is a ‘born criminal’ recognised?
Through their atavistic features.
What is atavism?
A throwback to primitive (presocial) stages of life.
Name at least 4 atavistic features
Large jaw
high cheekbones
long arms
prominant eyebrow arches
acute eyesight
large eye sockets
What was lombrosos study?
Studied features of 3839 alive criminals and 383 dead ones.
What percentage of criminal acts can be accounted for by atavistic features?
40%
Lombroso strengths
-First person to study crime scientifically
-helps focus on prevention rather than punishment
-led to beginning of criminal profiling
Lombroso limitations
-no control group
-Not everyone with atavistic features are criminal and vice versa
-assumes that people with atavistic features cant escape destiny
Key idea of Sheldon’s theory
Somatotype is linked to criminality
Whats an ectomorph?
Thin, fragile, self concious, emotionally restrained
whats an endomorph?
fat, soft, sociable, relaxed
Whats a mesomorph?
Hard, muscular, impulsive, adventurous
What was sheldons study?
studied pictures of college students and delinquents and rated their resemblance to mesomorphy on scale of 1-7. Delinquents higher average of mesomorph.
Strengths of sheldons study
-other studies replicate link between body type and criminality
-good sized sample and control group
Limitations of sheldons study
-mesomorphs more likely to be labelled as criminals
-body type can be built over time- nobody born mesomorph
-mesomorphs can be pressured into illegal acts
What are genetic theories?
Theories suggesting criminality is a result of genes inherited from parents
What’re the three theories?
jacobs xyy, twin studies, adoption studies
What do osborne and west say about sons?
sons with criminal fathers much more likely to become criminals too
What’re the 2 types of twins?
Monozygotic MZ- identical
Dyzigotic DZ- unidentical/ fraternal
what percentage of genes do MZ and DZ twins share?
MZ- 100%
DZ 50%
What is the key idea of twin studies?
If cause of criminality is genetic, MZ twins should have same criminality as they share 100% of genes.
What study did christiansen carry out?
Studied 3586 twin pairs in Denmark to find concordance rates
What did christiansens study show?
MZ- 52% concordance rate
DZ- 22% concordance rate
What is the key idea of adoption studies?
If criminality is genetic, adoptees will match criminality of biological parents more than adoptive
what is environmental explanation
Criminality result of surroundings child brought up in
Who carried out adoption study
Mendick et al
what was mendick et al’s study?
Studied 14000 adoptive children between 1924 and 1949
What was mendick et al’s findings?
-siblings more likely to have criminal record if parents have one - supports genetic theory
-only around 15% had one if adoptive parents did
Adoptees more likely to have criminal record if bio parents did
Strengths of twin and adoption studies
-give some support to genetic explanations
-research design is logical
limitations of twin and adoption studies
-if criminality strictly genetic MZ would have 100% concordance
-impossible to fully isolate genetic effects from environmental ones
What is a chromosome?
DNA that carries genetics inherited from parents. Most people have 23 pairs.
what is xyy syndrome
(supermale syndrome) when men inherit an extra Y chromosone from their fathers
what was Jacob’s key idea on xyy syndrome?
xyy makes men genetically pre disposed to criminality
what are the features of xyy?
tall, low intellegence, high aggression, violent
what was Jacob’s study?
compared rate of xxy in criminals compared to non criminals
what did jacob’s study find?
found that there was higher than avarage amount of inmates with xyy
what did prince and whitmore say that supports jacob’s theory?
xyy immature and unstable making them likely to commit motiveless property crime
Jacob xyy strengths
-Jacob found association between xyy and criminality
-prince and whitmore found evidence of correlation between xyy and property crime
jacob xyy limitations
-having the syndrome doesnt mean it caused the crime
-labels xyy as violent offenders
-syndrome too rare to explain most crimes
what is a case study example of brain injuries and criminality
Phineas gage
Metal rod went through frontal lobe, behaviour and personality changed with friends and family saying he was no longer gage and he engaged in behaviours he hadn’t been engaging with in the past.
what is the key idea of brain injuries in explaining criminality?
Damage to brain, especially prefrontal cortex, can change personality and behaviour and are more common in prisoners.
why did the rod alter phineas gage’s behaviour and attitude?
part of brain lost associated with mentala nd emotional functions
What is the key idea with brain disorders/ diseases in explaining criminality?
some brain disorders and diseases have been linked to criminal behaviour.
examples of brain disorders and diseases that can alter criminal behaviour
encephalitis lethargica, dementia, brain tumours
what does an EEG do
measures brain activity
how can EEG readings be linked to criminality?
some studies show abnormal readings in psychopathic criminals
brain injuries and disorders strengths
-few extreme cases show brain injury can resiult in criminal behaviour
-correlation betrween abnormal EEG and psychopathy
-prisoners more likely to have brain abnormalities than non criminals
brain injuries and disorders limitations
-crimes caused by brain injuries/diseases rare. More to do with personality
-abnormal EEG nor seen in all psychopaths
How can biochemistry explain criminality?
Biochemicals effect brain chemistry and mental processes
what is the key idea of biochemical explanations
biochemical substances and processes linked to criminality
what is testosterone and what types of crimes does it link to?
Male sex hormone when over produced linked to aggression and violent crimes
What do Ellis and Coontz say about male sex hormones?
testosterone peaks from puberty to early 20s which is the same as criminality
what is PMT
premenstrual tension- fluctuation in sex hormones
whats PND
Post natal depression- used as defence in infanticide
How are female sex hormones linked to criminality?
PMT, PND, Lactation used as defence in court as affect mood and self control
is low blood pressure hypoglycaemia or hyperglycaemia?
hypo
How is low blood pressure linked to criminality?
Hypoglycaemia linked to aggression and irritability
How is substance abuse linked to criminality?
Drugs and alcohol can lead to increased aggression and impulsivity
Biochemical explanations strengths
-biochemical recognised by courts
-sex hormones, drugs and alcohol, and blood pressure levels all known to increase aggression
Biochemical explanations limitations
-biochemical responses may need environmental explanation too
-some studies say testosterone not linked
-PND and infanticide could be caused by isolation not hormones
