Biological explanations of crime and anti-social behaviour

• Brain injuries- caused by illness/accidents /drug abuse
• Alchol; toxic effect on CNS- inteferes with absortion of vitamin B1- thiamine; important brain nutrient
• Brain injury; behaviour becomes reckless and aggressive e.g. injury to amygala = increase in impulsive behaviour/ irritability and aggression
• Williams et al; 60% prisoners with traumatic brain injury due to falling, car accidents- younger at prison entry & higher rates of recividism
• Also suggested these injuries affected temperence, social judegement and controlling impulses, as well a greater level of risk taking beh- more likely for indiv. to be involved in antisocial activity 
• Impairment of these areas od developement- contributes to criminality 

• Offenders; comorbid conditions e.g. history of substance abuse/ pre-existing personality disorders/ poor upbringing; exposed to violence during childhood
• Kreutzer et al; unable to prove/disprove cause & effect relationship- brain injury & violence; 20% of 74 patiens- arrested pre-injury, and 10% post-injury
• Couldn't conclude that brain injury causes crimimality/violence; instead substance abuse led to traumatic brain injuries, concluding that without presence of a substance abuse history; trauamatic brain injury wasn't a risk factor for criminal behaviour.

Pardini et al; Brain scans; smaller amygdala- indiv. with psychopathic personalities & higher levels of aggression

Behaviours noticed from childhood. Concluded; smaller amygdela 3x more likely to exhibit aggression/violence & psychopathic tendancies.

Cannon & Britton; 'sham rage' animals in emotional state- severed neural connections to cortex in cats; when prevoked= agressive raging beh.

Souce of rage from temporal region- amygdala; when removed; more placid beh.

Amygdala; hostile beh.

Prefrontal cortex Is active in violent offenders but not in psychopaths

PFC; governs social interactions & regulates beh. Linked to impulsivity

Damage to this area; problems with anger management & impulse control & irritability

Phineas Gage; iron rod throught this area caused him to be angry & aggressive man contrary to his previous well-mannered temper

Raine et al; NGRI ppts; lower levels of glucose metabolism in prefrontal cortex- impulsivity & abnormal functioning in amygdala & hippocampus- explain why they commited murders

Sham rage studies lack generalisability to humans. Animals inlike humans don't have the capacity to inhibit their aggression with higher order thinking; thus those studies can't extrapolate findings to humans

Narabaysishi et al; similar result in humans; removed amygdala from aggressive ppts- mood stabalising effect in majority of ppts over time

Brain structures contribute to aggression but other factors involved

e.g. Fallon; some have abnormalities yet don't act in callous unemotional way- no cause and effect relationship est.- structural abnormalities causes criminality- Fallon misidentified a psychopath via brain scan as it was his own brain scan

Hare; not all psychopaths active in criminal population. Some suitable for hgih level management positions- tyipcal lack of fear- extreme sports etc

Humans; 23 pairs of chromosomes

23rd- sex chromosome- **; female, xy; male

XYY syndrome; genetic condition that occurs when there's extra Y chromosome in 23rd pair

Thus- they have 47 chromosomes; occurs 1/1000 males.

Not inherited- occurs randomaly at conception

Many are unaware they have XYY syndrome

Side effects; may grow faster/taller/ lower level of intelligence/ behaviour problems, easily distacted

XYYs= overtly aggressive & lack of empathy- Super-male sydrome 

Impractical to test the genes of all male offenders with XYY S as it requires skilled staff & resources-Therefore we're unlikely to know the real effect of all XYY S offenders

Theilgaard; small prevelence of XYY men in criminal population- Suggests there's other factors causing criminality 

Also criminal women- doesn't explain their criminality- this not generalisable/holistic explanation of criminality

Twin studies; MZ twins share 100% genetic info. DZ-50%.

If MZ twins- more alike agressive beh. than DZ, likely due to genes rather than environment

Adoption studies; twins split up from birth; different socialisation yet both aggressive suggests due to genetics

Hutchings and Mednick; 85.7% male adoptees with criminal offences had birth father with criminal record- link between criminal behaviour and genetics

NTM; chemicals that trigger a response in brain e.g. serotonin & dophamine

Serotonin; manages mood ; happiness chemical. Low; aggression more likely to commit crime/anti-social beh. Serotonin inhibits impulses other than aggression- so low levels can result in an over-reaction in emotiona situations including aggression

Dophamine; learning & brain's reward system; pleasure produced in response to rewarding stimuli e.g. food/ drugs. Lavine; increase in dophamine via amphetamines increased aggressio & positive reinforcement for agression- agression generates increased dophamine levels- activiates brain's reward system

Testosterone; high levels cause aggression

Men have higher levels of tesosterone 15-25 years old- age they're most involved in violence.

Levine; increased dophamine levels via amphetamines- associated with aggressive behaviour & serves as positive reinforcement for aggression; being aggressive generates increased dophamine-activiating brain's reward system

Cleare and Bond; males with no history of psychiatric problems= low serotonin levels- correlate with levels of agression & hostility

Dabbs et al; higher levels of testosterone in violent prisoners

Kennedy; dophamine levels in mice increased & act as reward system during aggressive acts - increased dophamine levels aren't cause of aggression- concequence of it

Skarberg; Studies; indiviv on anabolic steroids= more likely to engage in violent acts

Beaver et al; Anabolic steroids; synthetic forms of testosterone- promote body and strength growth

Some criminals use violence to achieve a specific goal like killing for money- so testosterone explantioms are reductionist- not a full explanation for violent behaviour since aggression doesnt always corellate with violence 

Albert et al; castration in rats= reduction in agggressive beh & few attemts to display social dominance

Soler et al; male offenders- higher levels of saliva tesosterone than males without domestic violence convictions 

Extraversion; beh is outgoing, socilable & active. Indiv. wants excitement & easily becomes bored

Introversion; indiv. usually reseved & reflective. Introverts more likely to prefer solitary to socialising 

Neurotisicm; emotional instability associated with anxiety, fear, depression & envy 

Stability; indiv. is emotionally calm. unreactive and unworried

Psychoticism; lack empathy- aggressive & impersonal & cold- men commiting serial sexual homicide usually show psychothapy

Eysenck- PEN Personality; 3 chacteristics- psychoticism (P), extraversion (E), and neuroticism (N)- influenced by our biology- can explain criminality. 

Arousal theory; indiv. are motivated to act in a way to maintain a certain level of physiological arousal. When arousal levels drop below optimum, we engage in stimulating beh to increase arosual. 

Eysenck- Arousal Theory; Linked to ARAS; Ascending Reticular Activating Sytem; a sytem that transmits messages to the limbic system, triggering the realise of hormones & neurotransmitters. Activity in ARAS- stimulayes cerbral cortex- higher cortical arousal

Extraverts- underactive ARAS- require greater levels of external stimulation 

Eysenck; explained neuroticism in terms of activation thresholds in the sympathetic nervous system- limbic system; hippocampus, amygdela and hypothalamus. system where fear and aggression are regulated & fight or flight response. Neurotics- greater activation levels & lower thresholds within LS. They're easily upset from minor stresses compared to stable people- calm under stresses becuase they have lesser activiation levels and higher thresholds

Eysenck; biological explanation for psychoticism- hormones e.g. testosterone and enzymes e.g. monoamine oxidase (MAO); people showing psychotic episode have increased testosterone and low MAO levels

Rushton & Chrisjohn- investigated delinquent not criminal beh, but their study supported a relatonship between high delinquency scores and high scores on extraversion and psychoticism- but not a link with neuroticism- key differences between 3 personality dimensions

Boduszek et al.- investigated personality traits in predicting violent offending within a sample of recidivistic inmates. Higher levels of extraversion predicted greater possibility of commiting violent criminal act. 

Farrington- E scores are less associated with criminal convicitons than P and N

PD; indiv. way of thinking, feeling or relating to others differs significantly from sb. without a PD. It s a clinical diagnosis, reflecting extremes in people's personalities 

Narcissstic- a need to be admired, thinks they're the most important and will exploid others to get what they want 

Anti-social; often aggressive, ignore rules and don't care about others

Paranoid; distrust of others, suspicious, takes criticisms very personally and can bear grudges

Stone; antisocial and paranoid PDs are the most common PDs amoung violent offenders; Intrumental muderers who killed their partners were strongly associated with narcissism; mass murders usually show strong paranoid traits 

Eysenck's explantion of personality- simplistic & fails to consider that a person's reactions & beh. may differ depending on the situation.

It doesn't consider biological issues e.g. brain injury to contribute to why an individual may be more extravert and less inhibited, or social explantions for criminality- reductionist 

Personality research; based on self-report data. Info given by indiv.- flawed; respose bias, or social desirability bias- not want the research to delve into their personality- thus the findings are less reliable 

Some studies- personality= contributory factor not causal for aggression. these studies- focus on social & biological factors- placed importance of personality within context of wider influences