Wednesday 30 September 2015

Evolutionary Theory

The evolutionary theory suggests that the behaviours and thinking that we currently have, have adapted an advantage in our evolutionary past. It focuses on: 

- Jealousy and infidelity.
- Aggression as an evolutionary advantage.
- Cuckoldry
- Mate retention tactics - violence and vigilance
- Individual survival
- Procreation potential
- Competition for limited resources
- Competing to increase own fitness
- Natural selection
- Adaptive trait
- Group display
- Warfare

Jealousy and infidelity 

Early human males lived in fear of losing their mate to another male - something that would have devastating consequences for them in terms of passing on genes. This may have led to sexual jealousy. Male sexual jealousy was caused by the female's suspected infidelity.

Research:
- Buss et al (1992) 
- Pipat

Group Display

There is a widespread belief that people behave differently when in groups compared to how they behave as individuals. Some behaviours only occur when like-minded people come together for the same purpose. This is often seen in: 

Hooliganism and Xenophobia

Research: 
- Marsh (1978) 
- Cialdini (1976)

Territoriality

- Threat displays - Protective response to an invasion of one's territory. Aggressive displays would have been adaptive for our distant ancestors because they allowed groups to defend valuable resources associated with their territory.

Research: 
- Neave and Wolfson (2003) 
- Pollard and Pollard (2005) 

Warfare

War is an extreme course of action contradictory to survival so it must be assumed that the benefits will outweigh the cost. Male warriors have been found to be more sexually attractive to females, making them more likely to get a mate and pass on their genes. Even in modern day, men fight to secure access to women. More than 20,000 Muslim women were raped in Bosnia by the Serbs in order for them to increase the number of Serbian babies born. 

Research: 
- Lehmann and Feldman (2008) 
- Kelly and Dunbar (2001) 
- Farthing (2005) 






Warfare - Studies

Lehmann and Feldman (2008) 

Men who are stronger and more aggressive will win wars and survive to pass on genes, leading to an increasingly aggressive species. Two traits that have evolved in humans that determine the likelihood of conflict: 
- Belligerence
- Bravery 
Men with both traits have a higher chance of winning. 

Kelly and Dunbar (2001) 

Claim that bravery or heroic acts my have evolved owing to a female preference for brave, risk prone men. It is more likely that males that are willing to commit such 'brave' acts will also protect them in times of danger. 

Farthing (2005) 

Surveyed whether men and women desired physical risk tears as partners. The result was that only when the risks were considered 'brave' there was a significant advantage in mate selection. Physical risks that were not considered 'brave' were not an advantageous mate quality. 

Group display - studies

Marsh (1978) 

Football hooliganism is the human equivalent of 'ceremonial conflict' in animals and involves trials of strength over territory. 

Cialdini et al (1976) 

After a university football team had performed well, students were more likely to wear university scarves and sweaters - 'basking in reflected glory'. 

Neave and Wolfson (2003) 

Found that football teams playing at home were far more likely to win than the visiting team partly because players have the benefit of a huge surge in testosterone before the match. They believed this could be due to an evolved drive to defend home territory. 

Pollard and Pollard (2005) 

The relationship with crowd sir is unclear as the advantage had been shown to operate even with very small crowds. 

Jealousy and Infidelity - studies

Buss et al (1992) 

Procedure
- Asked male and female students the question 'what would distress you more?'
'(a) imagining your mate having sexual intercourse with someone else'
or
'(b) imagining your mate forming a deep emotional attachment to someone else'

(a) represents a threat to paternity security
(b) represents a threat to domestic paternity

Findings

- 60% of men said A
- 80% of women said B
- 40 % of males who didn't choose A - most had never experienced a committed sexual relationship and therefore unlikely to experience sexual jealousy.
- Suggests even if there is an underlying evolutionary mechanism behind male sexual aggression, it is modified by experience.

Pipat

Pipat given a decrease sentence for killing his wife dye to his young children and a 'fit of jealousy'.

Wednesday 23 September 2015

Adoption - studies

Mednick et al (1975) 

From 14,000 adoptions in Denmark, it was found that a significant number of adopted boys with criminal convictions had biological parents with criminal convictions. 

Miles and Carey (1997) 

Procedure
- Meta-analysis of 24 twin adoption studies.
- Concerned with genetic basis of aggression.

Findings
- A strong genetic influence accounted for as much as 50% variance in aggression.
- Both genes and family environment were influential.
- At later ages, influence of rearing environment decreased and influence of genes increased.

Brennan and Mednick (1993) 

A series of adoption studies in which the criminal history of an adopted male was compared with criminal history of both biological and adoptive fathers, found that genetic influences were significant in cases of property crime but not in violent crime. 


Adoption studies have shown the highest rates of criminal violence in adopted children occur when both biological and adoptive parents have a history of violent crime - clear evidence of a gene-environment interaction. 

Tuesday 22 September 2015

Twin - Studies

Berkowitz (1993) 

Studies from the 1930s found an average concordance rate of 75% for MZ twins and 24% for DZ. Support that genetics do influence levels of aggression. 


McGuffin and Gottesman (1985) 

Found a concordance rate of 87% for aggressive and antisocial behaviour for MZ twin pairs, compared with DZ twin pairs (72%). 
Findings also indicate that family environment, shared across siblings, exerts an important influence. 
Studies support the importance of genetic factors in aggression - but also environments that siblings share. 

Meta analysis by Mason and Frick (1994)

Procedure
- Analysed 12 twin studies involving 3795 twin pairs.

Findings 
- Approximately 50% of the difference between antisocial and non-antisocial behaviours could be attributed to genetic factors.

Coccaro et al (1997) 

In one of the twin studies, Coccaro assessed the degree of genetic and environmental influences on aggression in male participants. Data from 182 MZ twin pairs and 188 DZ twin pairs were analysed. 
Genes accounted for more than 40% of individual differences in aggression. 
Environment accounted for 50% of individual differences in physical aggression and 70% in verbal aggression. 

Genetic Causes of Aggression

XYY Karyotype

Sandberg (1961): First identified what is scientifically known as the 47 XYY Karyotype. Most individuals have 46 chromosomes (23 from each parent). Female have XX and male XY. It is possible for males to have an extra Y chromosome (making XYY).

The link between XYY males and increased aggressiveness was an early assumption that Court-Brown made prior to the examination of the patients. This point was later retracted, although it was too late because many scientists had already incorporated this incorrect view into their thinking. While the gene has actually only been proved to have effects on height and acne, but the stigma is still there and men with the XYY chromosome are assumed to be more aggressive despite research opposing this.

Research in this  area is conflicting so it is not possible to conclude that the XYY gene causes aggression. Using projective tests, Theilgaard showed that XYY men tend to give more aggressive interpretations of the images compared to XY males.

Research: 
- Court-Brown (1965-1967)
- Theilgaard (1984) 


Twin Studies

Monozygotic twins share all of their genes.
Dizygotic twins share 50% of their genes.

If a researcher compares the similarity between sets of MZ twins to the similarity between DZ twins for  a trait like aggression and finds that  MZ twins are more alike, then this likeness should be due to genetics rather than environmental factors. Most twin studies have focused on criminal behaviour.

Research: 
- Berkowitz (1993) 
- McGuffin and Gottesman (1985) 
- Meta analysis by Mason and Frick (1997) 
- Coccaro et al (1997) 


Adoption Studies

A way of studying genetic factors in aggressive behaviour is by studying children who have been brought up by adults who aren't their biological parents. Adoption studies can help to untangle the relative contributions of environment and heredity in aggression. If a positive correlation is found between aggressive behaviour in adopted children and aggressive behaviour in their biological parents, a genetic effect is implied.

Research
- Mednick et al (1975) 
- Miles and Carey (1997) 
- Brennan and Mednick (1993) 

XYY Studies

Court-Brown (1965-67)

A sample of 314 patients with XYY would be 'best hospitalised due to an increased likelihood of aggressive behaviour'. The request for hospitalisation was based upon common knowledge of traits associated with each of the sexes. 

Theilgaard (1984)

Researched the personality traits of a sample of XXY men and compared these to a sample of XY men and men with XXY. Part of the research compared the aggressiveness of the XYY to XY men. Theilgaard's background research showed that about 1 in 1000 males are XYY and that no single characteristic except height has been associated with XYY. Aggression levels fluctuate.


Also used the Rorschach test, in which XYY males gave more aggressive interpretations than XY counterparts. 

Saturday 19 September 2015

Hormonal Mechanisms - Studies

Dabbs et al (1987)

Measured salivary testosterone in violent and non-violent criminals. Violent criminals had higher levels of testosterone. 

Lindman et al (1987) 

Young males who behaved aggressively when drunk had high testosterone levels. 

The challenge hypothesis (Wingfield et al, 1990) 

In monogamous species, testosterone levels should only rise above baseline levels in response to social challenges. Males are expected to increase testosterone upon male-male conflict or 
reproductive success. 


Kouri et al (1995)

Procedure
- Double-blind procedure using young men.
- Given either testosterone or placebo.
- Paired with fictitious participant and told that each member of the pair could reduce the amount of cash the other received by pushing a button.
- Also told that the other participant was reducing the cash that the participant was receiving.

Findings
- Participants who received testosterone rather than the placebo pushed the button significantly more times.

Olweus et al (1980) 

Procedure
- Measured blood testosterone levels in 16-year-old boys.
- Assessed aggression using a questionnaire.

Findings
- Higher levels of self-reported physical verbal aggression were associated with higher levels of testosterone.

Baucom et al (1995)

Women with higher testosterone levels has higher occupational status, possibly as a result of  assertiveness. 

Albert et al (1993)

Despite many studies showing a positive correlation between aggression and testosterone levels, other studies find no such relationship and most studies showing a positive correlation involved small samples of men in prisons using self-reports of judgements on severity of the crime. 




_____________________________


Van Goozen (2007)

Thers is a link between aggression and cortisol. 

Virkkunen (1985)

Low levels of cortisol in habitually violent offenders. 

Tennes and Kreve (1985)

There are low levels of cortisol in aggressive schoolchildren. 

McBurnett et al (2000) 

Procedure

- Evaluated 38 boys aged 7 to 12 for problem behaviour.
- Behaviours evaluated annually for four years.
- Salivary cortisol measurements taken during second and fourth years.

Findings 

- Boys with lower cortisol levels exhibited three time the number of aggressive symptoms compared to boys with higher levels of cortisol.
- Boys with low cortisol were also named the most aggressive and 'meanest' by peers.

Gerra et al (1997) 

Procedure

- Actually reported high cortisol = higher aggression.



Wednesday 16 September 2015

Biological Causes of Aggression

Neurotransmitters

Dopamine

High levels of dopamine are linked to high levels of aggression. Dopamine is often released in response to rewarding stimuli such as food, sex and recreational drugs. 

Studies
• Couppis et al (2008)
• Couppis & Kennedy (2008)
• Ferrari (2003) 

Evaluation
- Use of animals
- Nature/Nurture
- Free will/Determinism

Serotonin 

Low serotonin can result in impulsive behaviour, aggression, overeating, depression, alcohol abuse and violent suicide. e.g. Silver foxes tamed by humans for more than 30 years - found high levels of serotonin. 

Studies
• Linnolia & Virkkunen (1992) 
• Cleare & Band (1997) 
• Summers et al (2005)
• Davidson (2000)

Evaluation
- Nature/Nurture
- Free will/determinism
- Ethics



Brain Structure 

Amygdala:  Direct stimulation of an area of the amygdala in can make people more aggressive. It is more active during 'red alert' - when an animal attacks another. People are also armed to be more aggressive for 5-20 minutes after being provoked. Research: Protegal (1996).
Charles Whitman.

Hypothalamus: The hypothalamus has been shown to cause aggressive behaviour when electrically stimulated, but more importantly, has receptors that help determine aggression levels based on their interactions with serotonin. Research: Siegel & Pott (1988).

Cortex: The cortex seems to inhibit emotion and aggression. Research: Bard (1930s).




Hormonal Mechanisms

Testosterone: The male sex hormone testosterone is thought to influence aggression from young adulthood. Males produce testosterone in the testes and women also produce testosterone but in smaller amounts. Testosterone is an androgen hormone and peaks in males between 15 and 25. 
Research: Dabbs et al (1987); Lindman (1987); The Challenge Hypothesis

Cortisol: Cortisol is produced by the adrenal medulla and is an important part of the body's response to stress. Lower cortisol levels are related to higher levels of aggression. 
Research: Van Goozen et al (2007); Virkkunen (1985); Tennes and Kreve (1985)








Brain Structure - Studies

Protegal (1996)

Direct stimulation of an area of the amygdala in hamsters produces aggressive behaviour. 

Charles Whitman (1966)

Killed 16 people by gunshot from the top of a building and left a note asking to inspect his brain. A tumour was found pressing on his amygdala

Siegel & Pott (1988)

The stimulation of the ventromedial hypothalamus results in spontaneous aggression. 

Phillip Bard (1930s)

Procedure
- Removed the cortex in cats and made them decorticate.

Findings
- Cats became aggressive and exhibited 'sham rage'.
- Arched backs, hissing, growling and bared teeth.

Phineas Gage 

Had his amygdala impaled by a pole working on a railway line and became extremely aggressive.

Neurotransmitter Studies

Couppis et al (2008)

Some individuals intentionally seek out aggressive encounters because of the rewarding sensations caused by dopamine. 

Couppis & Kennedy (2008)

In mice, a reward pathway in the brain is engaged in response to an aggressive event and dopamine is a positive reinforcer. 

Ferrari et al (2003)

Procedure
- Rats used.
- Forced to fight at the same time every day for 10 days.
- Not allowed to fight on the 11th day.
- Measured dopamine and serotonin.

Findings
- In anticipation for the fight, the rats; dopamine increased and serotonin decreased.


_____________________________

Linnolia & Virkkunen (1992)

Low levels of serotonin are linked to 'impulsivity and explosive acts of violence'.

Cleare & Bond (1997)

'Serotonin depletion tends to ruffle people's feathers'.

Summers et al (2005)

Observed that globally acting serotonergic drugs do modify aggressive behaviour. 

Davidson (2000)

Neurotransmitter research ignores the influence of brain structure.

Wednesday 9 September 2015

Studies - Institutional Aggression


Mills, Kroner & Weeks (1998) 

Procedure

- Surveyed 202 inmates newly admitted to Canadian prison
- Used Alcohol Dependence Scale

Findings

- Higher levels of misconduct were associated with more severe levels of alcohol dependence. 
- Employment record, a lower level of education and a more serious criminal record were also linked with a greater likelihood of aggression when imprisoned. 

Harer and Steffensmeier (2006)

Procedure 

- Collected data from 58 US prisons

Findings

- Black inmates had significantly higher rates of violent behaviour but lower rates of alcohol and drug related misconduct than white inmates.

Delis (2004) 

Procedure 

- Studied prison records of 831 male inmates from south western USA to explore prison violence records of inmates involved in street and prison gangs. 

Findings 

- Significant relationship between gang membership and institutional aggression - suggesting subcultural values had been imported into prisons. 


Poole and Regale (1983) 

They assessed the relative impact of several deprivation and importational variables on inmate violence in four juvenile correction centres. Both sets of variables were shown to exert some effects on inmate aggression but pre-institutional violence emerged as the best predictor of inmate aggression. 

_____________________________


Richards (2007)

Procedure

- Examined assaults in 900 US prisons.

Findings 

- Some inmate programmes increased rates of assaults while other decreased them. This suggests it is the characteristics of the prison that accounts for the levels of aggression. 

McCorkle (1995)

Found that overcrowding , lack of privacy and lack of meaningful activity all significantly influence peer violence, supporting the deprivation model. 

Also looked at individual and group aggression in 370 US prisons. Results demonstrated that the deprivation model didn't fully explain prison violence but there was a link between prison procedures and levels of aggression. 

Institutional Aggression

The Importation Model (Irwin & Cressey 1962)

- Prisoners bring their own social histories and traits with them into prison and this influences behaviour.
- They have a 'ready made' way of behaving and bring it into the institution.
- Race and age affects behaviour - young, non-whites are more likely to be aggressive in prison.
- Kane and Janus suggest that this is because groups become disenfranchised from mainstream society's norms.

Irwin and Cressey identified 3 prisoner subculture categories:

1) The Criminal or Thief Subculture (values inherent in professional their, trustworthy to fellow criminals.)
2) The Convict Subculture (raised in prison system, seek position of power, influence and information within institution. Most likely to turn aggression to cope.)
3) The Conventional/Straight Subculture (one time offenders, not part of criminal subculture before entering prison, identify more with prison staff, tend not to be aggressive in prison.)

Supported by:
Mills, Kroner & Weeks
• Harer and Steffensmeier
• Delis 
• Poole and Regale


The Deprivation Model (Sykes) 

Situational factors must influence prison behaviour, this involves organisational factors like leadership, management, physical factors (security, resources) and staff characteristics, (gender, race etc.) 

Aggression occurs as a result of internal factors within the prison setting and its due to the environment. Aggressive behaviours originates in the deprivations they experience (e.g. lack of relationships).

Sykes's outlines five deprivations - 

1) Deprivation of liberty - prisoners cannot live in the world like normal people and have to experience loss of civil rights, and loss of identity.
2) Deprivation of autonomy - no power or choice. Everything is controlled.
3) Deprivation of goods and services - no material possessions.
4) Deprivation of heterosexual relationships - no companionship - reduce self-worth
5) Deprivation of security - fear for own safety

Supported by:
• Richards
• McCorkle


Real life application - 

Abu Ghraib

Behaviours at Abu Ghraib were result of:

Status and power - soldiers had little power so asserted it over prisoners.
• Revenge and retaliation - hurting/killing fellow US soldiers
Deindividuation and helplessness

However, the institutional aggression may come from the individuals, not the institution itself.

Dehumanisation and genocide

If the target group is dehumanised, they are seen as unworthy of moral consideration and disposable. In the Rwansan genocide, the influential Hutu-controlled 'hate' radio station encouraged listeners to murder their Tutsi neighbours by referring to them as 'cockroaches'. Examples like this can also be found in world war II.