Aggression A03 Flashcards
(8 cards)
Neural influences - Role of amygdala
P) Pardini et al (2014) found that reduced amygdala volume can predict the development of aggression.
E) Longitudinal study of male participants from childhood to adulthood - 56 of the participants with varying histories of violence were subjected to a brain MRI at 26
E) pps with lower amygdala volumes exhibited higher levels of aggression and violence - this remained even after other confounding variables were controlled.
L) Amygdala plays an important role in evaluating the emotional importance of sensory information, and lower amygdala volume compromises this ability, making a violent response more likely.
Neural influences - Role of hippocampus
P) Raine et al. (2004) provided support for the role of the hippocampus in aggressive behaviour in their study of violent offenders.
E) They studied two groups of violent criminals; successful psychopaths (cold, calculating criminals) and unsuccessful psychopaths (acted impulsively)
E) Unsuccessful group - MRI scans revealed the hippocampus in either hemisphere differed in size, presumed to have arisen early in brain development.
L) Asymmetry might impair the ability of the hippocampus and the amygdala to work together –> emotional information is not processed correctly –> inappropriate verbal and physical responses
Neural influences - Studies of non human species
P) There is evidence to support neural influences from studies of non-human species
E) Raleigh et al. (1991) found that vervet monkeys fed on diets high in tryptophan (increases serotonin) exhibited decreased levels of aggression, and individuals fed on diets that were low in tryptophan exhibited increased aggression
E) Rosado et al. (2010) compared a sample of 80 dogs of various breeds that had aggressive behaviour towards humans with a control sample of 19 dogs of various breeds that did not show aggressive behaviour. The aggressive dogs averaged 278 units of serotonin, while the non-aggressive dogs averaged 387 units.
L) Different levels of aggression found could be attributed to the animals’ serotonin levels.
Hormonal influences - Positive relationship
P) There is evidence to show a positive relationship between testosterone and aggression
E) Albert et al (1994) found positive correlations have been reported between levels of testosterone and self-reported levels of aggression among prison inmates.
Olweus et al (1988) found this relationship between testosterone levels and the likelihood of responding aggressively to provocation
E) However, no correlation was found between testosterone levels and actual violent behaviour among male inmates
L) Relationship between testosterone and aggression may actually remain inconsistent and unclear
Hormonal influences - Aggression and dominance
P) Mazur (1985) suggests that it’s important to distinguish between aggression and dominance.
Aggressive - intend to inflict injury Dominant - wish to achieve or maintain status
E) Non-human animals - testosterone on dominance might be shown through aggressive behaviour
Humans - dominance is expressed in more varied and subtle ways, including status seeking behaviour
E) Eisenegger et al (2011) found that testosterone makes women act ‘nicer’ rather than more aggressively in some situations
L) This supports the idea that instead of increasing aggression, testosterone promotes status-seeking behaviour, and aggression is one type of this
Genetic factors - Explanation for uneven rates
P) An advantage of MAOA gene research is that it offers an explanation for the uneven rates of violence for males and females
E) Niehoff (2014) - differential genetic vulnerability that males and females have to MAOA gene, which is linked to the X chromosome, which women have two of and men only have one
E) When men inherit an X-linked gene from their mothers, they are likely to be affected by it, whereas women inheriting the same gene are generally unaffected, as they have a second X chromosome that prevents expression of the abnormal version of the MAOA gene
L) This could explain why males typically show more aggressive behaviour than males
Genetic factors - Research support
P) Recent study in Finland has added research support that the MAOA gene is implicated in severe violent behaviours
E) Tihonen et al. (2015) studied Finnish prisoners, revealing that MAOA-L in combination with another gene (the CDH13 gene) was associated with extremely violent behaviour.
E) There was no substantial evidence for either of these genes among non-violent offenders, indicating that this combination of genes was specific for violent offending only.
L) However, critics argue that although these genes may make it harder for some people to control violent urges, they do not predetermine violent behaviour.
Genetic factors - Inconsistencies in the methods
P) One limitation is that there are inconsistencies in the methods used to study genetic factors in aggression
E) In Miles and Carey’s meta-analysis, the mode of assessment was found to have potentially influenced the outcomes in the 24 studies analysed
E) They found that studies that used parental or self reports found that genetic factors explained aggressive behaviour. However, those that had used observations found a greater influence of environmental factors
L) Therefore, inconsistent findings make it hard to assess relative contributions of genetic and environmental factors in aggression
