Aggression

    Cards (44)

    • Define Limbic System
      subcortical structures in the brain thought to be closely involved in regulating emotional behaviour e.g. aggression
    • Define serotonin
      neurotransmitter with widespread inhibitory effects throughout the brain
    • Define Testosterone?
      hormone from the androgen group that is produced mainly in the male testes e.g. associated with aggressiveness
    • What are meant by genetic factors in aggression?
      > Gene consists of DNA strands.
      > DNA provides instructions for general physical characteristics of organism e.g. eye, height and also features such as neurotransmitter levels and size of brain structure.
      > These may impact on psychological features such as intelligence and mental disorder. Genes are transmitted from parents to offspring i.e. inherited
    • What do twin studies tell us about genetic factors in aggression?
      > Often used to see if there is genetic basis for aggression.
      > Coccaro et al (1997) found up to 50% of variance in aggressive behaviour can be explained by genetics.
      > 50% concordance rate amongst identical (MZ) twins, and 19% concordance rate for non-identical (DZ) twins for physical aggression.
      > For verbal aggression, concordance rates were 28% for MZs and 7% for DZs.
      > This suggests a genetic link, as twins would share environments, but MZs share a greater proportion of genes.
    • What do adoption studies tell us about genetic factors in aggression?
      > Similarities in aggressive behaviour between adopted child and biological parents = genetic influence.
      > Similarity between adopted child adoptive parent = environmental influence.
      > Rhee and Waldman - through their meta-analysis of adoption studies of aggression and anti-social behaviour, they found 41% of variance in aggressive behaviour can be due to genes, suggesting genetic link.
    • What does the MAOA gene tell us about genetic factors in aggression?
      > MAOA gene controls production of an enzyme called monoamine oxidase A (MAO-A)
      > MAOA breaks down (reduce) serotonin leading to a lower level of serotonin in the synapse
      > Low level of serotonin = lower level of aggression
      > Genes come in different variants. Low activity variant (MAOA-L) is linked to high levels of aggressive behaviour. Means less serotonin is broken down which leads to high levels of serotonin in synapse = increased aggression
      > MAOA gene also known as warrior gene.
    • Describe the research support for the MAOA gene?
      > Brunner et al
      > Found 28 men from Dutch family were involved in impulsively aggressive behaviour - e.g. rape, attempted murder and physical assault.
      > Found to have lower levels of enzyme MAO-A & MAOA-L.
      > Suggests MAOA-L variant leads to higher aggression levels
    • What do gene-environment interactions tell us about aggression?
      > Low MAOA activity is linked with aggression only in combination with an environmental influence, e.g. a traumatic life event.
      > Frazzetto et al found link between low-activity MAOA gene variant and aggression, but only in those who experienced childhood sexual or physical abuse.
      > Those who had not been abused did not show high levels of aggression, even with low-activity MAOA gene.
      > Suggests interaction between genes and environment, supporting a diathesis-stress explanation.
    • Give a weakness of genetic factors in aggression
      P - Very hard to establish how influential genes are in aggressive behaviour.
      E - Genes may only create vulnerability to aggression, when combined with certain environmental influences.
      E - E.g. McDermott et al found pps with low-activity MAOA gene behaved aggressively in lab-based task, but only when provoked. Otherwise, they were no more or less aggressive than other pps.
      L - Decreases validity of genetic factors aggression as researchers have difficulty separating genetic and environmental factors.
    • Give a strength of genetic factors in aggression
      P - research support for role of MAOA gene in aggression.
      E - Mertins et al found when men with low and high activity variants of MAOA gene took part in a money-distributing game, men with high activity variant were more cooperative and made fewer aggressive moves than low-activity participants.
      E - This is in line with MAOA gene hypothesis which states that low activity variant is associated with increased levels of aggression.
      L - Shows there is relationship between MAOA gene activity and aggression.
    • Give a weakness of genetic factors in aggression
      P - there are other genes involved in aggression other than MAOA.
      E - Another gene involved in aggression is serotonin transporter genes (5-HTT), this gene influences serotonin activity in brain. Combination of these 2 genes is may be why aggression levels can be high.
      E - E.g. Stuart et al studied intimate partner violence in men and found they had low levels of MAOA gene and low levels of serotonin transporter genes.
      L - Singling out MAOA gene and saying this is sole genetic reason for aggression to occur is not reliable explanation.
    • Give a weakness of genetic factors in aggression
      P - methods of measuring aggression differ significantly between studies e.g. self-reports, parent and teacher reports, and direct observation.
      E - Rhee and Waldman's meta-analysis of 51 twin and adoption studies. Genetic factors had greater influence on aggression in studies using self-reports rather than parent or teacher reports.
      E - This is weakness as if research findings vary depending upon how aggression is measured, then it becomes very difficult to draw valid conclusions about role of genetic factors in aggression (or other factors for that matter).
    • What is meant by ethology?
      Study of animal behaviour in natural setting.
      > This explanation suggests aggression has an adaptive function.
    • How did Lorenz define aggression?
      "The fighting instinct in beast and man which is directed against members of the same species."
    • What is meant by aggression having an adaptive function?
      > Aggression is an instinct- doesn't need to be learnt.
      > It is innate and so genetically determined.
      > Aggressive behaviours are adaptive as they are helpful to survival of a species.
      > In examples of aggression, defeated animals are rarely killed. This is adaptive, as defeated animal will move elsewhere, spreading out species over a larger area and reducing competition pressure for resources.
      > Aggression is also used to establish dominance hierarchies, allowing animal to have high status and so access to more resources and potential mates.
    • Explain ritualistic aggression
      > Lorenz observed that fights between animals of same species usually involve little physical damage.
      > Most aggressive encounters consisted mainly of ritualistic signalling (displaying claws and teeth, facial expressions of threat).
      > Pointed out intra-species aggressive confrontations end with ritual appeasement displays. These indicate acceptance of defeat and inhibit aggressive behaviour victor, preventing
      any damage to loser.
      > Example: At end of aggressive confrontation, wolf will expose its neck to victor, deliberately making itself vulnerable to single bite to its jugular vein.
      > This is adaptive because if every aggressive encounter ended with death, it could risk end to an entire species.
    • What are innate releasing mechanisms?
      > inbuilt physiological process which gets triggered by an external stimulus.
      > The IRM then releases a specific sequence of behaviours called a fixed action pattern
    • What is meant by a fixed action pattern?
      A sequence of stereotyped pre-programmed behaviours triggered by an innate releasing mechanism.
    • What are the main features of a fixed action pattern?
      According to Lea FAPs have 6 main features:
      > Stereotyped - unchanging sequences of behaviour.
      > Universal- same for every animal of that species
      > Unaffected by learning - same for every individual of a species.
      > 'Ballistic': once behaviour is triggered it follows inevitable course and can't be altered before its completion.
      > Single - purpose: behaviour only occurs in specific situation and not in any other.
      > Response to a specific stimulus
    • Describe the research into innate releasing mechanisms and fixed action patterns?
      > Tinbergen (1951) investigated sticklebacks, which develop red areas on their underbellies during mating season, and become aggressive towards males entering their territories.
      > Red on competing male's underbelly is stimulus that triggers IRM that in turn leads to the aggression FAP ritualistic behaviour.
      > found that, when presented with wooden models of various shapes, male sticklebacks would aggressively display and attack model if there was red area underneath it (even if it looked nothing like a fish).
      > They didn't attack stickleback-shaped models if there was no red underbelly.
    • Give a weakness of ethological explanations of aggression
      P - evidence against idea that aggressive displays do not result in physical violence (ritualistic aggression).
      E - During 'four-year war' at a national park in Tanzania, Goodall (2010) observed examples of violent aggressive acts by chimpanzees towards each other even when the opponent showed clear signals of appeasement and defeat.
      E - These signals didn't inhibit aggressive behaviour of attacking chimps as predicted by ethological explanation.
      L - This challenges suggestion that aggressive displays do not lead to actual aggression.
    • Give a strength of ethological explanations of aggression
      P - Supporting evidence
      E - Research by Brunner et al showed low-activity variant of MAOA gene is closely associated with aggressive behaviour in humans, suggesting innate basis.
      E - Also, evidence for existence of IRMs for aggression in brain - activity in limbic system has been shown to trigger aggressive behaviour in humans and animals.
      L - As ethological explanation argues aggression is genetically determined and heritable, its validity is supported by evidence showing genetic and physiological basis of aggression.
    • Give a weakness of ethological explanations of aggression
      P - Findings can't be generalised to humans.
      E - Study was done on fishes, who are biologically different to humans and less complex than humans.
      E - Further backed up by the fact that Lorenz didn't continue this study with much more complex animals, such as primates. Doing research on animals that are biologically similar to humans makes research generalisable. However, since it's done on less complex animals it can't be generalised.
      L - Findings can be seen as far fetched on humans and making inaccurate assumptions without evidence.
    • Give a weakness of ethological explanations of aggression
      P - a more accurate description of FAPs may be 'modal' rather than 'fixed', as suggested by Hunt (1973).
      e - Hunt provided evidence that duration of each behaviour within each FAP may vary between individuals as well as the specific other animal towards which it is targeted.
      E - Environmental and social factors may have significant influences on course of FAP.
      L -This results in lower validity of universal nature of FAPs as part of an explanation for aggression.
    • What is aggression?
      > Behaviours that can result in both physical and psychological harm to self, other people, or objects in environment.
      > Expression of aggression can be physically, verbally, mentally and emotionally etc.
      > Two different types of aggression:
      - impulsive aggression = typically unplanned, strong emotions, normally anger.
      - instrumental aggression = usually carefully planned with intention of achieving a goal.
    • What is the limbic system?

      > Structures in the brain linked to emotional behaviours including aggression.
      > Many structures including:
      1: The amygdala
      2: Hippocampus
    • What is the role of the amygdala?
      > Plays a key role in how humans and animals respond to environmental threats and challenges.
      > Increased amygdala activity is associated with aggression.
    • What is the role of the hippocampus?
      > Involved with formation of LTM, and so allows one to compare a current threat with similar past experiences.
      > If someone has been attacked by a certain person they are likely to develop fear or aggression when they see same person again or someone who reminds them of person.
    • Describe the research done on the limbic system?
      > Gospic et al (2011)
      > lab study of assessing aggressive behaviour called Ultimatum Game.
      > An aggressive game where pp have to decide to split money with confederate. If both agree to share money, it is split between them. If pp refuses offer, both leave with nothing.
      > Whilst in study pp were having their brains scanned by fMRI, which highlights activity in different areas of brain.
      > More activity was seen in amygdala when confederate made an unfair offer, which pp then rejected.
      > Taking drugs to lower this activity (benzodiazepine) before game also lowered aggression - number of rejections halved and there was decreased activity in amygdala.
      > strong evidence of association between reactive aggression and amygdala activity.
    • Explain the neural mechanism involved in aggression
      > Neural Mechanisms - Orbitofrontal Cortex and Serotonin
      > A neurotransmitter thought to inhibit aggressive responses to emotional stimuli and increase self-control.
      > Low levels of serotonin are associated with increased susceptibility to impulsive behaviour and aggression.
      > Normal levels of serotonin in orbital frontal cortex are linked with reduced firing of neurons=self-control
      > Decreased (low levels of) serotonin disturbs this mechanism = no self-control = aggression (Densen et al, 2012)
    • Explain the hormonal mechanism in aggression
      > Testosterone is present in both males and females but is linked to aggression in males.
      > Testosterone is thought to act on areas of brain which control aggression
      > Castration studies of animals show that removing testes reduces aggression, and injecting testosterone in same animals will restore aggression (Giammanco et al).
      > Dolan et al found positive correlation between testosterone levels and aggression in 60 male offenders, suggesting link.
    • Give a weakness of neural mechanisms in aggression
      P - Recent studies have shown amygdala doesn't work on its own in determining aggression like first thought. It is suggested it works together with orbitofrontal cortex (OFC), which is not part of limbic system.
      E - Coccaro et al. found patients with psychiatric disorders that frequently show aggression, have reduced OFC activity.
      E - As OFC is thought to be involved in self-control and inhibition of aggressive behaviour, Coccaro's findings show reduced OFC activity disrupts its impulsive-control function and so leading to increased aggression.
      L - Suggests regulation of aggression is highly complex and involves at least 3 neural structures in brain: amygdala, OFC and connection between two.
    • Give a strength of neural mechanisms in aggression

      P - Research support for effect of serotonin on aggression.
      E - Berman et al. gave pps either a placebo or a dose of paroxetine (drug that enhances serotonin activity). Pps then had to take part in lab based game where electric shocks of varying intensity were given and received in response to provocation. Found that paroxetine pps consistently gave fewer and less intense shocks than those in placebo group.
      E - Shows drugs that increase serotonin have been found to reduce levels of aggressive behaviour.
      L- Shows there is a causal link between serotonin function and aggression.
    • Give a strength of hormonal mechanisms in aggression
      P - Support from animal research.
      E - Giammanco et al. found in male monkeys there is increase in testosterone levels and aggressive behaviour during mating season. In rats, castration of males reduces testosterone and also mouse-killing behaviour. Injecting female rats with testosterone increases mouse-killing.
      E - Evidence shows increase of testosterone is linked with higher levels of aggressive behaviour.
      L - Shows role of testosterone in increasing aggression in many different animals.
    • Give a weakness of hormonal mechanisms in aggression
      P - Mixed evidence between link of aggression and testosterone in humans.
      E - Carre and Mehta developed a dual-hormone hypothesis. Increased levels of testosterone lead to aggressive behaviour, but only when Cortisol levels are low. When cortisol is high, testosterone's influence on aggression is blocked.
      E - Shows combined activity of testosterone and cortisol may be better predictor of aggression rather than either hormone alone.
      L - Suggests simply explaining aggression through role of testosterone is limited and fails to recognise complexities of aggressive behaviour.
    • What is the evolutionary explanation of sexual jealousy?
      > Sexual jealousy is a major motivator of aggressive behaviour in males
      > Men have sexual jealousy as they can never fully know if they have 'fathered' a child - Paternity Uncertainty
      > May lead to cuckoldry (raising a child that's not his)
      > This contributes to survival of a rival's genes
      > An investment in a child which is not his is a waste in investments
      > sexual jealousy = more common in males
      > This drives aggression strategies men often use to retain their partners from straying.
    • Explain mate retention strategies
      Daly and Wilson suggest males have many mate retention strategies that they use to prevent a mate (her) from straying:

      > Direct guarding - Vigilance over partner's behaviour e.g. checking who they've been seeing, coming home early, keeping tabs on their whereabouts, tracking apps etc.
      > Wilson found that women who said their partners did use these tactics were twice as likely to suffer violence partner.
      > Negative inducements - violence or threats of violence to prevent straying.
      > Camilleri (2004) found that sexual assault of female by her male partner was directly linked with perceived risk of her infidelity.
    • Describe the research into intimate partner violence
      > Shackelford et al (2005) studied intimate partner violence in heterosexual couples.
      > P: Men and women in 107 married couples completed different questionnaires- men completed 'Mate Retention Inventory' (assessing mate retention behaviours in various categories, e.g. direct guarding). Women completed 'Spouse Influence Report' (measuring extent of their partner's violence in their relationship). All pps had been married less than 1 year.
      > F: Strong positive correlation between male's score on Mate Retention Inventory and female's score on Spouse Influence Report. Men who used guarding (coming home early)/negative inducements (threats to kill) were more likely to use physical violence. These retention behaviours reliably predicted husbands' use of violence against their wives.
      > Further supported by Wilson et al, who found that male retention strategies left 53% of respondents fearing for their lives.
    • What is the evolutionary explanation of bullying?
      > Volk et al believed females find characteristics associated with bullying attractive as it suggests dominance, acquisition of resources, strength etc. Also prevents future competition.
      > So, bullying-related characteristics offer perfect mix of greater access to females and little threat from rival males.
      > In females, bullying more often takes place in relationship, by controlling male partner and ensuring he continues to provide resources for future offspring.
      > Bullying behaviour in both sexes can therefore be seen as adaptive.
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