Aggression Flashcards
which two of the following statements are true
-aggression involved low MAOA gene activity
-MAOA gene influences levels of serotonin
MAOA gene
-determines the production of MAOA enzyme
-MAOA enzyme breaks down neurotransmitters in the brain after a nerve impulse has been transmitted from one neuron to another
-it breaks down neurotransmitters such as serotonin and dopamine
-Humans have various forms of the MAOA gene e.g MAOA-L (Warrior gene) leading to low levels of the MAOA enzyme
-low levels of this enzyme lead to abnormal levels of serotonin = more impulse and aggressive behaviour
Brunner et al
Brunner et al (1993):
-28 male members of a large dutch family involved in impulsive aggressive behaviours such as rape, attempted murder and physical assult
-found an association between MAOA deficiency and increased impulsive aggression
Twin studies
-herediability account for 50% of the variance in aggressive behaviour
-Emil Corraco et al (1997) = studied adult male MZ and DZ twins = concordance rates of aggression is 50% in MZ twins and 19% in DZ twins = physical aggression
adoption studies
-Rhee and Waldwin (2002) = carried out meta-analysis of adoption studies of direct aggression and antisocial behaviour = 41% of genetics = variance of aggression
gene-environment interactions
-low MAOA gene activity is only related to adult aggresison when combined with early life traumatic events
-Frazetto et al (2007) = found an association between higher levels of antisocial aggression and low activity of MAOA gene in adult males = diatheiss stress
strengths = genetic explanations of aggression
-research support for role of MAOA gene in aggression (empirical evidence) = Brunnert al al (1993)
-twin studies + adoption studies
-self-report method of measuring aggression
-There is evidence supporting a positive correlation between increasing MAOA activity levels and increasing levels of prosocial behaviour, as demonstrated by Mertins et al (2011) who found that participants with high MAOA activity levels behaved more compassionately in a money-lending game, often with fewer provocations or refusals of offers. Therefore, this suggests that the link between MAOA and aggression is valid because correlations in both directions (increasing and decreasing MAOA levels) are supported by research evidence.
-There is also evidence supporting the strong link between MAOA activity levels and concentrations of serotonin, which has been based upon animal studies where researchers are able to ‘switch off’ or prevent the expression of the gene coding for the MAOA enzyme, thus allowing the researchers to study its effects in isolation. For example, Godar et al (2014) found that when the MAOA gene was switched off in mice, these mice were ‘hyperaggressive’, potentially due to the increased stimulation of postsynaptic neurons due to an increased concentration of serotonin in the synaptic cleft. Therefore, alongside additional evidence that the serotonin agonist ‘fluoxetine’ reverses this effect, increases the validity of the MAOA-aggression link.
limitations = genetic explanations of aggression
-interactionism approach should be adopted
-deterministic
-gender bias = Brunner = only male + testosterone
-socially sensitive research = reduce impact of serious crimes due to genetics = make Victims harm feel inferior and unimportant
-diathesis stress
-— However, a major problem with the use of the diathesis-stress model is the difficulty in distinguishing between the effects of nature (MAOA genetic mutations) and nurture (childhood trauma), as well as determining which has a larger influence. For example, McDermott et al (2009) found that provocation in a money-lending game was key to triggering aggressive behaviour in individuals with low MAOA activity levels, whereas previously they displayed the same levels of aggression as the healthy, neurotypical control group. This suggests that although the interactionist approach may be a better explanation for aggression compared to biological determinism, there is still a lack of clarity over the role of the stressor.
aggression + reactive aggression
-Reactive aggression –> meaning they consistently overact to perceived threats
-greater activity in the amygdala is linked to fear
-lower activity in the prefrontal cortex is linked to reasoning and decision making
limbic system
-The limbic system (subcortial structures) is part of the brain involved in regulating our behavioural and emotional responses, especially when it comes to behaviours and we need for survivial; feeding, reproduction etc. The limbic system includes the hypothalamus, amygdala and parts of the hippocampus
amygdala
-the reactivity of the amygdala in humans and other mammals is an important predictor of aggression.
-the amygdala has a key role in how animals assess and respond to environmental threats. When it is stimulated electrically, animals respond with aggression
-if the amygdala is removed then animals would not long respond to things that would have caused a fight or flight response (aggression) before
Gospic et al 2011
-lab method of assessing aggression known as the ultimatium game
-involves 2 ppts where one is given money and can decide how the split between the two
-an unfair offer was seen as a provocation. If the offer was rejected this was seen as an aggressive reaction
-when ppts rejected (acted aggressively) fMRI scans showed a fast and heightened response in the amygdala
-found that benzodapine drug (Reduces arousal in the autonomic nervous system) taken before the game had 2 effects on responses to unfair answers – it halved the number of rejections (reduced aggesssion)
orbitofrontal cortex and serotonin
-OFC is the area of the brain involved with decision making and regulation of behaviour
-serotonin is a neurotransmitter that allows the communication of impulses between neurons at the synapse
-it has inhibitory effects (slows and calms neural activity)
-normal levels of serotonin in the OFC are linked with reducing firing of neurons which in turn leads to greater behavioural self control
-low levels of serotonin disrupt this mechanisms, reducing self-control and leading to an increase in impulsive behaviour
Serotonin research
Virkkunen et al 1994:
-compared levels of serotonin breakdown product in the cerebrospinal fluid of violent impulsive and violent non-impulsive offenders. The levels were significantly lower in impulsive offenders
testosterone
-Testosterone is an androgen (male sex hormone) responsible for the development of masculine features such as facial hair, muscle mass etc. Has other roles as well on male typical behaviours such as regulating sex drive and increasing libido. Also been shown to play an important role in social behaviours such as cooperation and aggressive behaviours
testosterone research
Giammanco et al 2005:
-castration studies removing testes of animals reduces aggression in many species. Giving injections of testosterone to the same animal then restores aggressive behaviour
Dolan et al 2001
Dolan et al 2001:
-evidence of the role of testosterone comes from studies of prison populations and violent offenders. Dolan found a positive correlation between testosterone levels and aggressive behaviour in a sample of 60 offenders in a UK maximum security prison. These men mostly has personality disorder such as psychopathy and histories of impulsively violent behaviours
strengths = neural to aggression
-effects of drugs on serotonin –> drugs that increase serotonin also reduce levels of aggressive behaviour. Berman et al 2009 = gave their ppts either a placebo or dose of paroxetine. Ppts then took part in a lab-based game in which electric shocks of varrying intesnity were given and received in response to provocation. However, this was only true in ppts who had a history o aggressive behaviour.
limitations = neural to aggression
Limitations – neural:
-role of other brain structures –> amygdala does not operate in isolation in determing aggression. Appears in tandem with the OFC which is not part of the limbic system. Coccaro et al 2007 = in people with psychiatric disorders OFC activity is reduced. — There may be an over-reliance on the limbic system as an explanation for aggressive behaviour. For example, the orbitofrontal cortex (OFC) may also play a significant role, due to its link with the action of serotonin, as shown above. Therefore, as suggested by Gospic et al, it may be more effective to focus on the neural connections between the OFC and the limbic system, as opposed to looking at the two in isolation.
strengths hormonal to aggression
-Testosterone is an androgen (male sex hormone) present in significantly larger concentrations in men, compared to women, and is responsible for the production of male facial characteristics and reproductive organs, being secreted from the pineal gland. There may be a link between decreased testosterone levels and decreased levels of aggressive behaviour, a positive correlation demonstrated by castration studies.
limitations hormonal to aggression
-— Carre and Mehta (2011) suggest that, through their dual-hormone hypothesis, testosterone does not work alone in determining aggression, but rather has an antagonistic relationship with the stress hormone cortisol, where increased levels of aggression are associated with increased testosterone levels but only when cortisol is low. Therefore, this implies that different hormones have different predictive values for aggression and are part of a system when developing aggressive behaviour.
ethology
-Ethology is the scientific and objective study of animal behaviour, usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionary, adaptive trait
-ethologists study aggression in non-human animals and generalise their findings to humans because they assume we are all subject to the same evolutionary forces (natural selection)
adaptive function of aggression
-describes aggression as an adaptive behaviour = contributes to an individuals survival or reproductive success and is thus subject to the forces of natural selection
why is aggression adaptive
1) aggression wins fights which leads to dominance and rising up in the hierarchy. This leads to mating rights and greater access to resources
2) A defeated animal is rarely killed and usually has to find territory somewhere else. Losers spread out over a wider area, discover new resources which reduces competition
ritualsitic aggression
-disocvered by Lorenz
-ethologists observe very little physical damage done in fights between animals. It is suggested that aggression is ritualistic
-usually involves signalling – baring teeth, threatening behaviour, voacalisation
-aggressive confrontations between animals often end is appeasement displays. These displays indicate acceptance of defeat, submissiveness and inhibit aggressive behaviour in the winner of the fight
research = ritualistic aggression
–> aggression acts as a method of increasing one’s social status within a hierarchy, as demonstrated by Pettit et al (1988) who found that young children use aggressive tactics in playgrounds to assert their authority, lead the others and have their way
-aggression increases the chance of survival of a species - through appeasement following an aggressive confrontation, the ‘loser’ will seek out new territory, increasing the scope of the resources of the species and so increasing their chances of survival
innate releasing mechanisms (IRM)
-biological structure or process in which the brain is activated by an external stimulus than in turn triggers a fixed action pattern
-aggression can be the result of an evolved automatic biological response in the brain
-animals have a built in neural structure which when exposed to specific stimuli such as teeth being shown will cause the release of an automatic behavioural response.
-animals studies are able to separate biological and social processes when studying aggressive behaviour
Fixed action pattern (FAP)
-A sequence of stereotyped pre-programmed behaviours triggered by an innate releasing mechanism
-universal = same in every individual of the species
-stereotypes = predictable and unchanging
-unaffected by learning
-ballistic = once triggered, follows its course and cant be changed before completitin
-single purpose = only used for one specific stimulus
-consequential aggressive behavioural sequence is called the FAP
-an environmental stimulus triggers the IRM which then released a specific sequence of behaviours
Stickleback research = ethological
Tinbergen (1951) - Stickleback research:
-sticklebacks highly territoral during mating seasons and develop red spot under their belly. If male enters territory, highly seterotyped sequence of behaviours aggressive initiated (FAP)
Procedure = presented wooden models with red spots and end observed reactions
Findings = regardless of shape, if a model had a red spot the other male would aggressively display and even attack. No red spot = no aggression. FAPS didn’t change from encounter once triggered he FAP always run its course.
