Flashcards
Aggression- Key Studies
Cards in this deck (14)
- 1Aggression Key studiesPapez (1937)
Linked the limbic structure to emotional behaviours such as aggression - 2Maclean (1952) Revised the link between the limbic structures to emotional behaviours. He identified the limbic system as comprising the cingulate gyrus, septal area, hypothalamus, fornix, amygdala and parts of the hippocampus and the thalamus. the most important structure by far is the amygdala. This has a key role in humans and nonhuman animals in how an organism assessed and responds to environment threats and challengesGospic et al (2011)
Used a well-established laboratory method of assessing aggressive behaviour called the Ultimatum Game. This feature two players. The proposer money has split the money in a certain way with the Responder. If the responder accepts, the money is split as proposed. But if the responders while having their brains scanned by fMRI, which highlights activity in a different area. The researchers found that when responders rejected unfair offers scans revealed a fast and heightened response by the amygdala. They also found that a benzodiazepine drug taken before the game had two effects on responses to unfair offers. It halved the number of rejections and decreased the activity of the amygdala. This is a strong evidence of an association between reactive aggression and amygdala activity - 3Denson et al (2012) Found that normal levels of serotonin in the orbitofrontal cortex are linked with reduced firing of neurons, and this is associated with a greater degree of behaviour self-control. Decreased serotonin may well disturb this mechanism, reducing self-control and leading to an increase in impulsive behaviour including aggressionVirkkenunen et al (1994)
Compared levels of a serotonin breakdown product in the cerebrospinal fluid of violent impulsive and violent non-impulsive offenders. The levels were significantly lower in the impulsive offenders and they also suffered from more sleep irregularities. This is significant because serotonin regulates sleep patterns. Disturbance of this pattern strongly implies some disruption of serotonin functioning, further supporting the role of serotonin in reactive aggression - 4Giammanco et al (2005) Demonstrated that experimental increases in testosterone are related to greater aggressive behaviour in several speciesDolan et al (2001)
Found a positive correlation between testosterone levels and aggressive behaviours in a sample of 60 male offenders in UK maximum security hospitals. These men mostly suffered from personality disorders and had histories of impulsively violent behaviour - 5Coccaro et al (2007) Said that in patients with psychiatric disorders that prominently feature aggression, activity in the OFC is reduced, disrupting its impulsive-control function and thus leading to increased aggressionGospic et al (2011)
Outlined on the facing page this indicates that the regulation of aggression is highly complex and involves at least 3 neural structures in the brain: the amygdala, the OFC and the connection between the two - 6Berman et al (2009) Gave their participants either a placebo or a dose of paroxetine, a drug which enhances serotonin activity. Participants then took part in a laboratory-based game in which electric shocks of varying intensity were given and received in response to provocation. The paroxetine participants consistently gave fewer and less intensive shocks than those in the placebo group. However, this was only true of the participants who had a prior history of aggressive behaviourMazur (1985)
Formulated the biosocial model of Status (BMoS) to explain the link between testosterone and aggression in humans. Testosterone levels change rapidly during the course of the day, especially in response to social interactions related to status, for example, should affect post-competition aggression - 7Mehta and Josephs (2006) Measured changes in their male participants' testosterone levels before and after a competitive game (which they all lost). Once the second sample was taken, the participants were given a choice. They could either challenge their victorious opponent to another competition (aggressive) or complete another unrelated task (unaggressive). Of the losers whose testosterone levels rose after their loss, 73% rechallenged. But of the losers who testosterone levels dropped, only 22% rechallenged.Mehta and Mehta (2011)
Developed the Dual-hormone hypothesis to explain why there is mixed evidence for testosterone level on aggression. They claim that high levels of testosterone lead to aggressive behaviour only when levels of cortisol are low. When cortisol is high, testosterone's influence on aggression is blocked. Cortisol is a glucocorticoid hormone that plays a central role in the stress response - 8Popma et al (2007) Studied adolescent males and confirmed the dual-hormone hypothesis in relation to direct aggression. The combined activity of testosterone and cortisol may be a better predictor of human aggression than either hormone aloneCoccaro et al (1997)
Studied adult male monozygotic (MZ) and dizygotic (DZ) twins. Because MZ twins share 100% of their genes but DZ alone share 50% (on average, we would expect to find greater similarities in aggressive behaviour between MZ twins if aggression is mostly influenced by genetic factors. This is because both MZ and DZ twins are raised in the same environment. For aggressive behaviour defined as direct physical assault, the researchers found concordance rates of 50% for MZ twins and 19% for DZ. The corresponding figures for verbal aggression were 28% (MZ) and 7% (DZ) - 9Rhee and Waldman (2002) Carried out a meta-analysis of adoption studies of direct aggression and antisocial behaviour, a prominent feature of which is aggressive behaviour. they found that genetic influences accounted for 41% of the variance in aggression, more or less in line with findings from twin studiesBrunner et al (1993)
Studied 28 male members of a large Dutch family who were repeatedly involved in implusively aggressive violent criminal behaviours such as rape, attempted murder and physical assault. The researchers found that these men had abnormally low levels of MAOA in their brains and the low activity version of the MAOA gene - 10Stuart et al (2014) Studied 97 men who, because they had been involved in inflicting intimate partner violence (IPV), were part of a batterer treatment programme. Men with low-activity MAOA gene were found to be the most violent perpetrators of IPV. They engaged in the highest levels of physical and psychological aggression and inflicting the worst injuries on their partnerFrazzetto et al (2007)
Found an association between higher levels of antisocial aggression and the low-activity MAOA gene variant in adult males, as expected. But this was only the case in those who had experienced significant trauma during the first 15 years of life. Those who didn't experience such childhood trauma didn't have particularly high levels of aggression as adults, even if they possessed the low-activity MAOA variant. This is strong evidence of a gene-environment interaction - 11McDermott et al (2009) Showed that participants with low-activity MAOA gene behaved aggressively in a laboratory-based money-allocation game, but only when they were provoked. Otherwise, they were no more or less aggressive than other participantsVassos et al (2014)
In a meta-analysis, couldn't find any evidence of an association between a single gene and aggression. Their explanation for this result was that even several genes are unlikely to fully explain behaviour as multifaceted as aggression. In fact, they calculate that hundreds or thousands of genes interact in complex ways to determine aggressive behaviour, casting doubt over any search for a single candidate gene - 12Mertins et al (2011) studied participants with low-activity and high-activity variants of the MAOA gene in a money-distributing game. Participants had to make decisions about whether or not to contribute money for the good of the group. The researchers found that males with the high-activity variant were more co-operative and made fewer aggressive moves than the low-activity participantsGodar et al (2014)
Showed that MAOA knockout mice have significantly increased brain serotonin levels and are hyperaggressive. Furthermore, when serotonin was blocked by the drug fluoxetine, the mice reverted to their non-aggressive behaviour - 13Lea (1984) Said fixed action patterns (FAPs) have 6 main features. They are: - Stereotyped, or relatively unchanging sequences of behaviour. - Universal, because the same behaviour is found in every individual of a species - 'Ballistic', once the behaviour is triggered it follows an inevitable course and cannot be altered before it is completed - SIngle-propose, the behaviour only occurs in a specific situation and not in any other - A response to an identifiable specific sign stimulusTinbergen (1951)
Procedure
Male sticklebacks are highly territorial during the mating season and all males in this time have a red spot on their underbellies. If another male enters the territory, a FAP is initiated. The sign stimulus that triggers the innate releasing mechanism is the sight of the red spot. Tinbergen presented sticklebacks with a series of wooden models of different shapes - 14Tinbergen (1951) Findings Regardless of shape, if the model had a red spot the stickleback would aggressively display and even attack it. But if there was no red spot, there was no aggression, even if the model looked realistically like a stickleback. He also found that these aggressive FAPs were unchanging from one encounter to another. Once triggered, the FAP always ran its course to completion without any further stimulusNisbett (1993)
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- AS level Psychology Flashcards on Aggression- Key Studies, created by Benjamin Smith on 20/04/2018.
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