Aggression Flashcards
What is the limbic system ?
subcortical structures in the brain , including the hypothalamus and amygdala, thought to be closely involved in regulating, emotional behaviour ,including aggression.
what is serotonin ?
a neurotransmitter with widespread inhibitory effects throughout the brain . It has a key role in aggressive behaviour .
what is testosterone
a hormone from the androgen group that is produced mainly in the male testes (and in smaller amounts in the female ovaries ). Associated with aggresiveness.
who did the study on the limbic sytem?
James Papez and Paul Maclean linked the limbic system to emotional behaviours including aggression.
-They defined the limbic system as the HY POTHALAMUS, AMYGDALAANDPARTSOFTHEHIPPOCAMPUSandother strucuresseepage .
conclusion about the limbic system (think amygdala)
Reactivity of the amygdala in humans and in other mammals is an important predictor of aggressive behaviour (the more responsive the amygdala is the more aggressive a person is.
-So the amygdala has a key role in how mammals assess and respond to environmental threats .
Who studied the activity of the amygdala ?
Katarina Gospic , where some participants were subjected to mild provocation. When participants ,, reacted aggressively tot he fMRI scans showed by heightened response by the amygdala ,
-A BENZODIAZEPINE DRUG ( which reduced arousal of the autonomic nervous system )taken before the provocation led to two effects; it decreased the activity of the amygdala, and halved the number of rejections (reduced aggression ) illustrating again , the role of the amygdala .
Orbitofrontal cortex and serotonin part one;
serotonin is a neurotransmitter that has widespread inhibitory effects in the brain ,i.e. , it slows down and calms neuronal activity.
-Normal levels of serotonin , in the orbitofrontal cortex, are linked with reducing , firing of neurons which is associated with greater behavioural self control .
what does decreased serotonin do and then compare the levels .
decreased serotonin, deficiency disrupts this mechanism, reducing self control and leading to an increase in impulsive behaviour , including aggression.
- Matti Virkunnen compared levels of a serotonin breakdown product (a metabolite called HIAA) in the cerebrospinal fluid of violent and impulsive and non violent non impulsive of offenders . This levels were significantly lower in the impulsive offenders.
What role does testosterone play in the body .
The male sex hormone testosterone is an androgen responsible for the development of masculine features . It is thought to be linked to aggressive behaviour for several reasons.
-Many people have observed that men are generally more aggressive than women . Men become aggressive towards other men at the same time of development , after 20 years at the same time of development.
-Testosterone has a role in regulating social behaviour via its influence on certain areas of the brain implicated in aggression .
studies done for testosterone - castration studies
Giammanco, castration studies of animals show that removing the testes (the source of testosterone ) reduces aggression in males of many species . Giving injections ,more testosterone to the same animals restores aggressive behaviour Giammanco.
humans prison studies for aggression
some evidence for a similar association in humans comes from studies of prison populations , e.g , violent offenders .
Dolan found a positive correlation , between testosterone levels and aggressive behaviours example 60 offenders in uk maximum security hospitals.
-these men has personality disorders and histories of impulsive violent behaviour.
progesterone levels linked to aggression
there is some evidence that progesterone (a female ovarian hormone ) plays an important role in aggression in women .
-Levels of progesterone vary during the ovulation cycle and are the lowest just after mensuration l.
-Anna Ziomekiwix a found a negative correlation between progesterone levels and self reported aggression . Suggesting how low levels of progesterone are linked to increased aggression in women.
EVALUATION
Other brain structures
-One limitation of the limbic explanation , is more research showing that non - limbic brain structures are also involved in aggression .
-Limbic structures (e.g the amygdala , function together with the orbitofrontal cortex , which is not part of the limbic system . The OFC , is involved in impulse regulation and inhibition of aggressive behaviour .
-According to Emil Cuccaro , OFC , activity is reduced in those psychiatric disorders that feature aggression . This reduced activity disrupts the OFC;s impulse - controlled function , which in turn , causes aggressive behaviour .
-This shows that the neural regulation of aggression is more complex than theories focusing on the amygdala suggests .
Evaluation - drugs and serotonin
one strength of the serotonin explanation is research into the effects of drugs . Drugs that increase serotonin have been found to also reduce levels of aggressive behaviour Mitchell Berman , gave participants either a placebo or a dose of paroxetine .
-Then participants then took part in a lab - based game that invoked giving and receiving electric shocks in response to provocation . The paroxetine group consistently give fewer and less intense shocks than the placebo group . This is evidence of a casual link between serotonin , function and aggression .
EVALUATION EXTRA - direct or indirect
There is an argument that neural factors are directly linked with aggression , .
-This is evidence to support this view in Gospic , study of the amygdala reactivity and benzodiazepines .
-However , the role of neural factors may be indirect . For example . Thomas Denson , link between serotonin , and aggression . But this is an indirect link because other factors (Social psychological ) may influence it . ,
EVALUATION - animal research 0 strength of hormonal explanations
Support from research with non - human animals . Marco Giammanco review of studies to confirms the role of testosterone levels . For example in male Rhesus macaque monkeys there is an increase in both testosterone and levels of aggressive behaviour during the mating seasons .
-In rats , castration of males reduces testosterone and also mouse-killing behaviour , injecting female rats with testosterone increases mouse-killing . These findings show the role of testosterone in a range of animal species .
Evaluation - dual hormone hypothesis
one limitation , is mixed evidence of the link between testosterone and aggression in humans , Justin Carre and Prankal Mehta developed a dual hormone hypothesis to explain why .
-They claim , that high levels of testosterone lead to aggressive behaviour but only when levels of cortisol are low .
-When cortisol is high , testosterone influence on aggression is blocked . The hormone cortisol plays a central role in the body’s response in
Evaluation Extra
-Hormonal mechanisms, invovled in AGGRESSION IN HUMANS AND OTHER MAMMALS ARe likely to be very similar . In fact , the research on this human spread shows, that a lot of what we known, about the role of hormones comes from non-human studies .
-However aggressive behaviour in humans is more complex than in other mammals . For example , Carre and MEHTA’S findings concenrning crisol applied onlyto human aggreiosn .
-Also cogntiotive factors plahya greater role in human aggression , especially in cold-blooded poractive aggession .
genetic factor
-genes consist of DNA strands DNA produces insturctions for egernal phsycial features , of an organisms
(such as eye colour height ) , and also spepcific , phsycial features (such as neurotransmitter level and size of brain strudutres These may impact on psychological features such as intelligence and mental disorder ). Genes are transmited , from parent to offspirng i.e inherited .
MAOA genes
The genes responsiblle for the activity of the enzyme monamine oxidase in the brian . LOw activity variant of the gene is closely associated with aggresive eaviour .
Twin studies
-Several twin studies , have suggested , that heritability (i.e genetic factors ) , accounts for abount 50% , of the variance in aggresive , behaviour . For exmple , Emil , Coccaro studied , men who were either monozygotic , or digozygotic twins .
-Becausse , MZ twins , share 100% , of their genes but DZ tins , only share 50% in average we would expect to find greater similarities in aggressive behaviour between MZ twins , if aggression is mostly influenced by genetic factors .
The MAOA GENE
The MAOA , gene controls the production of an enzyme , called monoamine oxidiase A , (MAO-A note the gene is MAOA and the enzyme MAO-A) . MAO-A , regilates , the neurotransmitter serotoonin (a monamine ) . As we saw on hte previosu spread , serotonin is thought to play an important role in impulsive aggression .
MAO gene - genes contrlling
genes come in different variants (hgh and low in the case of the MAOA gene ) . The low-activity vriant (MAOA-L) , result in low acitivty og th MAOA-A enzyme (MAO-A dfeicniecy ) , It is the variant m (mAIA-L results in low aciticty of the MAOA enzyme MAOA deficencey . It is the MAOA- L variant , that has been linked to high levles of aggressive behaviour .
MOA GENE - warrior gene
MAIA gene has beeen nicknamed warrior genes because of research by Rod Lea and Geoff chamber (2007) which showed tht the MAOA-L variant was possessed by 56 % , of new zealand Maori men (compared with 34 % of caucasians ) , historically the maori , people have had a reputation for being ferocious , wwarriors hence hte nickname .
the link between MAOA-L aggression was further , cemented by Han Brunner (1933)
-Linkk between , , they studied 28 men , from a large dutch family , who were repatedly inolved , ion impulsively aggressive violent , criminal behaviours such as rape attempted murder and physical assault . These men had anormally low levels , of the enzyme MAOA- A as well as he MAOA-L gene variant (which is sometimes reerred to as the BRUNNER SYNDROME ) .
Gene - environment Gxe) INTERACTIONS
Genes are crucial infleunces on aggressiv bhaviour but they do not functions , in isolation . IT appers to be hte case that MAOA-; genes acticity , is only related to adult aggressionwhencombined with early trauamtic life experiences .
(GxE) INTERACTIONS For example
Giovanni Frzazzeto found an associaiton between higher le els of antisocials < aggression < and the MAOA_L gene varaint in men < as expected But this <w as only the cas ein those who ahd eperiences sginifican trtruama (SUCH AS SEUAL OR PHYSICLA BAUSE ) DURING THE FIRST 5 YEARS OF LIFE , tHOSE WHO HASD NOT EXPEIRENCED SUCH AS CHILDHOOD trauama did not have partiuclarly high levles of aggresion as adults ,e ven if htye possessed athe MAOA-L variant . This is strong evidenceof a geneenvironemtn ineraction (sometimes descirbed diatheiss mdoel )
EVALUATION 0 genetic factors in aggression
One strength is support for the role of the MAOA gene n aggresion .
-Research on the facing page shows that the low activity varain of the MAOA (MAOA-L gene is associated with greater aggression .
-Vanessa Mertins et al (2011) found that the converse is also true .
-Men with low activity and high activity variants of the MAOA gene took part in a money distributing game .
-Men with the higher-activity varaint (MAOA-H) were more co-opertive and amde fewer aggression moves than the low activity participants .
–This finding supports the relationship between the MAOA gene activity and aggresison .
EVALUATION - COUNTERPOINT
However , the study by Mertins et al also showed tht non-genetic factors are crucial . THey found that even participants with low - activity MAOA variant (MAOA-L) behaved co-operatively rather than aggresively when they were made ware that others in the sutdy were behaving co-operatively . (gIVING money away ) .
-KNOWLEDGE OF SOCIAL NORMS , actually partly determined how aggresive or coopertive the MAOA-L participants were . Therrefore genes are infleucned by environental factors (knowing about other’s behaviours ) that are at least as important in aggression .
EVALUATION - for genetic factors in aggression - it being a complex link (1)
-One limitation of the MAOA serotonin agression links is that the precise mechanism is unclear . On the previous spread , research linked aggression with low levels of serotonin (Virkkunen 1994) , . But the MOAA-L genes causes low activity of the MAO-A enzyme which in turn should lead to higher serotonin because the low-activity enzyme does not deactivate serotonin (its normal funciton ) , leaving more serotonin for synaptic transmission .
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evaluation - for gentic factors in aggression it beign a complex link (2)
In people witht he MAOA-L variant , it ma be more accurate to say that thier serotonin levels are disrupted rather than they are lower or highher than normal . This shows that the relationship between the MAOA gene serotonin and aggression ois not yet fully understood .
evaluaiton - genetic facotrs 0 problems with twin studies
Another limitaiton of the genetic expalantion is that twin studies ma lack validity .
in every pair of twins , both indiviudals share the same environment as each other (because each pair is raised together ) .
-However , DZ , twin may not share thier enviornment , to the sme extent tha MZ twins share theirs .
-We assume they do and this is called the equal enviornemnts assumptio n .
evaluaiton - genetic facotrs 0 problems with twin studies (2)
The assumption hwoever , may also be wrong because one aspect of the environment , is the way twins are treated by others . MZ twins are treated very similarly especially by parents (rpaising them equally for being aggressive ).
-DZS , are treated in less similar ways , thois means that concordancw e rates are inflated and geentic infleucnes on aggresion may not be as great as twin sudies suggest .
Evaluation extra - nature and nurtrue
several lines of evdienc eon this psread point ot geenes as direct causes of aggression . THese incldue twin and adoption stuies , research on the MAOA gene and animal studies .
-HOwever , there is also evidence that environmental fctors are improtant . Criticisms of twin studies , support this view , Earlyc hildhood trauma also plays a role . At the very leas environmental factors affect whether a gene is expressed or not .
What are ethological explanations
An explanation that seeks to understand the innate behavior of animals (including humans ) by studying , them in their natural environments .
Innate releasing mechanism (IRM)
A biological structure or process (e.g in the brain ) which is activated by an external stimulus that in turn triggers a fixed action pattern .
Fixed action pattern
a sequence of sterstereotypedotyped preprogrammed behaviours triggered by an innate releasing mechanism.
adaptive functions of aggression (1)
the ethological explanations suggests that the main function of aggression is adapive . Aggression is beneficial to survival becuase a defeated animal israrely killed , but rather is orced to establish territory elsewhere . This means hat memebers of a species spread out over a wider area and hve to discover resouces in a diferent place , which reduces compeition pressure and he possibility of starvaiton .
another adaptive funcitono f agression (2)
qanother adaptie fucntion of aggression is to esablish dominance hierachies . Male chimpanzees use aggression to climb their troop;s social hierchy domiannce give them special status (e.g mating rights over females ) . This happens in humans too . Gregroy Pettit studies groups of uyoung children and observed whow aggresion played an importnat role int he development of dominance hierachies . This would be adapive (and thus naturally sleected ) because dominanc eover other thing bring benefits cuch as access to resource (food and mates )
ehological expplanations of aggressio - ritualisitic aggression
a ritual is a series of behaviours carried out in a set order . Konrad Lorenz (1966) observed hat fihgths between animals of the same species porduced little actual physical damage . Most ggrssive encounters consisted of a prolonged period of ritualiitc signalling (e.g displaying clwas and teeth ,f acial expressions of threat ) .
-Furthermore , Lorenz pointed out that intra-species aggressive confrontations end withritual appeaappeasementseent displays . These indicate acceptance of defet and inhibit urther aggressive behaviour in the expose its neck to the victor , a submissive appeasement gesture making itself vulnerable to a single bite to its jugular vein . This is adptiv , because if every aggressive encounter ended with th edeath of one of the combatants that could threaten the exisence of the species . .
ritualistic aggresion (2)
-Furthermore , Lorenz pointed out that intra-species aggressive confrontations end withritual appeaappeasementseent displays . These indicate acceptance of defet and inhibit urther aggressive behaviour in the expose its neck to the victor , a submissive appeasement gesture making itself vulnerable to a single bite to its jugular vein . This is adptiv , because if every aggressive encounter ended with th edeath of one of the combatants that could threaten the exisence of the species . .
Innate releasing mechanisms and fixed action pattenrs
an innae releasing mechansims is an ibuilt phsyiological process or strucutre for instance a network of neurons (a ciruit ) in the brain . An envioronemntal stimulus (such as certain facial expression ) triggers the IRM , which then ‘releases’ a specific sequence of beaviours This behavioural sequence is called a fixed action pattern . AAccordign to Stephen Lea (1984) ,
FAOS have six main features ;:
-stereotyped or relatively unchancging sequences of behaviours .
-universal because the same behviour is found in every idnvidual of a species .
-unaffectd yb elarning ,t he same for every ivnidvidual regardless of experience .
-ballisitic once the behaviour is triggerd it follows an inevitbl course and cannot be altered before it is compelted .
-single purpose the behviour onl occurs in a specific situation and not in any other .
-a resposne to an identfiable specific isgn stimulus ( or fi it invovles communicaiton beeen memebrs of he same species it is knowna s a relaser )
tinenebrrgen’s research PROCEDURE
Male stickelbacks are hgihgly territroial during the spring mating season , when they are also develop a red spot on their underbelly . Idf another male enters thier sterritory a sequence of highly -sterotyped d aggressive behaviours is intiiaed (FAP) .
-THe sign stimulus (the particual feature of a stimulus ) that trigers the innate releasing mechanism is the sight of the red spot , NIKO tinbergen (1951_) presened sticklebcks with a series of wooden models of different hspes .
Tinbergen’s research - FINDINGS
Regardless of shape , if the mdoel had a red spot the male stickleback would aggressively display and even atttack it . BUt if there was no red spot , there was no aggression ,m even if the mdoel looked realistically like a stickleback . Tinbergen also found that these aggressice FAPS were unchanging from one encounter to another . Once triggered , the FAP , always ran its course to compeltion without any further stimulus .
EVALUAITON - etholoigcial explanations - RESEARCH SUPPORT
One strength is support from the reserch related to genetics and evolution . On the previous spred , we considered evidence that support a geentic basis for aggression . For example ,, Han Brunner showed tht one egene MAOA -L gene , is closely associated with aggressive behaviour in humans .
EVALUATION 0 RESEARCH SUPPORT (2)
Twin and adoption studies alsalsoso showed tht there is a significant genetic component to aggression in huamns . Furthermore , ont he next spread , we look at the case for seeing aggression as an adaptive behaviour (IWLSON AND DALY 1996) , and therefore , genetically-based. THese , lines of research point towards an innate basis to aggressive behavours . This suggests the ethologicl a paggression porch is correct in claiming that aggresion is genetically determined heritable and adaptive .
evaluation research support - COUNTERPOINT
However , aggressive behaviours differs from one culture to another , sometimes even within the same country . Richard Nisbet (1993) , found that one type of homicide (the result of reactive aggression ) , was common amongst white men in the southern United states , than in the northern satates .
evaluation resrach support counterpoint (2)
reactive aggression is a response to hreats from someone else . Nisbett condluconcludedded tha the difference ws caused b y a culutur e fo honour , in the southern us . This is less prevalent int he north , whcih is hwy rective ggression homicide rtes are lower there . SO this ind of aggresive beahviour comes from a learned social norm rather than being instiictive . Therefore culutculturere can overrinnateid einnate predispositions which is hard for ethological theory to explain .
ritualisitc aggression - ethological explanation one limitiation is that agression agaisnt memebers of the same species is not just ritualisitc . Jane Goodall (010)
Jane Goodall (2010) m ibserved four year war , during which male chimps rom one community killed all the members of another group . THe did this in a systematic wy . Ons ome occasions ,a vicitm would be held down by rival chcimps while others hit it inn an atack lasing many minutes .
-The violence , continued ,, even though the victims offered appeasement signlas .
-These signals did not inhibit the aggrssive behviours of the atackers as predicted by the ethological explanation . This chllenges the ethological view tht same - species aggression has evovled into a self-limiting and relatiely harmless ritual .
EVAL
EVALAUTION - FAPS re onot ficed
another limitiaiton , is tht Lorenz’s origianl view of FAPS is outdaed . He saw FAps as innate and ucnahging , But the psychologists Morton Hunt (1973) , has pointed out that FAPs are actually geatly infleunced by enviornmental factors and learning expereinces .
EVALUATION 0 FAPS ARE NOTO IFXED (2)
For isntance , an aggresisve AP , is typically made up of several behaviours in a series . tHE DURATION OF EACH BEHAIOUR varies from oone indiicdual to another and even in the same individual fromo ne encounter to another . Because they are modifiable y expiereince , man ethologists now prefer the term modal behaviour pattern to reflec tthis . THEREOFRE , pattern , of aggressive are mcuh more flexible than lorenxx thought especially in huamns .
evalaution extra - born to be aggresssive
ethologists argue that aggression is an innate insiitct . An important , implicaiton og this view , is that huumans will inevitably be agressive and fight each otheor . Lonrez argued that this inevitbility is demonstrated by FAPS .
-However ,, othe pproaches , in psychology , (the cognitivie approch ) suggests that aggression is not inevtibale because it is more under rational control thn insticintive because it is more udner rational control thn isntiinctive it is also less innate and more affectd by learning experiences than ethologists accep t.
evolutionary explanaation
an account of the changes in species over millions of years based on the idea of antrual selection - an behaviour that enhances survivial nd ultimtley successful reproduction is perpetuated .
meaning of evolutionary explanations of human aggression - evolutionary explanation of sexual jealousy
sexual jealousy is a major motivator of aggressive behaviour in males which can be given an evolutionay expalantions .
-Jealousy occurs because men , unlike women , can never be totally sure about whether or not they are thier child;s parent .
-This paternity uncertainity is a result of the very real threat fofr the male of cuckoldry ( having to raise offspring that is not his own ).
evolutionayr explanaitons of jealousy (2)
any investement in offspring who do not share the male’s genes is a wste of his resources . It contributes to survival of a rival’s genes and leces the ‘father; with fewer resources to invest in his own future offsprring .
