Aggression 2

8/2/2019 Aggression 2

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Importation modelIrwin & Cressey

claims inmates who enter prison w/certain characteristics

(e.g. values, attitudes & experiences)

are more likely to engage in interpersonal violence than other inmates.

Interpersonal violence in prisons isnt aproduct of the institution,

but the charac.s of individuals who enter.

US research showsBlack inmates compared w/Whites,

are more likely to be associated w/interpersonal violence.

An explanation is:

blackprisoners often enter prison from more

impoverished communities

w/higher violent crime rates.

Thus, they import into the prison the cultural norms

that condone violent behaviour.

Institutional aggression refers to

- violent behaviourthat exists within some institutions & groups.

- & also to forms of collective violence between social groups.

Institutions may be distinct (e.g. sch, prison) or larger bodies (police, army).

Acts range from physical abuse in initiation tests, to acts to destroy a national, racial or religious

group (genocide).

Resultantly, inst. aggression involves more complex psychological processes than interpersonal

aggression & may have more traumatic consequences for victims.

Discuss 2 explanations of institutional aggression

Institutional aggression in prisons

High statistics in England & Wales show prisons are violent for both inmates & workers.

2 models are proposed importation & deprivation, to explain why interpersonal violence occurs so

regularly in prisons.

Youngerinmates have more difficulty adjusting to prison

and so are more likely to have confrontations w/inmates & staff.

Theyre also more likely to view violence as an appropriate response to

conflict.

This assumptions confirmed in a no. ofstudies (e.g. Adams).


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Deprivation model

claims its the features of the prison rather than of inmates that accounts for prison violence.

It argues its mainly the experience of imprisonment

that causes inmates high stress & frustrationwhich leads to violence + aggression against inmates

and staff.

Harer et al describe how inmate behaviour is a response to problems of adjustment posed by

the deprivations orpains ofimprisonment.

Sykes says these pains include the

- loss of freedom & ofheterosexual relationships

- isolation from the free community

- boredom, discomfort + loneliness.

As inmates endure pains, they engage in interpersonal violence

as a reaction to the hurt felt.

For example,

overcrowding in UK prisons forced many inmates

to share cells

and is linked to an increase in

- interpersonal violence,

- self-harming and suicides.

Violence is common in crowded prisons

as the conditions exacerbate tensions

among inmates, & between inmates and staff.


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Evaluation of institutional aggression in prisons

Research support for the importation model

Harer analysed data from 58 US prisons and found:

Black inmates showed more violent

behaviour

They concluded it

reflected racial diffs in these behaviours within US society generally,

supporting the claim that characteristics are imported intoprison.

Keller & Wang also found violence more likely in facilities

holding the most troublesome inmates.

E.g. prisons w/maximum-security inmates had more assaults on staff,

than prisons w/lower-security inmates.

Limitations of the importation model

McCorkle et al. claim this model fails to suggest how to

reduce prison violence in general.

The importation model also predicts membership of a violent gang

prior to imprisonment results in more violence inprison,

as gang members import gang involvement into prison.

but lower rates ofalcoholand drug abuse compared to

whites inmates.

However, DeLisis study of over800 male inmates found

no evidence

- that gang membership prior to prison

- had anybearing on violence within theprison.


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Research support for the deprivation model

Although some studies support the dep. model of prison violence,

McCorkles large study failed to support it.

The sample of371 US state prisons found

little evidence

to support the linkbetween

violence and measures like overcrowding and living conditions.

Limitations of the deprivation model

McCorkle points out that:

levels of stress associated w/imprisonment

(e.g. loss of freedom, overcrowding) are generally constant,

whereas serious outbreaks of violence e.g. in prison riots, are not.

Challenging the dep. model is the finding that among:

juvenile offendersin 4 diff. prisons,pre-institutional violence was the best predictor ofinmate aggression,

regardless of the features of the prison(Pole & Regoli)This supports the importation model

Real-life relevance

Zimbardo claims the same social psych. processes found in the prison study

also occurred in the abuse of Iraqi prisoners at Abu Ghraib prison in Iraq.

These included:

- deindividuation,- dehumanization,

- group conformity and lack of supervision,

which led to a diminished sense of accountability from the guards responsible for the abuse.

stress

imprisonment

Violentoutbreaks

imprisonment

They claim serious violence is more of a

consequence of the managementof prisons

ratherthan the general deprivation allprisoners endure.


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Institutional aggression in initiation rituals

Initiation rituals are for new members of a gp.

.

In the US, hazing, (painful rituals)formales is done to symbolically take away

the weakness ofchildhood

and replace it w/the confidence of adulthood.

(Raphael)

Raphael suggests if initiates tackle extreme initiation,

they know they can handle the rest.

Its based on a belief of what it takes to be a real man,

w/an emphasis on

- physical and mental toughness

- and obedience to superiors.

As a result, hazing occurs in the military.

In the Russian Army,a violent ritual involves nightly beatings

from drill sergeants.

However, a high-profile incident in which:

aprivate was forced to sit on a block of ice for4 hrsending w/the amputationof his leg,

prompted investigation into this practice.

Rituals can bepainfuland mentallystressful

1 function is to create a common bond

among members of a gp.

new recruits feelpart of a select gp

whose members have endured the

same extreme rituals


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Evaluation of initiation rituals explanation

Research support

Many studies found evidence of the use of initiation rituals

- to establish dominance

- and initiate newcomers in institutions

e.g. colleges, the police and military.

McCorkle found in prisons,

domination oftheweakin initiation rituals

was seen by inmates as essential to maintaining status.

Why is Hazing so effective?

Festingerscognitive dissonance theory

explains the effectiveness of Hazing.

In hazing, those who endure apainful ritual,

will feel uncomfortable cognitive dissonance

b/c the action conflicts (is dissonant) w/thebelief.

When the initiate reflects

an attitude change to reduce dissonance

is likely to occur,

and the initiate will come to value the experience.

In this way, the value of group membership,

and the degree ofsuffering endured during initiation

becomes related to the value they place on the ritual and on being a gp member (Davis).

while believing its

pointless/wrong,


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Neurotransmitters

Are chemicals that allow impulses to be transmitted from 1 brain area to another.

Therefore, all behaviours are influenced by the action ofneurotransmitters.

Aggression in animals and humans has been associatedwith:

- low serotonin

+

- highdopamine levels

Serotonin and aggression

Studies show normal serotonin levels inhibit neural firing in the brain (Cases).

So its claimed:

- low brain serotoninmake people less able to control theirimpulsive + aggressiveresponses.

Research support shows the majormetabolite (waste product)of serotonin

tends to be low in the cerebrospinal fluid

ofaggressive people. (Brown)

Also, Mann administered drug dexfenfluramine (Redux) to 35 healthy adults.it depletesbrain serotonin.

he used a Q. to assess aggression levels,

and found

- among males

- aggression levels increased after given the drug.

Dopamine and aggression

Evidence suggests

- increased dopamine activity (e.g. via amphetamine use)

- increases aggressive behaviour(Lavine).

Similarly, the use ofdopamineantagonists

have been used to reduceaggressive behaviour in violent delinquents (Buitelaar)

Dopamines released in response to rewarding stimuli

e.g. food, sex.

Couppis found evidence dopamine reinforcesaggression.

Their research suggests some intentionally seek out aggressive encounters

b/c of rewarding sensations, caused by the increase in dopamine.


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Evaluation of neural mechanisms in aggression

Serotonin alternative explanations

Its possible aggression

- isnt caused by low brain serotonin,

- but by low serotonin metabolism which leads toincreased serotonin receptors.

E.g. Arora and Meltzer found a relationship between:

Influence of serotonin on aggression may explain the relation between alcohol & aggression

Badawy found

- acute alcohol intakeDEPLETEDserotonin levels

in normal individuals,

- + in susceptible people,

this depletion may induce aggressive behaviour.

Research support

Ferrari et al support the influence ofserotonin + dopamine in aggression

They let a ratfight for 10 days at the same time.

On the 11th day, it wasnt allowed,

but researchers found that in anticipation of a fight the rats

- dopamine levels increased

- and serotonindecreased although it didnt fight.

This shows the experiencechanged the animals brain chemistry,

gearing it for a fight by altering levels ofserotonin and dopamine

in ways considered w/the onset ofaggressivebehaviour.

Difficult to demonstrate experimentally a link between dopamine + aggression?

Studies w/mice (e.g. Couppis) show the problem.

.

So its difficult to explain the drop in aggressivebehaviour,

which could be eitherdue to a

- lack of motivation to be aggressive

- or s m c m ce n t ar to mo e an ence ar to res on a ress e .

violent

suicide

and elevated serotonin receptor

density in the pre-frontal cortex.

Similarly, Mann found:

among suicide completers those

w/increased

pre-frontal cortex serotonin

receptors

chose more violentsuicidemethods.

Lowering dopamine in theirbrain

makes it hard for it to move


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sssHormonessss(e.g. testosterone, cortisol) are chemicals that regulate and control

bodily functions.

Testosteronemakes it more likelyaggressive behaviourwill be expressed.

Aggression is also influenced by factors such asprevious experience.

Research findings include:

- Books meta-analysis of 45 studies that found a

mean +ive correlation of0.14 between T & A

- Olweus compared samples ofinstitutionalized delinquent boys

and non-delinquent male students.

Delinquents w/violent crime records had higher testosterone than those of non-violent offences,

but the difference wasnt statistically significant.

However, researchers did find adolescents w/higher testosterone likelier to respond more vigorously tochallenges from teachers and peers.

And research shows higher testosterone is associated w/dominant behaviourthats rarely aggressive

(intent to injure another)

most dominant behaviours just intend to gain ormaintain status (Booth et al).

E.g.

Kouris double-blind study showed

- Ps on testosterone rather than theplacebo

- pushed abutton sig. more times, to reduce cash received by the other person.

Evaluation:

This experimental study enables us to claim testosterone can CAUSEaggressively dominant behaviour.

Testosterone and aggression

Evaluation

The positive influence of testosterone

However, in many older males (e.g. weightlifters) testosterone supplements have been positive and found

to enhance vigour and energy (Zitzmann).

Also, Barrett-Connor found depression increased w/age (50-89 yrs)

and this associated w/lower testosterone.

In a study of208 men w/testosterone deficiency,

increased positive mood with testosterone replacement therapy was confirmed. (McNicholas)


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Inconsistent evidence on testosterone + aggression

Although some studies found testosterone positively correlates w/high aggression,

otherstudies found no such link.

E.g. Bain et al found no sig. differences in testosterone levels between

- men charged w/murder,

- & men charged w/non-violent burglary.

Kreuz + Rose also found:

- no difference in testosterone levels in 21 young prisoners classed as fighting ornon-fighting.

However,

- the 10 prisoners w/histories of more violent crimes had sig. higher testosterone

- than the 11 prisoners w/o such a history.

This suggests in a populationpredisposed to violent behavioure.g. by social factors to dvp antisocial behaviour,

testosterone may be an additional factor that puts individuals at riskforviolent behaviour.


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sssCortisol and aggressionsss

Van Goozen claims an inverse correlation, where

lower cortisol is associated w/higher aggressive behaviour.

Studies report low cortisol in violent offenders and aggressive schoolchildren.

Reasons are:

1. Low ANS arousal (so low cortisol) is unpleasant;

aggressive behaviour attempts to create stress

which provokes ANS activation and cortisol release.

2. Cortisol inhibits the chance of aggressive behaviour.

Popmas study found a sig. positive relation between testosterone and overt aggression in Ps w/low

cortisol but not in those w/high cortisol.

Evaluation

Longitudinal studies provide support

e.g. McBurnett studied 38 boys in a clinic forproblem behaviours.

behaviours were evaluated annually for4 years.

They found:

boys w/lower cortisol showed 3 times moreaggressive symptoms

thanboys with higher cortisol.

They were also named the mostaggressiveby peers,

3 times as often as boys who had higher cortisol.

Lack of consistent research evidence

Many studies found:

no significant differences in cortisol betweenaggressive samples and controls.

c

aggression

testosterone

aggression

Low cortisol

testosterone

aggression

High cortisol

- Some studies (e.g. Gerra et al) even reported

higher cortisolin Ps w/higher aggression levels.


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sssThe role of genetic factors in aggressive behavioursss

Twin studies

Aggressive behaviour is higher correlated in identical (MZ) than fraternal twins.

E.g. McGuffin found a concordance rate of

- 87% for aggressive behaviour for identical twins,

- & 72% forDZ twins.

This finding supports genetics, + indicates the environment siblings share, influences juvenile

delinquency.

but the effects of each on aggression must be disentangled.

Masons meta-analysis of12 twin studies concluded

- Genetics may account for50% of the diff between antisocial and non-antisocial behaviours

- w/larger estimates found forviolent behaviours.

Coccaros twin study estimated from data on 187 identical and 118 fraternal twins:

- genes accounted for40% ofindividual differences in aggression

- environmental influences for50% ofindividual differences in physical aggression,

and 70% of individual differences in verbal aggression.

Adoption studies

If more similarity in aggression levels between adopted children and biologicalparents than w/their

adoptive parents, this suggestsgenetic influence.

But if children are more similarto adoptiveparents, this suggests environmentalinfluences are more

important in the development ofaggressive behaviour.

Danish adoptive study Hutchings + Mednick reviewed over 14,000 adoptions in Denmark.

They found a sig. positive correlation between the no. ofconvictions for criminal violence among the

biological parents (esp. fathers) and among theiradopted sons.

Meta-analysis of24 twin and adoption studies

Miles + Carey found a strong genetic influence, accounting for50% of the variance in aggression.

Although they found both genes and family environment influenced aggression in young people,

at later stages- the influence of the rearing environmentdecreased

- & the influence ofgenesincreased.


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Meta-analysis of twin + adoption studies Rhee & Waidman

Rhee + Waidmansmeta-analysis of 51 twin & adoption studies w/over 87 000 people.

calculated the contribution to antisocialbehaviour was approx.

- 40% genetic,

- 60% environmental

They found little evidence of gender diffs in the data.

Evaluation of research method

reporting aggression

the studies in the meta-analysis used self-report, or reportsby others of the Ps aggression levels.

genetic influence was assessed at 39%w/self-report, and 53% when assessed by anotherperson.

This suggests the method of assessing aggression plays an important moderating role in estimates of

genetic influences.

Imperfect nature of twin studies

MZ identical twins share genes, but also an environment that treats them more similarly than DZ twins.

B/c they look alike, society tends to treat MZ twins as 1 person.

So twin studiesarent the perfectgenetics VS environmentexperiment.

Gender differences in heritability

Buttons study of258 twins aged 11-18,

found genetics influence both aggressive and non-aggressive behaviour.

But heritability of aggressive behaviour was sig. higher in GIRLS,these results suggest a stronger genetic effect on aggression in females than in males.

Problems w/the interpretation of adoption studies

Adoption studies have methodological problems which limit conclusions that can be drawn.

1. Fergusson maintains that in some countries, e.g. New Zealand

- foster children & theirparents show more antisocial behaviour (inc. agg) at the time of their

adoption,

compared w/the general population & adoptive parents.

So correlations between adoptees + theirbiological parents may be due to eitherthe

- inherited antisocial genesfrom parents- or to environmental influences,

such as theparents antisocial behaviour(before adoption)

or from feelings ofabandonment.

sssEvaluation of twin + adoption studiessss


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sssGenes for aggressionsssResearchers identified candidate genesthat contribute to increasedriskofantisocialbehaviour.

These studies examine whether1 variant of a candidate gene occurs more oftenin people who display aggressive behaviour than in a comparison group.

Research found dysfunctions ofdopamine may increaseaggressive behaviour.

A meta-analysis found an association between:

- DRD4 (gene for dop. receptor D4)

- and a tendency to ADHD (Fararone).

Retzs study found an association between a DRD3 variant (the gene for dopamine receptor D3) and both

impulsivity and ADHD-related symptoms in violent offenders.

Candidate gene forMAOA

Also, researchers found the gene that makes enzyme MAOA may be associated w/aggressive behaviour.

MAOA enzymesbreak down3 neurotransmittersin thebrain inc. Noradrenaline.

Imbalances ofserotonin and dopamine are found inpatients w/high aggression.

Violent Male Ps in Brunners study had v low levels of MAOA, + so high levels of all 3neurotransmitters a finding that doubtslow serotonin is associated w/increasedaggression.

A defect in the gene for MAOA was lateridentified in the violentmembers of this family;

this was absent in non-violent members.

Genes for aggression do not predict aggressive behaviour -

Morley + Hall argue- genes associated w/aggression are not deterministic

- + onlypoorly predict the chance a person will display higherlevels ofaggressive behaviour

than the general population.

Also, the environmental risk factorscannot be identifiedby a genetic test, thus making the accurate

prediction of specific behaviours even less likely.

Positive implications of genetic research

Morley + Hall suggest info from genetic studies may be used to help develop new treatments forpersonality disorderidentified as risk factors forcriminal behaviour.

However, consequences of such genetic tests may include findings being cited as evidence of a defendants

diminished responsibility in criminal cases.

Gene-environment interaction

Rather than either alone, some researchers believe interactionsbetween genes + environment influence

aggression.

E.g. Caspi found male children whod been maltreated and had the gene that increased MAOA activitywere less likely to express violent behaviour.

Normally, an increase in MAOA would decrease serotonin (so increase aggressive behaviour).

But Capsi believes early abuse may alterserotonin ordecreases in serotoninaffect some antisocial

behaviours but not others.

Evaluation of genes for aggression

Candidate genes: DRD4 and DRD3


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sssDescribe + Evaluate 2 evolutionary explanations of

aggressionsss

Infidelity and jealousy

Daly + Wilson claim menevolved mate-retention strategies to detertheirmate

from leaving orcheating b/c

W/o a mate, the chance ofpassing his genes on is reduced.

So these strategies enhancereproductive fitness (surviving + passing genes).

They include:

- vigilance (e.g. mate guarding) and violence to deter infidelity.

1 is direct guarding restricting her freedom to prevent males gaining access.

E.g. stopping partners speaking w/other men.

Cuckoldry and sexual jealousy

Cuckoldry occurs when a woman deceivespartnerinto investing in another mans offspring.

Cuckolded menrisklosing invested resources & reproductive opportunity.

Males evolved mate-retention strategies topreventbeing cuckolded.

Theyre driven by sexual jealousy, an adaptation evolved in males to deal w/paternal

uncertainty.

Sexualjealousyprevents the femalemating w/others, so its an adaptive response.

The cuckoldry risk hypothesis predictsmales may use sexually coercivetactics

e.g. partnerrape when risk ofcuckoldry is high e.g. suspecting infidelity.

Lalumiere argues some men carry out partner rape to decreasepaternal uncertainty.

Thornhill + Thornhill argue a woman who resistssex w/herpartnermay signal infidelity, thus

increasing the males sexualjealousy and fear of cuckoldry.

Mate retention and violence

Buss examined mate-retention in married couples + found:

men used more debasement (e.g. giving in to her every wish)

+ intra-sexual threats (threatening to beat other man).

But women used verbal possession hes taken

& threats ofpunishing infidelity (leaving her man if unfaithful).

Mate retention + violence against women

Shackelford studied 461 men and 560 women from US unis

all Ps in committed, heterosexual relationships.

They found in study 1 that:

mens 2 types ofmate-retention strategiespositively correlatedw/theirviolencescores.

1. intersexual negative inducements (e.g. shouting at her for looking at a man)

2. direct guarding (e.g. controlling her time at a party)


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In study 2 they found that:

- results confirmed the validity offindings from study 1, w/reports of intersexual

-ive inducements + direct guarding associated w/female-directed violence.

- women also statedpartners who used emotional manipulation were more likely to have used

violence against them.

Evaluation

A limitation is data was correlational, they didnt establish a casual link between

- the use of mate-retention strategies

- and violence against women.

Lack of information another limitation of research is it

doesnt control foractual relationship threats (e.g. a mans suspicion or knowledge of hispartners infidelities).

Evaluation of infidelity + jealousy as explanations for aggression

Use of mate-retention tactics

Sexual jealousy is supported by studies of battered women, where victims cite extreme s.jealousy of

partners as the majorcause ofviolence against them.

(Dobash)

Wilsons study found evidence ofdirect guarding as mate-retention:

in women reportingpartners used this tactic (e.g. not allowing to talk to other men)

72% required medical attention after an assaultby theirpartner.

Practical applications of research

Mate-retention tactics may be indicators ofpotential violence against apartner.

The use of tactics can alert friends + family ofpotential future violence in relationships.

So relationship counselling may be used before the situation escalates intophysical violence.

Research supports sexual coercion

by male partners is an adaptive response to risk ofinfidelity.

Camilleri found:

- the risk of a partners infidelity

- predicted the chance of sexual coercion in men but not women.

Supports the adaptive explanation, as its men at risk of cuckoldry, not women.

Goetz also found- men who sexually coerced partners were more likely to report thinking partners were unfaithful.

- women reporting coercion were more likely to admit infidelity.


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The evolution of murder

Murder as an adaptive response

Buss & Duntley propose:

- humans have adaptations (i.e. characs for survival)

- that evolved by natural selection to produce murder.

and for ourancestors, murdersolved adaptive problems such as:

preventing harm e.g. injury, rape or killing of the person, their family, matesby others.

Reputation management e.g. avoidingbeing seen as easilyinjured, raped or killed.

Protecting resources e.g. shelter +food.

Predisposing factors for murder

Daly + Wilsonnoted males + females murder fordiff reasons.

Men more likely to killmen

- seen as sexual rivals

- or who challenge theirposition in the dominance

hierarchy.

But women are likelier to kill in self-defence

e.g. murdering abusive male sexualpartners.

& murders were age related, peaking formalesearly 20s

peak years ofreproductive competition.

Research suggests these are common factors in the competition for reproductive status:

Sexual jealousy cause ofsame-sex aggression + murder.

B/c ofinfidelity and cuckoldry, men are both killers + victims.

Daly + Wilson got data from 8 studies ofsame-sex killings involving lovetrianglesThey found

- 92% ofmurders involved males killing males- & only 8% offemaleskilling anotherfemale.

Lack of resources

(research on sexual selection shows females prefer males w/resources.)

Daly + Wilson suggest

- a lackof resourcesincreases male-male competition and risk of murder.

- They cite murder statistics in Detroit, showing

43% of male victims and 41% male killers were unemployed,

although the overall unemployment rate for adult males was 11%.


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Adaptive explanations for lynch mobs

At least 2805 lynched from 1882 1930 in US southern states by a hate-driven white mob (Tolnay +

Beck).

Most African-American males.Obscure reasons included demanding respect & being disreputable.

Evolutionary explanations for the behaviour of lynch mobs are:

- the power-threat hypothesis

- dehumanization of the victim

The power-threat hypothesis

Blalocksuggests as minority groups grow, majority gps try harder to maintain dominance.

Power-threat is a fear of the minoritysPOLITICAL power,

E.g. Tolnay + Beckfound reasons forlynchings included trying to vote& voting wrong party.

This fear of Negro power meant White mobs used LYNCH LAW as social control,

E.g. afterslavery was abolished,

when the social transition left the White community feeling at risk.

Ridley suggests group displays of discrimination against outsiders are more likely

when groups feel at risk.

Lynch mobs and dehumanization

Hyatt argues that bydefiling the Black body in lynching +burnings, the mob reduced it to aform unrecognizable as a human.

Tolnay suggested PROPOGANDA- reducedBlacks to simplistic animalistic stereotypes to whites,

- that dehumanized victims to a worthless hated object.

encouraging lynch mobs actions b/c they were

- defending theircommunity from blackbrutality.

So lynching can be seen as an evolved adaptation to perceived threats.Lynch mobs & deindividuation

However, Mullen analysed 60 newspaper reports oflynchings + found:

- As the mob size increased, lynchers became more violent.

Consistent w/deindividuation, the increases in mob size broke down normal self-regulation processes,

increasingviolence against the victim.

sssEvolutionary explanations of group display in

humanssss - lynch mobs a group illegally kill a person for a presumed offence. Self-directed aggression during religious + cultural displays signals commitment in a gp.


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Evaluation of adaptive explanations for lynch mobs

The power-threat hypothesis

Clarkstudied lynch mob murders in Brazil, evidence contradictedpower-threat hypothesis.

Main victim Afro-Brazilians, wereNOT SEENas threats,- political or economic, to the dominant community.

Consequently, fear of minority wasnt a causal factor in these ritual murders.

Evidence for dehumanization

In Guatemala,

lynch mob violence became common in recent yrs.

Rothenberg observes although most cases are for

- crimes like murder,

- some are for minor offences like stealing chickens.

Consistent w/dehumanization,

- enraged crowds burn corpses, furtherdegrading a dead victim.

making it easier to kill by removing moral constraints on killing humans.

By reducing victims to status of animals,killing rivals becomes easier, ultimately beneficial to group members.

Role of deindividuation

Theres support for claim that lynching:

- may be a group display of extreme discrimination

- made more likely through deindividuation.

Rothenberg says however, although some lynchings were -

- at night, (where violence obscured by darkness)

- most occurred in the day.

In some cases only a few angry citizens present, whereas in others there were 1000s.

Although some aspects ofdeindividuation (e.g. large mob size) in the majority of cases,

there appears to be no clear relationship between

- deindividuating factors

- + the ferocity of violence.


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Religious displays and cooperative gains

Irons argues the adaptive advantage of living in groups wasbenefitseach person gained through cooperation

e.g. in hunting,food sharinganddefence.

In painful rituals like self-flagellation (Ashura),

a person signals commitment to a gp.

A committed member is likely to be cooperative.

So, b/c painful ritualspromote cooperation within a gp,

natural selection would have favoured their development.

COSTLY SIGNALLING to deter free riders

The costs (e.g. to physical health) of cultural and religious displays deter

- potential free riders wholl exploit gp membership w/o contributing.

Zahavi says costly signalling rituals indicate status + breeding potentialb/c theyre too costly for low quality individuals to perform.

Sosi exemplifies Ultra-Orthodox Jews (Haredim).

who overdress in summers.In their

- thick beards

- long black coats & heavy hats

Haredi men spend dayssweating as they sing praises to God.Thus, the quality these men signal is their level ofcommitment to their religious gp.

So the adaptive benefit of religious displays appears to be

- promoting cooperation within a gp,

- while deterring free riders who may exploit the gp.

Evaluation of the adaptive explanation ofreligious/cultural displays

Religious displays

Ruffle + Sosis studied Israeli communes and found religiousmales sig more cooperativew/gp

membersthan females.

Perhaps b/c

Males do highly visible rituals e.g. public prayer 3 times daily.

- They found synagogue attendance positively correlated

w/cooperative behaviour in males.

- And no correlation between s. attendance and cooperation from females, who its

OPTIONAL for, so it isnt a sign of commitment to the gp.

These RESULTS AGREE w/COSTLY SIGNALLING THEORY:

more displays of commitment positively relate w/higher cooperation within the gp.

sssAdaptive explanations for religious/cultural displays(describe + evaluate 2 evolutionary reasons for displays of aggressive behaviour)sss


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In societies where internal warfare was the norm,communities alwaysbreak up + fuse, so an ally may become an enemy.

So males are less willing to commit to permanent displays ofgp allegiance

but instead engage in temporary displays e.g. body painting.

Sosis results showed a positive correlation between

- external warfare

- andpermanentbadges of gp membership,

which supports hypothesis that costlymaleritualsevolved to

- signal commitment +- promote solidarity among males who must cooperate in warfare.

Evaluation of the adaptive explanation of religious/cultural displays

The evolutionary approach

The adaptive value ofreligious displays explains the success of some religions.

By making membership costly, they

- increaseintragp solidarity and

- deter outsiders from exploiting benefits of membership.

However, this view also suggests

- a disadvantage is it accentuates intergroup conflict.

Sosis claims the big benefit ofintragroup solidarity is:

- unified gps can defend & compete against other gps.

E.g. societies w/stricter religious displays endure more intergroup conflict. (Roes & Raymond).

Cultural rituals

Sosis had data from 60 diff societies

- on costs ofgp rituals

- and frequency of warfare.

freq. of warfare was the strongest predictor

of the costliness of the societys maleritual displays.

& displays favoured, depended on the warfarecommon in the society.

In societies where extreme warfare was more common (i.e. war against other societies)gps focused on uniting males into the largest combat gp possible.

For these societies, permanent, costly displays of gp commitment

(e.g. scars, tattoos)

reduce the chance ofmales escaping to another group.


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Aggression 2

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Transcript of Aggression 2