AGGRESSIONAGGRESSION‘hurting others’‘hurting others’

Lesson objectives

• To introduce some of the key issues in the psychology of aggression

• To consider some of the higher level skills required for A2 and how to develop them through your study of aggression

• Set your own personal learning targets

Video clip• Watch the video clip from “A history of

Violence”

• Look at the aggression shown in the film are there different types of aggression? – make a list if you think there are.

• Are there different motives or reasons for the aggression? Write down what you think.

• Is any of the aggression justified or instinctive? http://www.youtube.com/watch?v=74FdnDxptH4

AO1: Outline definitions of aggression & types of aggression

What is Aggression? Aggression:“An act carried out with the intention to harm

another person” (harm can be physical or psychological)

Aggression can be Direct or Indirect (give an example of indirect aggression from the film)

Violence: behaviour designed to cause physical injury or damage you cannot be aggressive to an object

But you can be violent!

Hostile aggression

• Aggression driven by anger & performed as an end in itself (affective aggression).

• Goal---to harm another for the sake of getting even with them.

• Characterized by displays of rage (screaming, shouting, crimes of passion) 

give an example from the clip

Instrumental Aggression• Serves as a means to an end.

Goal here—aggression is carried out to solve a problem.

• This is cool, detached, & often premediated- e.g., military, mafiahttp

://www.youtube.com/watch?v=__kf7TljgGs

Most murders are hostile aggression.

• 50% erupt from arguments while others result from romantic triangles or brawls, while under the influence of alcohol or narcotics.

• Such murders are impulsive, emotional, & volatile outbursts.

Types of Aggression

Physical Verbal

Active

Passive

HittingName

Calling

Angry looks

Gossiping

Which of the following are examples of aggression?

• Use your show-me boards

• If you think example falls under the definition aggression write ‘A’

• If you think example does not fall under the definition of aggression write ‘N/A’

Soldier shooting an enemy

Prison wardens executing a prisoner

Someone knocks over a window box Which falls and injures a passer-by

Angry child kicks and hits a chair.

Couple are tussling with one another.The ‘victim’ laughs!

A person mentally rehearses a planned murder

A driver gets drunk and knocks over a pedestrian

A father attacks someone who has abused his child

A person at a party gossips in a

disparaging way about someone.

A lion brings down a gazelle

Activity “Aggressive Behaviour”

• Work in small groups/pairs to discuss each example and for each example say what might explain the aggressive behaviour.

• What do they have in common?

• What makes them different to each other?Hint: Think in terms of direct or indirect, hostile or

instrumental, active or passive, physical or verbal?

Theories of Aggression Social Explanations

Is aggression learned? Watch the following clip and decide if it is a true representation of why children behave this way.

Thorndike's law of effect states that responses to a situation which are followed by a rewarding state of affairs will be strengthened and become

habitual responses to that situation. (make a note of this!)

What other explanations could there be for the behaviour seen?

Is it all due to learning?

LO: Outline & evaluate explanations of aggression

Albert Bandura and his colleagues at Stanford University conducted an experiment to show this effect in 1965 (The Bobo doll experiment).

http://www.youtube.com/watch?v=lCETgT_Xfzg

Bandura Ross Ross Albert Bandura and his colleagues at Stanford University

conducted an experiment in 1965. They show preschoolers a short film of a person beating

up a bobo doll. They were shown the short film twice, but there were three different endings watched by three different groups of children.

Consequence 1: model-rewarded conditionThe consequence of this ending is that after the person beating up the bobo doll, the person is rewarded with candy.Result: The preschoolers were sent to this room filled with toys. They acted violently towards the bobo doll and get rewarded at the end.

Bandura Ross Ross (cont…)

• Consequence 2: model-punished conditionThe consequence of this ending is that after the person beating up the bobo doll, the person is scolded and spanked.Result: The preschoolers were sent to a room filled with toys. At first they acted non-violently towards the bobo doll but after they saw the others get rewarded at the end, they too started acting violently towards the bobo doll. They tend to hide they violent behaviour.

• Consequence 3: no-consequences conditionHere, the preschoolers didn’t watch any consequence after beating up the bobo doll. Result: The preschoolers were sent to a room filled with toys. They acted violently towards the bobo doll. They imitated the preschoolers which watched the first consequence. This suggested that a mere exposure to TV violence ,whether or not the violence was visibly rewarded on screen, could spur aggressive responses in young children.

Theories of Aggression

Social Learning Theory (Bandura 1977): the theory that much social behaviour is learned through observing and imitating others. This theory states that human aggression is largely learned by watching other people behave aggressively, either in person or in films. It is also learned through us being rewarded and reinforced for aggressive behaviour either directly or indirectly by vicarious reinforcement.

Social learning theorists believe that personality is the sum of all the ways that we have learned to act, think, and feel.

Aggressive behaviours therefore are learned by observing others or through direct experience involving reward or punishment.

1. Social Learning Theory (SLT)

Social Learning Theory...explained - Media effects are explained in terms of imitating behaviour

seen in the media- People can learn from observing the behaviour of others, and observing the outcomes of that behaviour. Children and adults acquire attitudes, emotional responses, and new styles of conduct through filmed and televised modelling (Albert Bandura)- Good examples of this theory are television commercials that suggest that drinking a particular beverage or using a specific shampoo will make a person popular and admired. Therefore if violence or aggression on film is associated with fame, fortune or a particular famous and desirable actor e.g. Matt Damon, Tom Cruise, Daniel Craig etc, then the behaviour is more likely to be imitated.

Key Terms: • Observational learning: This is where viewers learn behaviours from

watching others and may imitate them; many behaviours are learned from the media

• Models: A model is a person who is observed and/or imitated.

Bandura (1977) suggested there are four steps in the modelling process. A.R.R.R.M.

(the long arm of aggression!)

• Attention: If person is prestigious will pay more attention. We pay attention to role models.

• Retention: Actions are remembered.

• Reproduction: We reproduce what we remember. Though vicarious reinforcement is not enough, imitation requires skill.

• Reinforcement: Actions are then reinforced either negatively or positively i.e. rewarded or punished.

• Motivation: Motivation depends on direct/indirect reinforcements & punishments. i.e. if rewarded the motivation is to repeat the behaviour, if punished the motivation is not to repeat it.

Social Learning Theory.

0

2

4

6

8

10

12

model rewarded

model punished

boys girlsBandura’s Bobo

Doll experiment

Modelling of

aggressive behaviour

Evaluation of SLT & Bobo doll experiment.

Artificial- Hitting a doll is not the same as hitting a person. (So lacks external/ecological validity)

Demand Characteristics - Why might this be a valid criticism?

The theory neglects the importance of innate factors. (e.g. Gender differences, evolutionary driven) Also biological; physiological, hormonal, genetic, inherited personality differences etc!

Can you think of some positive criticisms that support this theory?

So if children do learn aggression by simply watching it on TV then should cartoons like

those seen on the following compilation be banned?

http://www.youtube.com/watch?v=iqVd2qyEJhY

Activity : Evaluating the Social Learning Theory of Aggression.

• Complete the Activity sheet Aggression- Social psychological approaches to explaining aggression. You will need to use text books and/or the internet to do this.

Imagine you were invisible for 24 hours & were completely assured that you would not

be detected or held responsible for your actions,

• What would you do? • Think carefully for a minute without discussing it with

anyone else then....• Write down one thing you would do on the piece of

paper I give you.• Do not let anyone else see it.• Fold the paper up into a small square and hand it in to

me.• You will not need to disclose which was your choice.

ST3

Results

• A similar study to this was completed by a psychologist called Dodd (1985)

• Dodd found that the number of anti-social responses was 36%.

• This was the same percentage given by inmates at a maximum security prison where Dodd once taught!

• Are you more moral than them?

• Deindividuation- Loss of self awareness and sense of personal responsibility.

• Normal constraints on behaviour are weakened when a person loses their sense of individuality– Crowds, uniforms, drugs & alcohol– Less likely to be identified & held responsible for aggressive

behaviour– Anonymity deindividuation aggression – As a result of feeling anonymous you engage in behaviour

that you would normally refrain from. This has been used as a explanation for crowd violence AND as an explanation of the actions of participants in both Zimbardo & Milgram’s studies.

Other social psychological explanations:

DEINDIVIDUATION:

• Recap: the Stanford Prison Experiment.

• What were the explanations you learned were the likely causes of the aggressive behaviour of the guards?

• How does deindividuation fit in?

http://www.youtube.com/watch?v=RKW_MzREPp4

Social Causes of Aggression 2. Deindividuation

Deindividuation

Explain why these episodes were likely to result in aggressive behaviour (i.e. identify the features that lead to deindividuation).

London riots- 2011?

Deindividuation

Neo Nazi rally, Holland, 1980s

Deindividuation

Riot police in Canada 2001

Deindividuation

They act as one, think as one and therefore behave as one…… and do not feel responsible

for their own actions.

Deindividuation

And the younger they are…… the easier it is to abdicate the responsibility for your actions…..

• Trick or treat study (Diener et

• al. 1976)

• – Children trick or treated alone or

• in group

• – 1/2 Trick or treating children

• asked name; other 1/2 not

• – All children given the opportunity

• to steal extra candy

Deindividuation – Research Findings

Evaluation of Trick or Treat Study High ecological validity Although a large sample was used they were all children so would the same findings be applicable to adults? The study examined anti-social behaviour (stealing sweets rather than aggression.

Deindividuation – Research Findings

• Mullen (1985)– Violence of mob lynching a

function of crowd size

• Zimbardo (1970)– Hooded Ps were more

aggressive

• Zimbardo (1973; Stanford Experiment)– Guards’ aggression

increased by uniforms, sunglasses, night-time

http://www.youtube.com/watch?v=QcWrQnW8Gfw&feature=fvsr

Deindividuation

Zimbardo suggested that……

• Individuated behaviour is rational and consistent with personal norms

• Deindividuated behaviour is more unrestrained, acting on primitive impulses and often leads to anti social acts i.e. football hooliganism, lynch mobs.

Remember Stanley Milgram: Obedience to Authority?

Did deindividuation have a role in the actions of

Milgram’s participants?

Milgram’s Obedience

Studies:

• Predictions• Experts thought only 1-3% would keep going

• Psychopaths

• Also thought that they themselves would never obey

• Results• 65% obeyed to the end (450 v.)• Males and females obeyed• More or less the same across cultures• 100% obey up to 300 v.

Situational Factors in Aggression

Deindividuated = a reduced capacity to think of oneself as an individual, particularly in terms of societal or moral standards, resulting in a loss of self-awareness.

Zimbardo replicated Milgrams work in 1970 with dindividuated (masked/hooded) ‘teachers’ how do you think his results differed from Milgrams?

Deindividuation...Evaluation.On some occasions deindividuation actually

leads to more pro-social behaviours e.g. nurses, policeman etc.

An individual can act independently deindividuation is not always inevitable.

Individuals differ morally and in terms of strength of character and intelligence so may be more or less likely to be affected by deindividuation.

Frustration-aggression hypothesis http://www.youtube.com/watch?v=fPxsVzR7Gqs

• Dollard (1939) Excitation-transfer

theory

Zillman (1971)

Cue arousal

• Berkowitz and LePage (1967)- frustration may lead to anger, but not always to aggression: there needs to be a cue or stimulus to spark the aggressive behaviour.

http://www.youtube.com/watch?v=d_FysQg1Qp4

Relative deprivation

• Hovland and Sears (1940)

• Stouffer (1950)

• Runcimann (1966)

• Wright and Klee (1999)

• Doward and Hinsliff (2004)

http://www.youtube.com/watch?v=a9VW7LRmOpY

Relative Deprivation and Collective Behaviour

Deprivation Theory– Collective behaviour arises among people who feel depriveddeprived

– Relative deprivation – a perceived disadvantage arising from some specific comparison e.g. them & us.

– Critical evaluation• Why does collective behaviour arise among

some groups and not others?

Collective ViolenceRelative deprivation

Frustration

Aversive environmental conditions(e.g., ‘heatwave’) amplifies frustration

Individual acts of aggression exacerbated byaggressive stimuli (e.g., armed police)

Individual acts of aggression

Aggression becomes more widespread andAssumes role of dominant response

Source: Berkowitz (1972)

Aggression spreads rapidly through socialfacilitation process

Collective violence

Summary Activity: Social Explanations of Aggression

• Social Learning Theory and Deindividuation are some Social Psychological Explanations of Aggression.

• Think of real-life examples of aggression to illustrate each explanation, e.g. football riots for deindividuation, and present as a mind map/poster.

• Entitle your poster for example: “ Football Violence: SOCIAL EXPLANATIONS OF AGGRESSION”.

• Explain the behaviours using the theories & include relevant research.

• Make sure you EVALUATE the theories and studies you mention. i.e. also explain how obedience and conformity may be factors as well as biological processes (high testosterone levels)

Activity: Write a psychological report, story, song, rap or cartoon.

Write about two men who enter prison. One of them from a violent slum/gang background and the other from a ‘good’ home, a well

educated accountant.

In your story explain how they both eventually resort to aggression.

INCLUDE An explanation of their behaviour related to:

•The models (Importation, Deprivation or Integration)•Consider other explanations relating to social, personal and environmental factors.•USE YOUR HANDOUT “Explanations of institutional aggression” FOR THIS. •Mention models such as the ‘popcorn model’ etc.

I WILL CHOSE SOME FOR READING OUT TO CLASS AFTERWARDS: GOOD LUCK – BE CREATIVE!

Biological/Genetic Explanations for Aggression

ST5

• Aggression is due to our genes, body hormones, brain anatomy and neuronal mechanisms.

• Are men then born to be aggressive or even born to be killers?

• Video clip – Natural born killers http://www.youtube.com/watch?v=4_67t6I_beg

Key areas

• Genetic factors

• Biochemical influences (hormones, neurotransmitters)

• Brain structure influences

What links the 3? Aggression is simply the by-product of complex internal physiological processes.

1. The BRAIN: Neural mechanisms in aggression. • Neural influences on

aggression- stimulating the amygdala in cats causes a fearful or anger response to occur (piloerection).

• A woman receiving painless stimulation to her amygdala became enraged and smashed her guitar against the wall.

Which other brain structures are involved in aggressive behaviour?

• Rat lesion studies suggest that different types of aggression may be controlled by different subsets of brain structures.

– Limbic sites: (amygdala, septum and hypothalamus)

Are violent people’s brains different from normal

people?• Yes!!!• Raine et al., (2000) found that the prefrontal

cortex (which inhibits aggressive behaviour), was 14% less active than normal in non-abused murderers &15% smaller in anti-social males.

• This is correlational so this does not mean brain anomaly caused aggressive behaviour (could be the other way around), but could be a factor

• Electrical stimulation of the amgydala however, increases all types of aggression

• Charles Whitman (Austin, Texas; University tower mass murderer) left a note begging for his brain to be studied. His autopsy revealed he had a tumor pressing on into his amygdala

.

Evidence:Phineas Gage

• Railroad Accident – Sept. 1848• Levelling land with dynamite• 3 foot inch thick tamping rod was

projected in to his brain• Entered via cheek, left Eye and into

the frontal lobes• Driven by other workers in a ox cart

to doctor’s office• The rod damaged the pre-frontal

cortex. This region is implicated in personality changes and aggression/violence.

What happened?

• Lost conscious and had convulsion immediately, but awoke quickly and was talking and walking soon afterwards

• Never showed any impairment of movement or speech• Memory was intact, and was capable of learning new things• However, within months his personality had changed dramatically

– He became extravagant and anti-social, a foul mouth liar with bad manners, frequently got into fights and assaults.

– could no longer hold a job or plan his future • According to friends “Gage was no longer Gage”, he died 13 years later

– A penniless, epileptic

2. Alcohol & Aggression• Individuals prone to aggression are more

likely to drink & become aggressive while drunk. – (Alcohol effects the brain).

4 in 10 violent crimes committed by people who’ve been drinking.

• Surveys of rapists--over half report they were drinking before committing the rape.

• Alcohol – reduces self-awareness & disinhibits (deindividuates). It also ‘switches off the frontal areas leaving the aggressive ‘limbic’ areas without cognitive control!

3. Hormones involved in Aggressive Behaviour (Testosterone): EVIDENCE• Research shows that lowering

testosterone levels reduces aggressiveness, while raising it, increases aggression

• Prisoners who had committed unprovoked violent crimes had higher levels of testosterone than those who had committed nonviolent crimes.

• Teens with higher levels of testosterone were more prone to delinquency, hard drug use, & provocations.

Sex and Testosterone

• Social psychologist Jim Dabbs & colleagues found high testosterone levels in:– Aggressive boys– Violent criminals– Men and women with criminal

records– Military veterans who went AWOL or

got into trouble after their service

Sex and Testosterone

• Dutch psychologist Stephanie VanGoozen & colleagues (1995, 1997) studied people undergoing sex change operations:– Women changing to men got

testosterone injections – became more aggressive and sexual

– Men changing to women got testosterone suppressants – became less aggressive and sexual

(Serotonin: the happy homone?)

• Lower levels of serotonin are found in children & adults prone to violence.

• Lowering serotonin levels in the lab increases their response to aversive events and willingness to deliver supposed electric shocks.

• Evidence: Mann (1990) when levels of serotonin were artificially reduced by a drug participants responses to a hostility and aggression questionnaire were increased. (Not in females though!)

• Evidence: Cases (1995) when participants are given serotonin it causes a calming effect and a lowering of aggressive responses.

4. Genes: Is aggression genetic?

• Possibly.

• We can breed animals for aggressiveness (pit bulls, roosters).

• Our temperament in infancy predicts whether we will be aggressive in adulthood (Larsen & Deiner, 1987).

• Twin studies support this- but only to a degree.

Genetics: Aggression as a biological predisposition

2 constants across cultures:

1. Men are most likely to commit violent acts.

• Sex difference is a universal. • Average man is more aggressive then women

even in infancy prior to sex role socialization by adults.

• In USA 85% of arrests for violent crimes are men.

2. Young persons are more likely to be violent than older persons

EVIDENCE:Adoption studies

• 1,000 boys adopted in Denmark between 1927-1947.

• Groups  – 1. Children of violent criminal biological

parents adopted to non-criminal parents– 2. non-criminal biological parents adopted by

criminal parents• Group 1: were the most likely to be violent

criminals, plus the more extensive criminal history of biological parents the higher risk the child is a criminal.

Activity: Aggression & Free Will MURDERERS ON TRIAL:

• We are going to try a Murderer• You will be assigned to either the defence or the

prosecution of either a young man or woman accused of murder. When not taking part you will be the jury!

• You must prepare your case carefully for the trial. Make sure you research your argument.

• The defence’s argument should focus on the murderer having no ‘free will’ i.e. their aggression was due to biological factors beyond their control. (Supporting evidence will be needed.)

• The prosecution should give the opposite view also giving relevant supporting evidence.

• Use handouts, internet and textbooks available.

The effects of aggression on the brain

• http://www.psychexchange.co.uk/tag/aggression/

Evolutionary Explanations of Aggression

• How could aggression have evolved to help us survive?

• How does it benefit the survival of ourselves and our offspring?

• Give examples of different types of aggressive behaviour that may be explained by adaptation, selfish gene theory or survival of the fittest.

ST6

What is the aim of evolution?

Reproduction Females

Resources

Territory

Survival

Evolutionary Explanations of Aggression:

• Evolutionary - aggression may be an adaptive response. Aggression enables us to obtain resources, defend against attack, eliminate competition for mates, & to enforce sexual fidelity from mates.

• Also called ‘Instinct’ theories: – suggest aggression is a part of human nature– Aggression is an instinct, perhaps an inevitable

part of human behaviour– We are ‘programmed’ for violence by our

biological nature (deterministic – no free will!)

Aggression as an Adaptive Response – Evolutionary Explanation

Leading Proponent: Konrad Lorenz (Ethologist). The idea that humans are born violent and aggressive is normally attributed to the Konrad Lorenz, who, from studies of animal behaviour, argued that aggression is part of human genetic equipment

Instinct Theory:

Through evolution, humans have inherited a fighting instinct similar to that found in many species of animals.

He says we have a biological need for aggression. It gets stronger as time passes since the last aggressive act (like hunger increases hours after a meal).

This causes our energy level (drive level) to increase. This energy must somehow be released (“catharsis”).

“Our motivation for aggression increases when our ongoing behaviour is interrupted or we are prevented from reaching a goal.” (frustration – aggression hypothesis).

Instinct Theory

This Theory predicts:

• 1. Aggression is inevitable - the accumulating energy must find an outlet

• 2. Humans & animals will actively 'look for fights'.

• 3. After an attack an animal / human will become less aggressive.

• 4. Animals reared in isolation will still show aggressive behaviour.

Instinct Theory says that: Humans learn their own individual ways of expressing aggressive motivation. But … aggression in self defence or defending a child or family member may be instictive.Non-human animals behave in ways that are genetically programmed and characteristic of all members of the species.This ‘Fixed Action Pattern’: unlearned complex behaviour is found in all members of a species (or subgroup), it is usually triggered by a very simple stimulus in the environment (“releaser”).

Ethological Explanations• Ethology explains aggression therefore as:

– Aggression being innate: Man is born to be aggressive with traits that ensure this.

– The aim of aggressiveness- Survival by:• Winning or controlling territory• Increasing solidarity between males and females• Becoming and maintaining a dominant role• Natural selection trough the survival of the fittest

Evolutionary analysis of aggression

Aggression then is the solution to a range of adaptive problems – i.e., solving these problems would have enhanced the survival and reproductive benefits of the actor; hence, this design would have spread through the population

What are these adaptive problems? (Buss, 1999, 2005)

• How to get valuable resources that others have;• How to defend oneself against exploitation or

physical attack;• How to deter others from aggression against you;• How to climb up in the dominance hierarchy of a

group;• How to inflict costs on intra-sexual rivals;• How to deter long-term mates from (sexual)

infidelity;• How to get access to mates;

Context specifity of aggression

• Aggression is likely to be highly context specific: – it is only elicited in situations that resemble

adaptive problems faced by ancestors– different forms of aggression should be

elicited in different contexts (e.g., gossip to lower someone’s status in hierarchy; stealing to get access to their resources)

So, which adaptive problems make people likely to show each of these behaviours?

One man killing another man in a bar fight A woman gossiping about the promiscuity

of her female colleague Stealing from a shop keeper Killing one’s sister who lost her virginity

before marriage Shooting at an enemy soldier Carrying a knife to school

Problems with instinct theory:

Instinct theory fails to account for variations in aggressiveness across individuals & cultures.

E.g., How does instinct theory account for peaceful Iroquois before white invaders & aggressive Iroquois afterwards?

The criticism against Lorenz does not question his analysis regarding animals but rather question the meaningfulness in comparing animals and humans

Other critics argue that human aggressive tendencies are socially learned rather than natural

However, the biological literature is generally consistent with evolutionary hypotheses

Social psychological evidence for each of these evolved functions of aggression

1. Getting valuable resources that others have

• Childhood aggression about toys and territory (Campbell, 1993; Sherif, 1961)

• Boys more than girls (Campbell, 1993)• Research on realistic intergroup conflict theory (Campbell, 1961)• Stealing, robbery, fraud, drug killings in every society

Men tend to engage in this more than women, any idea why?

2. Defending oneself against exploitation or physical attack

• Retaliation in the prisoner’s dilemma, Playing a tit-for-tat strategy (nice but firm)

(Axelrod, 1984)• Women and men are equally likely to retaliate (Ledyard,

1995)• Ostracizing or excluding cheaters from groups (Kurzban

& Leary, 2001; Williams’ work on ostracism)

3. Deterring others (rivals) from aggression against you

• Making a first cooperative choice in the Prisoner’s Dilemma Game (being nice)

• Getting a reputation as someone who carries out a threat (Frank, 1988)– Carrying a knife to the pub – having an “aggressive” tattoo– Others?

• Men probably more than women??

4. Climbing up in the hierarchy of a group

• Within street gangs and traditional societies, men get status as “warriors” – reputations important (Campbell, 1993; Chagnon, 1997) – how many outgroup members have you injured/killed? Male soldier hypothesis (Van Vugt et al.)

• Bullying by dominant children in group – more common among boys (Ahmad & Smith, 1994), but do girls bully differently?

• But, why in some societies do people get status via altruism and in others via aggression?

5. Inflicting costs on intrasexual rivals

• Male-to-male violence prevalent among young males in virtually all societies (Daly & Wilson, 1988) – homicide statistics

• Interest in violent videogames (Bushman’s research)

• Interest in “aggressive” movies • Boys more than girls use direct aggression• Girls more than boys use indirect aggression

(behind the back); Archer & Coyne, 2005;

6. Deterring long-term mates from infidelity

• Domestic violence• Male sexual jealousy and female emotional jealousy

(Buss, 1999; Buunk et al., 1996); how strong is the evidence?

• In US, one third of homicide against females is by their husband/boyfriend (Daley & Wilson, 1999)

• Wife-to-husband violence is also common• Possibly out of self-defence?? (Archer, 2000)

7. Aggression to acquire / retain a mate

• Theory of rape (Thornhill & Gangestad); rape as adaptive mating strategy (or simply by product of aggression?)

• Date rape among college students• Ensuring sexual fidelity- does this explain battered

wives?• How do women use aggression to acquire a mate?

Sex differences: Evolution and mating strategies

Issue Females Males

Reproductive constraints A limited number of children No constraints on reproduction

Optimal strategy Best quality mate Largest number of mates

Desired mate quality Resources, fidelity Childbearing capacity, promiscuity

Indications of quality Earning capacity, status, Physical attractiveness, health, possessions, generosity, youth

ambition

Most likely basis for jealousy Emotional attachment to other Sexual attachment to otherby partner (certainty of resources) (certainty of paternity)

Contagion Theory• People are influenced by the way the group

acts (the one bad egg theory) – do not need to think similarly, more like social influence.

Because individuals are capable of violence, we conclude that it must be in our nature. However uncontrolled violence is not the best behavioural strategy in a community because the costs are too high.

This might lead us to consider the strengths and weaknesses of an evolutionary theory.

Emotions including revenge, spite, happiness and anger, must have evolved because most of the time they motivate fitness-enhancing behaviour.

Aggressiveness has evolved in some species in which it increases an individual’s survival or reproduction and this depends on the specific environmental, social, reproductive and historical circumstances of a species.

Humans rank amongst the most violent of all species.

Some male insects are more likely to closely guard their mates when there are fewer females in the population, hence fewer mating opportunities.

Evolution didn’t just shape us to be violent or peaceful, it shaped us to respond flexibly, adaptively to different circumstances and to risk aggression when it makes adaptive sense.

Maynard Smith and Price ( 1973) defined an Evolutionary Stable Strategy (ESS) as a type of behaviour that dominates a community to such an extent that it will not change.It is thought that whereas ritualised displays of aggression are an example of ESS, actual acts of aggression will often not be tolerated.In small communities, people who show uncontrolled aggression are feared and may become a target of collective action by the community. (Lee 1969)