2. 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
3. AO1: Outline definitions of aggression & types of
aggression
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
4. 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!
5. 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
6. 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, mafia
http
://www.youtube.com/watch?v=__kf7TljgG
7. 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.
8. Types of Aggression
Physical Verbal
Hitting
Active Name
Calling
Gossiping
Angry
Passive looks
9. 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’
10. A person mentally rehearses a plannedabused his child a window box
A father attacks someone who Someone knocks over
has murder
Soldier shooting an enemy
A lion brings down a gazelle Which falls and injures a passer-by
A driver gets drunk and knocks over a pedestrian
Couple are tussling with one another. A person at a party
The ‘victim’ laughs! gossips in a
Angry child kicksdisparaging way
and hits a chair.
about someone.
Prison wardens executing a prisoner
11. 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?
12. LO: Outline & evaluate explanations of aggression
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.
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
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?
13. 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 condition
The 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.
14. Bandura Ross Ross (cont…)
• Consequence 2: model-punished condition
The 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 condition
Here, 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.
15. Theories of Aggression
1. Social Learning Theory (SLT)
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.
16. 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.
17. 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.
18. Social Learning Theory.
Bandura’s Bobo boys girls
Doll experiment 12
10
Modelling of
8
aggressive behaviour
6
4
2
0
model model
rewarded punished
19. 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?
20. 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
21. 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.
22. ST3
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.
23. 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?
24. Other social psychological
explanations:
DEINDIVIDUATION:
• 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.
25. Social Causes of Aggression
2. 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
26. Deindividuation
London riots- 2011?
Explain why these episodes were likely to result in aggressive
behaviour (i.e. identify the features that lead to deindividuation).
31. Deindividuation – Research Findings
• 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
32. 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.
33. Deindividuation – Research Findings
• Mullen (1985)
– Violence of mob lynching a
function of crowd size
• Zimbardo (1970)
– Hooded Ps were more http://www.youtube.com/watch?v=Qc
aggressive
• Zimbardo (1973; Stanford
Experiment)
– Guards’ aggression
increased by uniforms,
sunglasses, night-time
34. 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.
35. Remember Stanley Milgram:
Obedience to Authority?
Did deindividuation have a
role in the actions of
Milgram’s participants?
36. 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.
37. 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?
38. 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.
40. 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
41. Relative deprivation
• Hovland and Sears (1940)
• Stouffer (1950)
• Runcimann (1966)
• Wright and Klee (1999)
• Doward and Hinsliff (2004)
http://www.youtube.com/watch?v=a9VW7LRmO
43. Deprivation Theory
– Collective behaviour arises among
people who feel deprived
– 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?
44. Collective Violence
Relative deprivation
Frustration
Aversive environmental conditions
(e.g., ‘heatwave’) amplifies frustration
Individual acts of aggression
Individual acts of aggression exacerbated by
aggressive stimuli (e.g., armed police)
Aggression becomes more widespread and
Assumes role of dominant response
Aggression spreads rapidly through social
facilitation process
Source:
Collective violence Berkowitz
(1972)
45. 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
46. 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!
47. ST5
Biological/Genetic Explanations
for Aggression
• 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
48. 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.
49. 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.
50. 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)
51. 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
.
52.
53. 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.
54. 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
55. 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!
56. 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.
57. 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
58. 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
59. (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.
60. 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.
61. 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
62. 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.
63. 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.
64. The effects of aggression on the brain
• http://www.psychexchange.co.uk/tag/aggressio
65. ST6
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.
66. What is the aim of evolution?
Reproduction Females
Survival
Resources
Territory
67. 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!)
68. Aggression as an Adaptive Response
– Evolutionary Explanation
Instinct Theory:
Through evolution, humans have inherited a
fighting instinct similar to that found in many
species of animals.
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
69. Instinct Theory
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).
70. 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.
71. 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”).
72. 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
73. 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
74. 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;
75. 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)
76. 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
77. 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
78. 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?
79. 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)
80. 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??
81. 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?
82. 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 &
83. 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)
84. 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?
85. 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 other
by partner (certainty of resources) (certainty of paternity)
86. 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.
87. 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.
88. 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.
89. 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.
90. 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)
