Social Psychology II: Relations
Contents
Chapter 1: Evolutionary psychology.......................................................................................2
Chapter 2: Social Interaction and Dilemmas...........................................................................8
Chapter 3: Aggression.......................................................................................................... 18
Chapter 4: Prosocial Behavior..............................................................................................30
Chapter 5: Social influence...................................................................................................42
Chapter 6: Attraction and close relationships........................................................................57
Chapter 7: Emotions............................................................................................................. 69
,Chapter 1: Evolutionary psychology
Altruism and natural selection: an evolutionary perspective on
human nature
Natural selection and behavior
Darwin (1859): “The origin of Species”
- Theory of natural selection: Selection in nature occurs because some organisms
survive better and reproduce better in a certain environment
- Survival of the fittest: You will survive when you have good adaptation to the
environment
- Better fitness: How well you transfer your genes to the next generation
- Primary interest of fitness: evolution of physical features
- Species have a lot of offspring, with a lot of variation: Each species shows
variation:
- We had giraffes with long necks and giraffes with shorter necks
- The ones with the long necks could reach the good leaves to
eat, which is mandatory for survival
- The ones with the long necks will survive, the ones with the
short necks won’t.
- Evolution of physical features: classic evolutionary psychology
- New interest, modern Darwinism: evolution of behavior (altruistic behavior)
- Evolutionary perspective on human nature
Modern Darwinism
Universal characteristics: These successful characteristics provide such an evolutionary
advantage, that they spread throughout the population and become typical for all mankind
- Bipedalism: Humans walk straight, on their feet, and you can hold something in your
hand while moving at the same time, universal!!
- Universal psychological features/characteristics: Such as emotions, language,
theory of mind, moral reasoning etc
Altruistic behavior
= Helping others although it may be detrimental to your own fitness.
- Natural selection = seemingly selfish process
- How to explain this?
- Humans have a universal need to belong
- Baumeister & Tyce (1990): “social anxiety” as an adaptation to prevent
exclusion from a group which is crucial for survival.
- A warning system: It alerts individuals that they might be acting in
ways that could lead to rejection.
- Social anxiety: the distress about being negatively evaluated or to be
excluded (a good thing)
,Inclusive fitness and kinship (Hamilton, 1964)
= Your personal reproductive success + the effects you have on the reproduction of your
genetic relatives, weighted by the degree of genetic relatedness
- Identical twins: genetic relatedness: 100%
- Parents/child: 50%
- Brother/sister: 50%
- Aunt/uncle: 25%
- Cousins: 12,5%
→ Saving your relatives is also saving your own genes.
= Better fitness (of next generation) by helping (genetic) relatives
→ This implies:
- One takes risks for genetic relatives
- The higher the genetic relatedness, the higher the risk one takes
- Daly & Wilson, 1988
- There would be less care by step-parents than biological parents
- More child abuse by step-fathers (100 x more than biological fathers)
- The relatedness between children and step-parents is almost non existent, so
there is no big need for inclusive fitness and kinship
- Burnstein et al, 1994
- More help towards genetic relatives in trouble
- Study: To test whether people are more likely to help others based on
genetic relatedness, especially when the help involves life-or-death
situations.
- Participants were asked to imagine hypothetical scenarios
- We are less likely to help people less related to us
- Who we help in different situations is predictable from an evolutionary
perspective
- Strong evidence for the inclusive fitness theory
- Ex. House on fire:
- In everyday situations, the higher the genetic relatedness, the higher
the tendency to help
- Also in life or death situations
- Ex. Tendency to help, related to age of the person in need:
- People help the ones most in need: U shape curve: the really old and
really young ones: Everyday situation
- People help the younger ones more often: Life or death situations
- Important difference: Older people can't reproduce anymore and it is
better to save children who are still able to reproduce
- Ex. Tendency to help under famine conditions (hongersnood)
- Peek around the age of 10
- People will help children of 10 more often than babies
- Makes sense: The 10 year olds: reproductive age is already nearby
- For babies: It is extremely hard to survive for them in famine
conditions, and it takes too long for them to reach reproductive age
- 10 year olds are helpless. After some time they can eventually help
themselves
, Tendency to help kin under life Tendency to help as a function of Tendency to help under famine conditions
or-death versus everyday condi- the recipient’s age under l.o.d. vs
tions everyday conditions
More likely to help younger kins than More likely to help young children, less likely to
More likely to help kins older kins in l.o.d. situations help other people
Reciprocal altruism
Reciprocal altruism is a concept from evolutionary biology and psychology that describes a
behavior in which one organism helps another, with the expectation that the favor will be
returned in the future.
- Why do we help unrelated individuals?
- “I help you when you help me”
- Only possible if:
- The person being helped can be recognized later
- Deceivers can be punished: cheaters are excluded
- Only in intelligent species (primates, humans)
- Only with acquaintances and small groups/tribes (guarantees reciprocity)
- In the end, helping increases fitness!
Sexual selection and sex differences in behavior: an
evolutionary perspective on sex differences
Sexual selection and parental investment
Sexual selection
Forms of sexual selection/competition:
- Intrasexual competition: Competition between members of the same sex (usually
males) for access to mates. (within the sex)
- Intersexual competition: between males and females, choosing a mate based on
their preferences (female choice) (between the sexes)
- Ex. When the brown peacocks are not preferred, they will not survive long term
Parental investment theory
The sex that invests more in offspring (typically females) will be more selective in choosing
mates, while the sex that invests less (typically males) will compete for access to the high-
investing sex.
- A woman is physically restricted in having kids during time (one a year logical)
(record: 69 children)
- Men can have children any day they want (record: 1000+)
This will result in several sex differences.
Contents
Chapter 1: Evolutionary psychology.......................................................................................2
Chapter 2: Social Interaction and Dilemmas...........................................................................8
Chapter 3: Aggression.......................................................................................................... 18
Chapter 4: Prosocial Behavior..............................................................................................30
Chapter 5: Social influence...................................................................................................42
Chapter 6: Attraction and close relationships........................................................................57
Chapter 7: Emotions............................................................................................................. 69
,Chapter 1: Evolutionary psychology
Altruism and natural selection: an evolutionary perspective on
human nature
Natural selection and behavior
Darwin (1859): “The origin of Species”
- Theory of natural selection: Selection in nature occurs because some organisms
survive better and reproduce better in a certain environment
- Survival of the fittest: You will survive when you have good adaptation to the
environment
- Better fitness: How well you transfer your genes to the next generation
- Primary interest of fitness: evolution of physical features
- Species have a lot of offspring, with a lot of variation: Each species shows
variation:
- We had giraffes with long necks and giraffes with shorter necks
- The ones with the long necks could reach the good leaves to
eat, which is mandatory for survival
- The ones with the long necks will survive, the ones with the
short necks won’t.
- Evolution of physical features: classic evolutionary psychology
- New interest, modern Darwinism: evolution of behavior (altruistic behavior)
- Evolutionary perspective on human nature
Modern Darwinism
Universal characteristics: These successful characteristics provide such an evolutionary
advantage, that they spread throughout the population and become typical for all mankind
- Bipedalism: Humans walk straight, on their feet, and you can hold something in your
hand while moving at the same time, universal!!
- Universal psychological features/characteristics: Such as emotions, language,
theory of mind, moral reasoning etc
Altruistic behavior
= Helping others although it may be detrimental to your own fitness.
- Natural selection = seemingly selfish process
- How to explain this?
- Humans have a universal need to belong
- Baumeister & Tyce (1990): “social anxiety” as an adaptation to prevent
exclusion from a group which is crucial for survival.
- A warning system: It alerts individuals that they might be acting in
ways that could lead to rejection.
- Social anxiety: the distress about being negatively evaluated or to be
excluded (a good thing)
,Inclusive fitness and kinship (Hamilton, 1964)
= Your personal reproductive success + the effects you have on the reproduction of your
genetic relatives, weighted by the degree of genetic relatedness
- Identical twins: genetic relatedness: 100%
- Parents/child: 50%
- Brother/sister: 50%
- Aunt/uncle: 25%
- Cousins: 12,5%
→ Saving your relatives is also saving your own genes.
= Better fitness (of next generation) by helping (genetic) relatives
→ This implies:
- One takes risks for genetic relatives
- The higher the genetic relatedness, the higher the risk one takes
- Daly & Wilson, 1988
- There would be less care by step-parents than biological parents
- More child abuse by step-fathers (100 x more than biological fathers)
- The relatedness between children and step-parents is almost non existent, so
there is no big need for inclusive fitness and kinship
- Burnstein et al, 1994
- More help towards genetic relatives in trouble
- Study: To test whether people are more likely to help others based on
genetic relatedness, especially when the help involves life-or-death
situations.
- Participants were asked to imagine hypothetical scenarios
- We are less likely to help people less related to us
- Who we help in different situations is predictable from an evolutionary
perspective
- Strong evidence for the inclusive fitness theory
- Ex. House on fire:
- In everyday situations, the higher the genetic relatedness, the higher
the tendency to help
- Also in life or death situations
- Ex. Tendency to help, related to age of the person in need:
- People help the ones most in need: U shape curve: the really old and
really young ones: Everyday situation
- People help the younger ones more often: Life or death situations
- Important difference: Older people can't reproduce anymore and it is
better to save children who are still able to reproduce
- Ex. Tendency to help under famine conditions (hongersnood)
- Peek around the age of 10
- People will help children of 10 more often than babies
- Makes sense: The 10 year olds: reproductive age is already nearby
- For babies: It is extremely hard to survive for them in famine
conditions, and it takes too long for them to reach reproductive age
- 10 year olds are helpless. After some time they can eventually help
themselves
, Tendency to help kin under life Tendency to help as a function of Tendency to help under famine conditions
or-death versus everyday condi- the recipient’s age under l.o.d. vs
tions everyday conditions
More likely to help younger kins than More likely to help young children, less likely to
More likely to help kins older kins in l.o.d. situations help other people
Reciprocal altruism
Reciprocal altruism is a concept from evolutionary biology and psychology that describes a
behavior in which one organism helps another, with the expectation that the favor will be
returned in the future.
- Why do we help unrelated individuals?
- “I help you when you help me”
- Only possible if:
- The person being helped can be recognized later
- Deceivers can be punished: cheaters are excluded
- Only in intelligent species (primates, humans)
- Only with acquaintances and small groups/tribes (guarantees reciprocity)
- In the end, helping increases fitness!
Sexual selection and sex differences in behavior: an
evolutionary perspective on sex differences
Sexual selection and parental investment
Sexual selection
Forms of sexual selection/competition:
- Intrasexual competition: Competition between members of the same sex (usually
males) for access to mates. (within the sex)
- Intersexual competition: between males and females, choosing a mate based on
their preferences (female choice) (between the sexes)
- Ex. When the brown peacocks are not preferred, they will not survive long term
Parental investment theory
The sex that invests more in offspring (typically females) will be more selective in choosing
mates, while the sex that invests less (typically males) will compete for access to the high-
investing sex.
- A woman is physically restricted in having kids during time (one a year logical)
(record: 69 children)
- Men can have children any day they want (record: 1000+)
This will result in several sex differences.
