Aggression: The Role of Nature

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Aggression The Role of Nature

• Soundtrack
• Bohemian Rhapsody (Queen)
• Mack the Knife (Bobby Darin)
• To what extent is aggression caused by
• internal (innate, genetic, or biological)
• Factors
• For students who participated in the
• survey earlier in the semester 2nd part to be
• handed out on Tues.
• Study Guide for Exam 4 is now available

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Is it aggression?

• Exercise

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What is aggression?

• Aggression Intentional behavior aimed at
  causing either physical or psychological pain.
• Key feature Intention
• Not the same as assertive or ambitious
• Examples
• Beer bottle at party
• Drunk driver

4
Why might people behave aggressively?

• Is aggression inborn?
• Instinct theorists
• Freud Aggression innate, destructive
• Freud Death instinct (Thanatos) innate impulse
  for self-destruction. Opposite of life instinct
  (Eros).
• Lorenz Aggression innate, but adaptive.
• Ethologist. Emphasized that aggressive instinct
  facilitates the individuals survival,
  reproduction.

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Instinct theories

• Instinct theories are NOT widely accepted.
• Problems with assuming that aggression is innate

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Problems w/Instinct Theories

• Humans vary greatly in aggressiveness.
• Cross-cultural differences (groups in South Seas
  vs. Yanomamo in South American Iroquois and
  social change)

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Problems w/Instinct Theories

• Regional differences in aggressive behavior
• Culture of honor Homicide rates for males are
  significantly higher than those for white
  northern males, especially in rural areas. But
  this is true only for "argument-related"
  homicides.

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Culture of honor experiments (Dov Cohen, Richard
Nisbett colleagues)

• IV A confederate accidentally bumped into the
  participant, and called the P an insulting name
  (or no incident in the control condition).
• DVs Ps guess about evaluators ratings of his
  masculinity his physiological response to
  stress and his behavior
• Results Southerners in insult condition were
  than northerners to think they would be seen as
  less masculine, experienced increased cortisol
  and testosterone, and were slower to move out of
  the confederates way in a very narrow
  passageway.

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Problems w/Instinct Theories

• If aggression is a human instinct, then it is
  hard to account for this variability both within
  and between cultures.

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Problems w/Instinct Theories

• Circular reasoning
• Why do sheep herd? Because they have a herding
  instinct.
• Doesnt explain the phenomenon, just names it.

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Biological influences on aggression

• Neural influences
• AMYGDALA -- associated with aggressive behavior
  in humans and in lower animals.
• When electrically stimulated, docile animals
  become violent when neural activity in the
  amygdala is blocked violent animals become
  docile.

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Neural influences Interaction w/environment

• Social factors can influence the impact of these
  neural mechanisms.
• If a male monkey is in the presence of other,
  less dominant monkeys, he will attack the other
  monkeys when the amydala is stimulated.
• But if the amygdala is stimulated while the
  monkey is in the presence of more dominant
  monkeys, he will not attack but will run away
  instead.

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Chemical/hormonal influences

• Testosterone
• Injection of testosterone will increase
  aggression in animals (cause and effect
  relationship in non-human animals)

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Testosterone in humans

• Dabbs and colleagues
• Naturally occurring testosterone levels are
  higher among prisoners convicted of violent
  crimes than those convicted of nonviolent crimes.
  
• Once incarcerated, prisoners with higher
  testosterone levels violated more prison rules
• Compared fraternities within a given college
  those known to be more rambunctious, less
  socially responsible, and more crude had the
  highest average testosterone levels.
• Correlational Questions about direction of
  causality and third variables

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• Behaving aggressively also can increase
  testosterone
• 3rd variables Violent prisoners may differ in
  many ways from less nonviolent prisoners (e.g.,
  in stress, family history, etc.)
• However, people opting for sex reassignment show
  more aggression as testosterone is increased.
  (Still correlational and not a random sample
  expectations may influence)

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Genetic influences

• Are people who are more aggressive genetically
  different from those who are less aggressive?
• Can breed animals to be more or less aggressive

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Genetic influences

• Twin studies
• Identical (monozygotic) twins have identical
  genetic makeup.
• Fraternal (Dizygotic) twins are no more similar
  genetically than any other siblings.
• Twin studies are based on the assumption that
  identical twins should show greater similarity on
  any trait that is presumed to be inherited than
  fraternal twins.

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Genetic influences

• Identical twins twice as likely as fraternal
  twins to be similar in degree of criminal
  activity.
• Christiansen 7000 twins born in Denmark
  1881-1910
• 35 identical vs. 13 fraternal showed similarity
  in serious criminal activity
• Problems
• 65 identical twins did not have similar records
• Identical twins may have more similar
  environments than do fraternal twins.

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Genetic/biological vs. environment

• Debate
• Aggressive behavior results from an interaction
  between genetic/biological factors and
  environmental factors, but aggression is more
  powerfully influenced by genetic and/or
  biological factors.
• Aggressive behavior results from an interaction
  between genetic/biological factors and
  environmental factors, but aggression is more
  powerfully influenced by environmental factors.

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Heredity vs. environment

• Example Serial killer, Joel Rifkin
• Researchers examine both environment and possible
  genetic basis (look at brain scans)
• Video clip discussion
• To what extent do you think that Joel Rifkins
  killing was caused by genetic/biological factors
  or environmental factors?