PSY100H1 Lecture Notes - Lecture 16: Appeasement, Brain Tumor, Amygdala

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Published on 17 Apr 2013
Lecture 16 notes
Aggression in Humans and Animals
- Data on within-species (intraspecific) murders show that humans tend to kill their own more
than any other species of animal
- Konrad Lorenz distinguished between two types of species of animals. There are those animal
that are naturally equipped with ways to kill (lions-teeth, claws) and there are those that are not
so equipped (birds)
- According to Lorenz, during the process of evolution, those animals that were naturally
equipped learned to inhibit the use of their power to kill their own species. Instead they used
their abilities in other ways (hunting, threatening, ritualized fighting)
- Another inhibition has to do with appeasement gestures, they often take the form of submission
- Humans are not naturally equipped with the ability to kill each other easily
- We have advanced cognitive skills. These skills have allowed us to develop weapons
- Lorenz suggested that since humans have acquired means to kill each other and do not have
strong inhibitions about killing members of their own species, they tend to kill each other more
than other animals
Aggression and the Brain
- There are areas of the brain that seem directly responsible for aggression in animals
- When electrodes are inserted in the hypothalamus or the amygdala, and these areas are
stimulated with very low current, the animal becomes immediately aggressive
- Clinical studies with humans have also shown that brain tumours that cause pressure on the
amygdala and hypothalamus can cause the patient to be extremely violent
Aggression Impulsive or Controllable?
- Stimulating the hypothalamus and the amygdala in the monkey brain causes aggression
- When the stimulated monkey is in a cage with another monkey of equal or lower strength, the
stimulated monkey will attack
- When the other monkey in the cage is more dominant, the stimulated monkey will flee instead
of aggressing
- Even if aggression is impulsive, it appears to be influenced by cues in the environment
Males more aggressive than Females?
- Males do indeed engage in more aggressive acts than females
- When females are provoked, they aggress as much as men
- Men are more likely to engage in direct aggressive behaviour
- Females are more likely to engage in indirect aggression such as spreading vicious rumours and
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