by Paul Burkhart
Chapter 5 defined aggression as physical or verbal behavior intended to hurt
This excludes auto accidents, dental treatments, sidewalk collisions, and
It includes slaps, direct insults, even gossipy “digs,” and by having
people decide how much to hurt someone, such as how much electric shock to impose.
aggression, characterized by displays of rage, and
aggression, as when a predator stalks its prey.
Social and silent aggression involve
separate brain regions.
In humans, psychologists label the two types “hostile” and
Hostile aggression springs from anger, its goal is to injure.
Instrumental aggression aims to hurt only as a means to some other end.
Approximately half erupt from arguments, while others result from romantic
triangles or brawls under the influence of alcohol or narcotics.
Freud speculated that human aggression springs from a self-destructive impulse.
It redirects toward others the energy of a primitive death urge, which he called the “death
This follows the theory that aggressive energy is instinctual (unlearned and
If not discharged, it supposedly builds up until it explodes or until an
appropriate stimulus “releases” it, like a mouse releasing a mousetrap.
focus on releasing aggressive tendencies helps explain why more people were killed in
twentieth century wars than in all prior wars.
The idea that aggression is an instinct
collapsed as the list as supposed human instincts grew to nearly 6,000 in 1924.
Social scientists had tried to explain social behavior by naming it.
Instinct theory also
fails to account for variations in aggressiveness from person to person or culture to
Because aggression is a complex behavior, no one spot in the brain controls it.
But researchers have found neural systems in both animals and humans that facilitate
When the scientists activate these areas in the brain, hostility increases; when
they deactivate them, hostility decreases.
Docile animals can thus be provoked into rage,
and raging animals into submission.
Scientists have found that the prefrontal cortex,
which acts like an emergency brake on deeper brain areas involved in aggressive
behavior, was 14 percent less active than normal in nonabused murderers and 15 percent
smaller in the antisocial men.
As other studies of murderers and death-row inmates
confirm, abnormal brains can contribute to abnormally aggressive behavior.
Heredity influences the neural system’s sensitivity to aggressive cues.