Aggression = intentional behavior aimed at causing physical or psychological pain.
o Types of Pain:
Physical Aggression = Aggression inflicting physical pain.
Verbal or Relational Aggression = Saying or doing psychologically
o Goal of Pain:
Hostile Aggression = Aggressive behavior that stems from feelings of
anger and has the goal of inflicting pain.
Instrumental Aggression = Inflicts pain and the pain is a middle step
toward another goal.
Approaches to Aggression
o Genetic Predisposition – Basic theoretical premise: aggression is adaptive and
has survival value. Earliest evidence: animals can be bred for aggression and
twin studies find high heritability for aggression.
Stimulating amygdala can lead to aggression.
Depends on context:
o Sometimes leads to withdrawal/fear
o Relative social status matters
Higher status = aggression
Lower status = withdrawal/fear
Pre Frontal Cortex
Generally involved in planning and behavioral regulation.
PFC may be the regulator of aggressive impulses.
Murderers have less PFC activity than normal controls.
PFC becomes activated when contemplating an aggressive act.
The steroid hormone testosterone may increase aggression.
o Smaller 2D:4D ratios correlated with greater exposure
to androgens (prenatal testosterone) in the womb.
o Smaller 2D:4D ratios correlated with aggression.
o 'The Finger Ratio' how the ratio of the index finger and
ring finger (= the '2D:4D digit ratio' finger length)
***Look at slide 15 for image or 2D:4D ratio***
o Injecting testosterone does not increase aggression
o Testosterone-aggression has a small effect size, r=0.14
Neurotransmitter related to many aspects of experience
May inhibit aggressive impulses
o Violent criminals have less serotonin than normals
o Serotonin antagonists (blockers) increase aggression
o Chemical Influence: Alcohol
Alcohol disinhibits behavior in general