Aggression
Notes
Paper 3 - Section D
,Aggression
Many different types of aggression - hard to define
Problem that aggression involves intent to harm - hard to be sure of one's intentions
Psychologists try to understand aggression by looking at it as 2 types of behaviour
1. Proactive - ‘cold blooded’, planned method of getting what you want
2. Reactive - ‘hot blooded’, impulsive reaction, combined with physiological arousal
What psychologists are most interested in ( responsible for more social problems)
Aggression:
- By product of complex internal physiological processes
- Caused by underlying biological processes
- Or by learning / the environment
,Biological explanations of aggression
Neural mechanisms
Neuroanatomy
- The structure of certain parts of the brain causes aggression
- Interaction between different systems of the brain (not just one area)
- Focus on the role of the limbic system / how it’s regulated by the prefrontal cortex
The Limbic System
● System of structures lying beneath the cortex (including the amygdala)
● Helps coordinate behaviours that satisfy motivational / emotional urges
Amygdala
● Part of the limbic system which has long been linked with expression of emotion
● Its function is to control fear responses, the secretion of hormones, arousal and the
formation of emotional memories - has been implicated in aggressive behaviour
★ High activity levels (hyperactivity) in the amygdala may be linked to aggression
★ Reduced amygdala volume is also associated with aggression
Evaluation of the amygdala / limbic system
LeDoux: lab rats
● Electrical stimulation of the amygdala produced fear and rage on lab rats
● Supports amygdala's role in aggressive behaviour (result of direct stimulation)
● BUT, Eager and Flynn found stimulation of the amygdala would increase or
decrease aggression, depending on the region stimulated
Mark & Ervi
● Julie suffered from epilepsy - fits / violent behaviour
● Used electrodes placed on the amygdala to do deep brain stimulation
● When she played guitar and the amygdala was stimulated she began to smash it
● Replicated animal findings in humans - supports amygdala's role in aggression
● BUT it’s a case study - her epilepsy may act as an extraneous variable distributing
various normal brain functioning
Pardidni
● Longitudinal study of male p’s
● Found reduced amygdala volume measured using mRI scans at 26 can predict the
development of persistent aggressive behaviour
● Only carried out on males - do the results generalise to women? (beta bias)
● Confounding variables (drugs, abuse, neglect, brain trauma) considered / controlled
although other variables may still have had an effect
- Research provides evidence to support the role of amygdala in aggression
- But it is not a simple relationship, the amygdala is a complex structure involved in
different functioning → unlikely the amygdala alone results in aggression
, Prefrontal cortex (not part of the limbic system)
● The role of the PFC is to control outward signs of aggression
● Directly connects to the limbic system / regulates amygdala-driven emotion
responses forming part of our impulse/emotion control
● As a result the PFC depends on high levels of alertness and links with deeper brain
structures related to pleasure, pain, anger, rage, panic ( fight-flight-freeze response)
★ Suggestion that damage to / reduced activity (hypoactivity) in the PFC is linked to
aggressive behaviour as it results in loss of control, impulsivity, altered emotionality
Evaluation of the prefrontal cortex
Coccaro: Psychiatric patients
● Measured Brain Activity in 10 violent psychiatric p’s and 10 healthy controls
● The more active a brain area is, the more blood supply is required
● They found activity in the prefrontal cortex was reduced disrupting its impulsive
control function and this leading to increased violent behaviour
Raine: Murderers
● Assessed 41 murderers using PET scans
● They found reduced activity in the PFC of murderers compared to the controls
● Suggests hypoactivity in the PFC is associated with aggressive behaviour
● The controls were matched on age, sex..
● Objective evidence from PET scans: empirical, objective research can be replicated
increasing the scientific credibility
● Direction of causality: extraneous variables (childhood trauma) may cause abnormal
brain development and a predisposition to aggression - cannot test empirically
- Issues with the research as they rely on correlations
- However it dies show that the PFC plays a role in aggression (unlikely alone)
- Likely an interaction with other brain structures / biological / environmental factors
Notes
Paper 3 - Section D
,Aggression
Many different types of aggression - hard to define
Problem that aggression involves intent to harm - hard to be sure of one's intentions
Psychologists try to understand aggression by looking at it as 2 types of behaviour
1. Proactive - ‘cold blooded’, planned method of getting what you want
2. Reactive - ‘hot blooded’, impulsive reaction, combined with physiological arousal
What psychologists are most interested in ( responsible for more social problems)
Aggression:
- By product of complex internal physiological processes
- Caused by underlying biological processes
- Or by learning / the environment
,Biological explanations of aggression
Neural mechanisms
Neuroanatomy
- The structure of certain parts of the brain causes aggression
- Interaction between different systems of the brain (not just one area)
- Focus on the role of the limbic system / how it’s regulated by the prefrontal cortex
The Limbic System
● System of structures lying beneath the cortex (including the amygdala)
● Helps coordinate behaviours that satisfy motivational / emotional urges
Amygdala
● Part of the limbic system which has long been linked with expression of emotion
● Its function is to control fear responses, the secretion of hormones, arousal and the
formation of emotional memories - has been implicated in aggressive behaviour
★ High activity levels (hyperactivity) in the amygdala may be linked to aggression
★ Reduced amygdala volume is also associated with aggression
Evaluation of the amygdala / limbic system
LeDoux: lab rats
● Electrical stimulation of the amygdala produced fear and rage on lab rats
● Supports amygdala's role in aggressive behaviour (result of direct stimulation)
● BUT, Eager and Flynn found stimulation of the amygdala would increase or
decrease aggression, depending on the region stimulated
Mark & Ervi
● Julie suffered from epilepsy - fits / violent behaviour
● Used electrodes placed on the amygdala to do deep brain stimulation
● When she played guitar and the amygdala was stimulated she began to smash it
● Replicated animal findings in humans - supports amygdala's role in aggression
● BUT it’s a case study - her epilepsy may act as an extraneous variable distributing
various normal brain functioning
Pardidni
● Longitudinal study of male p’s
● Found reduced amygdala volume measured using mRI scans at 26 can predict the
development of persistent aggressive behaviour
● Only carried out on males - do the results generalise to women? (beta bias)
● Confounding variables (drugs, abuse, neglect, brain trauma) considered / controlled
although other variables may still have had an effect
- Research provides evidence to support the role of amygdala in aggression
- But it is not a simple relationship, the amygdala is a complex structure involved in
different functioning → unlikely the amygdala alone results in aggression
, Prefrontal cortex (not part of the limbic system)
● The role of the PFC is to control outward signs of aggression
● Directly connects to the limbic system / regulates amygdala-driven emotion
responses forming part of our impulse/emotion control
● As a result the PFC depends on high levels of alertness and links with deeper brain
structures related to pleasure, pain, anger, rage, panic ( fight-flight-freeze response)
★ Suggestion that damage to / reduced activity (hypoactivity) in the PFC is linked to
aggressive behaviour as it results in loss of control, impulsivity, altered emotionality
Evaluation of the prefrontal cortex
Coccaro: Psychiatric patients
● Measured Brain Activity in 10 violent psychiatric p’s and 10 healthy controls
● The more active a brain area is, the more blood supply is required
● They found activity in the prefrontal cortex was reduced disrupting its impulsive
control function and this leading to increased violent behaviour
Raine: Murderers
● Assessed 41 murderers using PET scans
● They found reduced activity in the PFC of murderers compared to the controls
● Suggests hypoactivity in the PFC is associated with aggressive behaviour
● The controls were matched on age, sex..
● Objective evidence from PET scans: empirical, objective research can be replicated
increasing the scientific credibility
● Direction of causality: extraneous variables (childhood trauma) may cause abnormal
brain development and a predisposition to aggression - cannot test empirically
- Issues with the research as they rely on correlations
- However it dies show that the PFC plays a role in aggression (unlikely alone)
- Likely an interaction with other brain structures / biological / environmental factors
