Explanations of aggression

• Brain structure and aggression:

  • The pre frontal cortex is involved in aggression- the oribital forntal cortex plays an important role in higher cognitive functions such as rational thinking and decision making, thought to be involved with self control and with patients with psychiatric disorders that feature aggression, activity in the OFC is reduced
  • has a lot of connections with parts of the brain relating to dopamine and serotonin
• The limbic system and aggression:

  • includes the hippocampus, amygdala and hypothalamus- our most basic urges and desires are regulated
  • Hypothalamus- is about putting the body back into balance and regulates our hunger and thirst as well as our response to pain and anger.
  • Hippocampus- important role in taking STM and converting them into LTM
  • Amygdala- takes information from the thalamus and interprets as a threat or not, producing fear or aggression. If it malfunctions then things which are threatening will not produce a fear response OR harmless events will be interpreted as a threat
• Strength of the limbic system explanation of aggression:

  Pardini 2014 found that men over 20 years had behaved aggressively including acts of criminal violence and using fMRI scans the researchers found a strong negative correlation between levels of aggression and amygdala volumes- all confounding variables were controlled in the study so it MUST have been amygdala volumes causing behaviour
• Weakness of the limbic system explanation of aggression:

  MOST research is correlational so it is impossible to establish wether a particular structure or function is a cause of effect of aggressive behaviour as unsure is a third variable is involved
• Evolutionary explanation and aggression: natural selection

  • Natural selection is the choosing done by the environment of individuals who can survive and reproduce successfully
  • The 'fittest' are those who have characteristics that best match the demands of the environment - which occurs when there is competition for scarce resources
  • genes that are most useful are retained in population resulting in adaptation
  • the outcome of selection is adaptation
• Evolutionary explanation and aggression: sexual selection


  • sexual selection is the influence of evolution acting on the success of reproduction-traits which seem disadvantageous are attractive to potential mates
  • being able to protect you and your possessions enhance survival and reproduction- mate retention strategies are aggressive that men use to prevent mates from straying whilst also guarding their offspring to further reproduction so that the men can pass in their genes
  • aggression can be seen as a survival trait
• Credibility of Darwin's theory of natural selection

  It is a well established scientific theory with a huge amount of supporting evidence, modern science has identified the role that many genes play in hereditary features. The theory that brain structures or processes that enhance fitness will be passed on as survival traits is logical and matches with what is observed in animal and human studies.
• Strength of evolution as an explanation:

  It can explain why MALES are more aggressive that females. As females who are cooperative are likely to be naturally selected as it helps them protect themselves and their offspring as a group- therefore reduced aggression is selected in females. WHERE AS, males who are aggressive are more likely to be naturally selected because they make better hunters- strength as it explains gender differences in aggression today
• Supporting evidence of evolutionary explanation:

  Manson and Wrangham
• Weakness of evolutionary explanation:

  CANNOT explain cultural differences in aggressive behaviour- for example amoungst the Kung San people of the Kalanhari aggression is discouraged from childhood and is therefore RARE. In contrast the Yanomami of Brazil have been described as the 'fierce of people' where aggression appears to be an accepted behaviour to gain status on society .
• Testability of evolution as an explanation for aggression

  It is impossible to test evolution directly, which is why most resarch is correlational such as finding assosiations between mate retention behaviours and aggression. Correlational method does not allow us t draw cause and effect conclusions because variables are just measured not manipulated or controlled thus never ruling out the effects of other factors on aggressive behaviour.
• Brain function and aggression: role of neurotransmitters

  • Serotonin is a neurotransmitter with widespread inhibitory (less likely to fire neurone) effects on transmission between neuron's in the brain- slows down neuronal activity
  • normal levels of serotonin in the OFT are associated with a reasonable degree of behavioural self-control
  • decreased serotonin activity may disturb this link reducing self control leading to impulsive behaviours- aggression
• Brain function and aggression: role of neurotransmitters

  • Dopamine has inhibitory effects in some areas of the brain and exhibitory in others
  • it is involved in regulating motivated behaviour and our experiences of rewards
  • dopamines main influence on aggression is due to its interaction with serotonin- as serotonin under activity stimulates dopamine overactivity and both are linked to impulsivity and aggression
  • Therefore serotonin hypofunction is the primary cause of impulsive aggression and dopamine hypofunctions contributes
• supporting evidence for role of neurotransmitters in aggression:

  Virkkhunen 1994 compared levels of serotonin breakdown product in the cerebrospinal fluid of violent impulsive and violent non impulsive offenders, levels were significantly lower in those impulsive.
• Hormones and aggression:

  • The endocrine glands manufacture a variety of hormones
  • male sex hormone testosterone is heightened at puberty when males start experiencing facial hair ect
  • Testosterone can has a role of regulating social behaviour through its influence on areas in the brain such as the frontal cortex and amygdala which are associated with aggression
  • Testosterone works with cortisol as low levels of cortisol inhibits aggression by increasing testosterone levels- increasing aggression
• Supporting evidence for hormones as an explanation of aggression:

  Dabbs and Hargrove 1997 found a positive correlation between the hormone testosterone and the degree of violent crime in 87 female prisoners- it plays a role in aggression
• Conflicting evidence for role of hormones in aggression:

  Data tends to be correlational which limits cause and effect conclusions to be drawn and the role of other transmitters may be involved which limits how we can treat aggressive offenders
• Freuds psychodynamic explanation: role of unconscious

  • The unconscious is the part of the mind containing thoughts, memories and desires which WE ARE UNAWARE
  • key influence of the unconscious is its role as the origin of powerful aggressive instincts- even if we are not thinking of aggressive thoughts out behaviour still may be influenced by aggressive urges in the unconscious
• Freuds psychodynamic explanation: Personality

  • The ID- contained entirely in the unconscious, origin of the energy that motivated all our behaviour including aggression. Obeys the pleasure principle- making aggression unavoidable
  • The EGO- is logical+rational following the reality principle- the interface between the unrealistic desires of the id and social reality. So the ego does not fulfill the ids aggressive urges
  • The SUPEREGO- fulfils the moral role that emerges later in development that represents our conscience and moral sense of right and wrong and opposes the ids aggressive drive
• Freuds psychodynamic explanation: Catharsis

  according to freud aggression is an instinctive drive that can be satisfied by catharsis- expressing aggression by venting anger as it relases psychic energy reducing the aggressive drive preventing further aggression

  preventing this creates a build up of energy which will eventually produce a destructive aggressive outburst which is either directed inwards- self harm or outwards- assult
• Testability of Freuds explanation of aggression:

  • His concepts are NOT measurable and cannot be rigorously tested due to them being based on qualitative data - for example the unconscious is unreachable by normal means and the id, ego and super ego cannot be measured so there is a lack of SCIENTIFIC CREDIBILITY
• Applying Freuds ideas:

  • Catharsis can be used practically to prevent a build up of destructive aggressive energy - which are based on Freuds concepts such as displacement such as hitting an object not a person. Catharsis could be featured in therapy - offering a practical solution to reduce aggressive behaviour with potential benefits for individuals and society
• Weakness of Freuds explanation:

  • Bushman made 600 college students angry by getting a confederate to criticise aqn essay they wrote. It was found that these students blasted the confederate with the loudest noises in a subsequent task AFTER already venting anger by hitting a punch bag- opposite of freuds theory as venting anger did not reduce aggression