Biopsychology and aggression: brain structures, neurotransmitters, hormones and genes in aggression, evolutionary and learning explanations, and the named aggression studies.

What this dot point is asking

Edexcel wants you to explain aggression through brain structures, neurotransmitters, hormones, genes and evolution, contrast this with learning explanations, and use named aggression studies as evidence. The exam reward is an interactionist conclusion rather than picking a single cause.

The answer

Brain structures and neurotransmitters

Hormones and genes

Evolutionary and learning explanations

Evaluation (GRAVE)

• Generalisability. Animal aggression studies and clinical samples (such as Raine's insanity-plea murderers) may not generalise to ordinary human aggression.
• Reliability. Physiological measures (PET scans, hormone assays) are standardised and objective, giving reliable, replicable data.
• Application. Understanding the biology of aggression informs treatment (drugs to manage impulsivity) and risk assessment, a real-world benefit, though it raises ethical concerns about labelling.
• Validity. Most biological evidence is correlational, so it cannot prove that brain, hormone or gene differences cause aggression; reverse causation and third variables are possible.
• Ethics. Biological accounts risk biological determinism and the idea of a "born criminal", which has serious implications for responsibility and the justice system.

Examples in context

Example 1. Raine et al. (1997) and reduced prefrontal activity. Raine's PET-scan study of 41 murderers found reduced activity in the prefrontal cortex compared with matched controls. Because the prefrontal cortex normally inhibits impulsive and aggressive responses, reduced activity there fits the idea that a weakened "brake" allows aggression to break through. This is the named biological aggression study Edexcel rewards. The evaluation is that it is correlational (the brain differences could be a consequence rather than a cause), uses an unusual legal sample, and does not consider learning or social factors, so it cannot be a complete explanation.

Example 2. Bandura's Bobo doll study (social learning of aggression). Children watched an adult model behave aggressively towards an inflatable Bobo doll (hitting, kicking, shouting). When later left with the doll, children who had seen the aggressive model imitated specific aggressive acts far more than children in a non-aggressive or control condition, and boys imitated physical aggression more than girls. A later variation showed vicarious reinforcement mattered: children imitated more when the model had been rewarded. This is strong evidence that aggression can be acquired through observation and imitation, an environmental explanation that complements the biological account and supports an interactionist conclusion.

Try this

Q1. Explain the role of the amygdala and serotonin in aggression. [4 marks]

• Cue. The amygdala processes threat, so overactivity increases aggressive responses; serotonin inhibits impulses, so low serotonin reduces control and increases impulsive aggression.

Q2. Outline one evolutionary explanation of aggression. [2 marks]

• Cue. Aggression was adaptive because it helped ancestors gain or defend resources, territory and mates, so the trait was naturally selected and inherited.

Q3. Assess the view that aggression is best explained by biological factors. [8 marks]

• Cue. Present brain, neurotransmitter, hormone and gene evidence (Raine, MAOA), then weigh against social learning (Bandura) and the correlational, deterministic and reductionist limits of biology; conclude in favour of an interactionist account.