Biological approach to understanding behaviour
Biological approach to understanding behaviour
The biological approach explains behaviour through physiology: genes, brain structure and function, neurotransmitters and hormones. HL papers test your ability to describe and evaluate research evidence, apply biological explanations to real behaviour, and discuss ethical considerations. An SAQ usually asks about one concept; an ERQ asks you to compare or evaluate at least two.
Core rules and concepts
- Genetics: twin, family and adoption studies; concordance rates; heritability; genotype vs phenotype. Candidate genes (for example, 5-HTT) are associated with, not determinative of, behaviour.
- Brain: localisation of function (HM's hippocampus), neuroplasticity (Maguire's taxi drivers), and scanning methods (fMRI, PET) support structure–function claims.
- Neurotransmitters: serotonin, dopamine; agonists and antagonists are used to test causal claims.
- Hormones: cortisol, testosterone, oxytocin; effects are often bidirectional and context-dependent.
- Ethics: animal research, informed consent, and the risk of biological determinism.
Worked example
Maguire et al. (2000) compared London taxi drivers with controls and found larger posterior hippocampi, correlated with years of driving. Reasoning: a structural difference linked to navigation experience supports neuroplasticity. But the design is cross-sectional and correlational: the hippocampus could have been larger before training, so causation is not established. Evaluation should therefore credit the finding while noting self-selection and the lack of a longitudinal control. This structure - finding, inference, limitation, counter-claim - is what earns ERQ marks.
Traps that cost marks
- Treating heritability as "percentage genetic" or as destiny.
- Reporting a correlation as proof that a brain area causes a behaviour.
- Describing a study without linking it to the question's concept.
- Ignoring ethical considerations when the prompt asks for evaluation.
- Confusing neurotransmitters with hormones, or agonist with antagonist.