Study Notes

The Biological Approach

AS, A-Level
AQA, Edexcel, OCR, IB

Last updated 5 Sept 2022

The biological approach attempts to explain behaviour as the direct product of interactions within the body.

Key assumptions of the biological approach

  • There is a direct correlation between brain activity and cognition
  • Biochemical imbalances can affect behaviour
  • Brain physiology can affect behaviour
  • Behaviour can be inherited (as it is determined by genetic information)

Evolution and the genetic basis of behaviour

Charles Darwin’s publication – On the Origin of Species (1859) – described the process of natural selection; characteristics that are not suited to a species’ environment will die out as it struggles to survive, and with time will evolve over generations so that only adaptive characteristics remain in future offspring.

Genes are the genetic information carried by DNA in chromosomes, found within a cell’s nucleus; they are passed on through generations of a species if individuals survive and successfully reproduce. In line with Darwin’s theory of evolution, it might also follow that genes form a basis of behaviour, as both behaviour and genes appear to be heritable. An example might be aggressive behaviour, in light of obvious survival benefits such as warding off predators and competing for resources.

Nature-nurture debate

The genotype describes the genetic configuration of an individual, whereas phenotype describes the combined effects of genetic makeup and surrounding environment on behaviour. The nature-nurture debate highlights a key argument in psychology, over the relative influence of biology and environment on the characteristics of an individual; an extreme biological approach assumes that these are determined solely by nature.

Effects of brain physiology and neurochemistry

Interactions between regions of the brain help to control different functions, which biological psychologists assume to be significant in determining our actions. For instance, the occipital lobe is involved heavily in processing sight, along with the frontal lobe, which is thought to be involved in control and attention.

Electrical impulses enable an important means of internal communication that directs our behaviour, travelling around the brain and to/from the body via the nervous system. Impulses are transmitted between neurons (nerves) at synapses, junctions where neurotransmitters are released that inhibit or excite other neurons to achieve different responses. Neurochemical imbalances in the brain are often associated with abnormal behaviour – for instance, evidence suggests that imbalances of dopamine (a neurochemical linked with the brain’s natural ‘pleasure’ system) are associated with mood disorders such as depression.

The endocrine system is a slower-acting communication system that regulates the circulation of hormones, released by glands into the bloodstream. For example, cortisol and adrenaline are key hormones that facilitate the fight or flight response, a key evolutionary survival mechanism whereby the body primes itself for imminent danger (e.g. increasing heart rate, initiating sweating to cool down, dilation of pupils, sharpened sense of hearing).

Research methods used by the biological approach

Animal studies – used to investigate biological mechanisms that govern human behaviour, often where ethical guidelines would not allow human participation. Many species (e.g. rats) are thought to have a similar biological makeup to humans, such that studies’ conclusions can be generalised to humans. However, this methodology still raises ethical debate, and some argue that complex human behaviour cannot be replicated in non-human animals like rats, and thus cannot be investigated.

Case studies – can investigate normal behaviour by observing behavioural abnormality alongside corresponding changes in biology. A very early example is the apparent personality alteration observed in Phineas Gage (mid 1800s) after a railroad construction accident drastically changed his physiology by forcing an iron rod through his brain’s frontal lobe.

Drug therapy – behaviour can be manipulated by altering an individual’s biochemistry, a research method that can ultimately lead to developing drug applications to improve health and wellbeing. Initial phases of research are usually conducted on non-humans.

Scans – physiology and activity across the brain can be gauged using various techniques (e.g. MRI, PET, CAT), helping researchers to identify the functions of specific regions (known as localisation of cortical function).

Twin/family studies are useful for investigating the heritability of behaviour. For instance, research can investigate the likelihood that both of two twins develop a characteristic, known as a concordance rate. However, these studies can be time-consuming, due to long delays often required before follow-up data is collected. It is also difficult finding a large samples of participants for twin studies.

Example: Evidence has suggested that if one identical twin (monozygotic [MZ], with near-identical genetic information to the other) develops schizophrenia, there is a roughly 48% chance of the other also developing schizophrenia, whereas this is only about 17% with non-identical twins (dizygotic [DZ], who share about 50% of their genes). Such findings support that genetics play a significant part in the disorder.

Evaluation of the biological approach


  • Scanning research techniques are useful for investigating the functions of the brain: an organ with obvious involvement in our behaviour that would otherwise be unobservable.
  • The approach presents the strong nature viewpoint of the nature-nurture debate.
  • The experimental methods used (gathering empirical [i.e. observable] evidence) make this approach very scientific.


  • The approach is considered reductionist; complex behaviour, thoughts and emotions are all equally explained by low-level biological mechanisms such as biochemicals and nerve impulses.
  • Biology alone has been unable to explain the phenomenon of consciousness.
  • An extreme biological approach does not account for the wide base of evidence that points to the influence of our environment (e.g. culture and society).

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