The Unconscious

The Biological Approach

The biological approach proposes that all behaviour, thought, and emotion has a biological basis — that to understand psychology we must understand the body and brain that produce it. The approach emphasises the roles of genetics, neurochemistry, brain structure, and evolution in determining behaviour, and argues that psychological disorders and individual differences can ultimately be explained in biological terms.

Genes and Behaviour

The biological approach proposes that behaviour is significantly influenced by genetic factors. Genes — sequences of DNA that code for the production of proteins — influence the development of the nervous system, the production of neurotransmitters, and the sensitivity of receptors, all of which shape behaviour. The distinction between genotype (the individual's complete set of genetic information) and phenotype (the observable expression of genes in physical characteristics and behaviour) is important: genes do not directly produce behaviour — they influence the biological structures and processes that produce behaviour, and their expression is modulated by environmental interactions.

Evidence for genetic influences on behaviour comes from twin studies (MZ-DZ concordance comparisons), adoption studies (comparing adopted children with biological and adoptive parents), and increasingly from molecular genetics (identifying specific genes or gene variants associated with traits and disorders). Heritability estimates for characteristics such as intelligence, personality traits, and many mental disorders typically fall in the range 40–80%, indicating substantial but not total genetic influence.

Biological Structures

The biological approach emphasises the role of specific brain structures and neural circuits in behaviour. Different brain regions are associated with different psychological functions: the amygdala with fear and emotional memory; the hippocampus with memory formation; the prefrontal cortex with decision-making, planning, and impulse control; and the hypothalamus with regulation of hunger, thirst, and arousal. Damage to or dysfunction of specific structures — through brain injury, stroke, or degenerative disease — produces characteristic changes in behaviour, providing evidence for localisation of function.

Neurotransmitters — chemical messengers that carry signals across synapses — also play a crucial role. Imbalances in specific neurotransmitters are associated with psychological disorders: low serotonin with depression and OCD; excess dopamine with schizophrenia; imbalances in noradrenaline with anxiety and depression. Drugs that alter neurotransmitter availability (antidepressants, antipsychotics, anxiolytics) are effective treatments, providing pharmacological evidence for neurochemical accounts.

Evolution and Behaviour

The biological approach draws on Darwin's theory of natural selection to argue that many human behaviours have an evolutionary basis. Behaviours that enhanced survival and reproductive success in the environment of evolutionary adaptation (EEA) were naturally selected — they increased in frequency across generations because individuals carrying the genetic variants associated with them reproduced more successfully. This evolutionary perspective proposes that human behavioural tendencies — including attachment behaviour, aggression, mate selection preferences, and fear of certain stimuli — reflect adaptations to ancestral environments rather than purely cultural learning.

Evaluation

The biological approach has strong scientific credentials — it uses objective, reliable measurement methods (brain imaging, genetic analysis, pharmacological challenge studies) and has generated effective treatments for many psychological disorders. However, it has been criticised for biological reductionism: reducing complex psychological phenomena to biological processes risks ignoring the role of social, cultural, and cognitive factors. The approach tends towards determinism — implying that behaviour is fixed by biology — which has ethical implications and ignores human agency. Evolutionary explanations are often criticised as unfalsifiable and post hoc — constructed to explain observed behaviour after the fact rather than making genuine predictions in advance.