The Biological Approach (AQA A-Level Psychology): Revision Notes
The Biological Approach
The biological approach operates on the principle that all human behaviour stems from biological origins. This perspective emphasises that to fully understand human behaviour, we must examine internal biological structures and processes, including genes, the nervous system, and neurochemistry.
This foundational approach in psychology suggests that every aspect of human behaviour can be traced back to biological mechanisms, making it essential to study the body's internal systems to understand psychological phenomena.
The influence of genes: genotype and phenotype
Genotype refers to a person's genetic makeup, which remains fixed from birth. Phenotype describes how these genes are expressed, creating the observable characteristics we can see in a person. The phenotype results from both genetic inheritance and environmental interactions.
Researchers in this field examine how behavioural and psychological characteristics, including intelligence and mental illness, can be inherited similarly to physical traits like eye and hair colour. Monozygotic (MZ) twins provide particularly valuable research opportunities because they share 100% of their DNA (identical twins), compared to dizygotic (DZ) twins who share only 50% of their DNA.
Research evidence
Twin studies have revealed important patterns in genetic influence on behaviour. For instance, MZ twins show higher concordance rates for developing schizophrenia compared to DZ twins.
Research Example: Twin Studies and Depression
McGuffin et al. (1996) discovered that when one identical twin experiences depression, there is a 46% probability that the other twin will also develop depression. This research demonstrates a genetic component in psychological conditions and highlights how genes impact human behaviour.
The influence of biological structures
Biological psychologists argue that organ structures, particularly the brain, central nervous system (CNS), peripheral nervous system (PNS), and endocrine system, determine our behaviour patterns. The nervous system transmits messages through specialised nerve cells called neurons.
Different brain regions control various behaviours, including basic functions like eating responses (hunger and satiation) and breathing. This localisation of function allows researchers to study specific brain-behaviour relationships.
Research has identified that specific brain lobes connect to particular functions - the occipital lobe processes visual perception, whilst the parietal lobe handles sensory information processing.
Case study evidence
Case Study: Phineas Gage
The famous case of Phineas Gage powerfully demonstrates how biological structures influence behaviour. After an explosion sent an iron bar through his head, destroying a substantial portion of his frontal cortex, Gauge lost his ability to control antisocial behaviour. This case study clearly shows how biological structures (specifically the frontal cortex) directly impact behavioural control and inhibition.
The influence of neurochemistry
Biological psychologists recognise that chemicals play a vital role in determining behaviour. At synapses, signals transfer between neurons through chemicals called neurotransmitters. Imbalances in neurotransmitter levels correlate with unusual behaviour patterns. Insufficient serotonin links to depression, whilst excessive dopamine associates with schizophrenia.
Critical Connection: Neurotransmitter Imbalances
Understanding the relationship between neurotransmitter levels and behaviour is essential - these chemical imbalances don't just correlate with psychological conditions, they may be fundamental to understanding how biological processes create behavioural patterns.
Research advances our understanding of neurotransmitter functions. Crockett et al. (2008) found that abnormally low serotonin levels connect to aggressive behaviour, suggesting this neurotransmitter helps regulate behaviour and impulse control.
Hormones represent another category of influential body chemicals. These substances enter the bloodstream and travel to target cells, activating them for specific functions. Carre et al. (2006) discovered that elevated testosterone levels correlate with increased defensiveness and territorial behaviour in ice hockey players.
Evolution and behaviour
Genes serve as the mechanism through which evolutionary processes occur. Natural selection, Darwin's proposed process, ensures that advantageous characteristics promoting survival and reproductive success transfer from one generation to the next, whilst disadvantageous traits gradually disappear.
Research Example: Evolutionary Mate Selection
Buss's (1994) research on heterosexual mate selection across 37 countries exemplifies evolutionary psychology research. His findings revealed that men preferred physical attractiveness, youth, and chastity, whilst women valued financial prospects, industriousness, and dependability. These results suggest that specific behaviours and preferences have evolved in both sexes because they enhance genetic transmission prospects.
Evaluation of the biological approach
Weaknesses
Major Limitation: Causation Problems
Causation problems represent one major limitation of the biological approach. Explanations focusing on brain structures often strongly imply causation inappropriately. For example, schizophrenia explanations sometimes suggest that reduced ventral striatum activity causes negative symptoms like social withdrawal. However, biological explanations typically rely on correlational evidence, which cannot establish that brain structure changes cause behavioural changes, or that behavioural patterns cause brain activity changes.
Therefore, biological explanations must be interpreted carefully as associations rather than direct causal relationships.
Philosophical Concern: Deterministic Implications
Deterministic implications present another concern with biological explanations of human behaviour. The approach sometimes assumes that human behaviours result from evolutionary processes that maximise survival and reproduction chances, suggesting these behaviours are 'naturally selected' and inherited from ancestors.
Such evolutionary arguments attempt to explain gender differences in behaviour, including aggression and stress responses. These explanations imply that humans have limited behavioural control and are predetermined to act in specific ways regardless of personal experience, free will, or environmental factors. This perspective becomes problematic for individuals who do not display 'typical' or 'expected' behaviours and overemphasises nature's role in behaviour. Additionally, these explanations cannot be scientifically validated, making them unfalsifiable.
Key Points to Remember:
- The biological approach assumes all behaviour has biological origins, requiring understanding of genes, brain structures, and neurochemistry
- Twin studies using MZ and DZ twins help demonstrate genetic influences on behaviour and psychological conditions
- Brain structures like the frontal cortex control specific behaviours, as demonstrated by cases like Phineas Gauge
- Neurotransmitters (serotonin, dopamine) and hormones (testosterone) significantly influence behaviour patterns
- The approach faces criticism for implying causation from correlational data and promoting deterministic views of human behaviour