Specification: The influence of genes, biological structures and neurochemistry on behaviour. Genotype and phenotype, genetic basis of behaviour, evolution and behaviour.

Assumptions

• All thoughts, feelings and behaviours have a physical basis

• Behaviours are influenced by the genes we inherit

• Biological evolution allows us to understand the adaptive significance of behaviours, such as aggression, through natural selection

• Neurological structures (physiology and structure of the brain) influence behaviour

The biological approach

The biological approach assumes that all human behaviour has a biological origin. This approach insists that to comprehend human behaviour fully, it is necessary to understand internal biological structures and processes including genes, the nervous system, and neurochemistry.

The influence of neurochemistry

Biological psychologists also recognise the role of chemicals in determining behaviour. At the synapse, signals are sent between neurones by chemicals called neurotransmitters. Imbalances in the number of neurotransmitters are associated with atypical behaviour, for example, too little serotonin has been associated with depression and too much dopamine has been associated with schizophrenia.

Research in this area helps us to understand the role of neurotransmitters. For example, recent research suggests that abnormally low levels of serotonin are linked to aggressive behaviour, indicating that this neurotransmitter is important in regulating behaviour and impulse control (Crockett et al., 2008).

Other types of chemicals found in the body which can also influence behaviour are called hormones. They are released into the bloodstream where they travel to the target cells which are activated by them specifically. Carre et al., (2006) found that high levels of testosterone are associated with defensiveness and territoriality in a study investigating the behaviour of ice hockey players.

Evolution and behaviour

Genes are the mechanism through which evolution takes place. The process of natural selection, proposed by Darwin, ensures that characteristics which provide an evolutionary advantage, such as survival and enhanced reproductive chances, are passed from one generation to the next, whilst others which do not, die out.

A classic example of evolutionary psychology research is Buss’s (1994) survey of heterosexual mate selection. Across all 37 countries studied, he found that men preferred good looks, youth and chastity, while women preferred good financial prospects, industriousness and dependability. These results suggest that certain behaviours and traits have evolved in both males and females since they promote better prospects for passing on favourable genes.

Evaluation of the biological approach

One limitation of the biological approach is that causation is often strongly implied in explanations that focus on brain structures. For example, one explanation of schizophrenia suggests that a lack of activity in the ventral striatum is linked to the development of negative symptoms such as avolition. This is a problem for biological explanations because such research tells us only that there is an association between brain structures and behaviour; it cannot tell us that the reduced activity in that area of the brain causes the behaviour, or that the behaviour causes lower activity in that part of the brain. Therefore, it is critically important to remember that biological explanations are often based on correlational results, which does not mean that one event causes the other.

Another weakness of this approach is that biological explanations of human behaviour may be considered deterministic. For example, one assumption of the biological approach is that some human behaviours are the result of evolution: they maximise our chances of survival and reproduction and thus are ‘naturally selected’ and inherited from our ancestors. Such evolutionary claims are used to explain a variety of gender differences in human behaviour including aggression and stress. Such explanations imply that humans have little control over their behaviour, and suggest we are predetermined to act in a certain way regardless of experience, free will, or the environment. This is problematic for those who do not follow ‘typical’ or ‘expected’ behaviours and overemphasises the role of nature on behaviour. It is also an explanation that is unfalsifiable, and thus incapable of scientific validation.

However, a strength of the biological approach is that it often utilises reliable methods of research. For example, some research into genetics and neurochemistry requires precise scientific methodology, such as fMRIs, PET scans, drug trials, and EEGs. These techniques provide psychologists with an accurate measure of internal processes that were previously not accessible. This makes biological evidence less susceptible to misinterpretation or experimenter bias which is a strength of such research.

Another strength of the biological approach is that it has many real-world applications. Drug therapies have been developed for many mental illnesses based on research into neurotransmitters; antidepressants work to increase serotonin levels in the brain, based on the understanding of how low levels of serotonin contribute to depressive symptoms. Understanding ‘abnormal’ neurochemical activity in the brain has not only been helpful for developing treatments but has also provided patients with an explanation that their illness is not their fault.

Issues and debates

In order for complex human behaviour to be analysed and best understood, according to biological psychologists, it must be broken down into its component parts. This means that phenomena are explained using genetic, neurochemical or structural explanations resulting in the biological approach taking a reductionist (biological) perspective.

Whilst it is widely accepted that the biological approach takes the nature side of the nature-nurture debate, since behaviour is determined by innate features including genes and neurotransmitters, acknowledgement is paid to the role of the environment with the interaction of the two influencing an individual’s phenotype.

Possible exam questions

1. Identify which of the following describes a phenotype. Shade one box only. (1 mark)

A The influence of genotype and evolution.

B The impact of genetic makeup intertwined with neurotransmitters.

C An interaction between inheritance and the environment.

D A combination of neurotransmitters and environment.

2. Identify which one of the following statements about evolution is incorrect by shading one box only. (1 mark)

A Evolution involves those humans best suited for survival breeding together.

B The process of evolution involves adaptation.

C Through evolution, behaviour is changed from one generation to the next.

D Evolution suggests that species have genetic material in common.

3. Explain what is meant by the term evolution with reference to human behaviour. You may provide an example to support your answer. (3 marks)

4. Briefly describe the influence of genes on behaviour. (3 marks)

5. Using an example to illustrate your point, explain the difference between genotype and phenotype. (3 marks)

6. Define what is meant by genotype and phenotype. Provide an example for each. (4 marks)

7. Monozygotic (identical) twins, Ikhlas and Vinay, were separated at birth. On their fortieth birthday, they finally met up with one another. Whilst they were talking, they realised that they had very different personality traits: Ikhlas is very sociable whereas Vinay is more introverted.

Using your knowledge and understanding of genotype and phenotype, explain the personality differences of Ikhlas and Vinay. (4 marks)

8. Explain the influence of biological structures on human behaviour. (4 marks)

9. Explain one strength and one limitation of the biological approach in psychology. (6 marks)

10. Discuss the biological approach in psychology. (16 marks)

11. Discuss the biological approach to explaining human behaviour. Include at least one comparison to another approach in psychology in your response. (16 marks)