Biological Approach

Main assumptions

Everything psychological is at first biological.
Therefore, to fully understand human behaviour we must look at biological structures and processes within the body (genes, hormones, neurochemistry and the nervous system)
Biological psychology tries to explain how we think, feel and behave in terms of physical factors within the body.
The mind lives in the brain (in contrast to the cognitive approach sees mental processes of the mind as being separate from the physical brain)

The key things you need to know within this approach are:

Genetics – genotype and phenotype
Evolution of behaviour
Biological structures
Cognitive neuroscience

Genes

Physical characteristics such as hair and eye colour are determined by our genetics. Can psychological traits such as intelligence and personality also be caused by our genes? Biological psychologists would argue that they are.

Genetic evidence from twins studies

Inheritance of characteristics is often tested by comparing the similarity of twins. Monozygotic twins (MZ) shares 100% of their genetic make-up. If a characteristic such as depression is entirely genetic we would expect that if one twin develops depression the other will too. We would say that there is a 100% concordance rate. Concordance rates: this is a term used to describe the rate of agreement, expressed as a percentage. For example, research has found that MZ twins have a concordance rate of 68% for OCD – this means if one twin had OCD, then 68% of the time the other twin also had OCD. DZ twins had a 31% concordance rate.

However, in practice, no psychological disorder has a 100% concordance rate. The highest appears to be bipolar disorder with a concordance rate between MZ twins of around 70%. It seems therefore that genetics are never the whole story. Other factors are needed to trigger the disorder. For example, that high concordance could well be caused by factors in the shared environment. Two identical twins being brought up together in the same house, same school, same friendship groups – it is quite likely that some of their shared behaviour will be learned or acquired from interactions with others and with each other.

Psychologists therefore compare MZ twins with dizygotic (DZ) twins. DZ twins are no more similar than ordinary siblings in that they share 50% (on average) of their genetic inheritance with each other. Since these are also brought up together, share the same home environment etc., they make an ideal group for comparison.

The assumption: if MZ twins (100% shared genes) have a higher concordance rate for a characteristic than DZ twins (50% average shared genes) then that greater similarity or concordance must be due to their genetics.

Other research that can be used to support genetic influence on behaviour includes:

Adoption studies – comparing a trait or characteristic of the child with their biological parent.
Family studies – comparing parents’ traits with their children’s traits.
Selective breeding – this has been done for centuries, by farmers and other animal breeders, and involves artificially selecting animals for breeding. For example, those with a placid temperament or those that are quick to learn. The animals are bred and it can be observed that some behavioural traits are heritable.

Genotype and phenotype

Genotype: the genes you have for a particular trait. This is part of your genetic make-up, found within the nuclei of your cells, and cannot be observed.
Phenotype: the observable characteristic shown, ie how the genes are expressed as a physical, behavioural or psychological characteristic. This is determined by genotype in interaction with environmental factors.

A genotype is influenced by environmental factors – for example identical adult twins usually look slightly different because one has exercised more or one has dyed their hair – so despite having the same genes (genotype) the observable traits (phenotype) are different.

Another example – you may have the genotype for being very tall, and therefore the potential to become very tall, but if you are malnourished then you will not actually end up being tall.

Understanding how genotypes interact with the environment can be really beneficial – particularly in the case of genetic diseases. For example, there is a disorder called PKU that leads to severe learning difficulties. If you carry the genes for PKU, you are unable to metabolise a common dietary component (an amino acid called phenylalanine). And as you can’t break it down, it builds up in the bloodstream to toxic levels which damage your brain. So a genotype of PKU, with a normal diet, leads to a phenotype of severe learning difficulties. However, all babies in the UK are routinely tested for PKU at birth. You will have had the test yourself soon after being born – it’s a heel prick test to obtain a drop of blood that is tested. If you have the PKU genotype, you would be put on a highly controlled diet to prevent blood toxicity – and you would not develop brain damage or learning difficulties. So a phenotype of PKU, with a restricted diet, leads to a phenotype of no learning difficulties.

Evolutionary theory

Looking into our evolutionary past – life was a struggle, early death was frequent, and many people did not survive or reproduce successfully. Only those with particular physical and behavioural traits were likely to make it.

Many of our physical and behaviour traits are innate (ie genetically determined / inborn). Some traits can be viewed as adaptive (likely to lead to survival) and some as maladaptive (not likely to lead to survival). During the evolution of our species, if you were lucky enough to have adaptive traits, you had a greater chance of surviving and then breeding successfully and passing on your genes.

Natural selection (the process): the baseline idea is that there is genetic variation within any group of individuals. In early humans, there will have been a range or traits and characteristics. Did they all have the physical traits/behaviours to survive to breeding age? Did they all have the physical traits/behaviours to reproduce successfully? No. Only those early humans that had a survival advantage and a reproductive advantage would have successfully reared offspring and pass on their genes (and traits). This means that over many generations, these traits become more common. Those with innate adaptive traits are likely to survive. Those with maladaptive traits are unlikely to survive.

Examples of adaptive behaviours that gave a survival advantage: cooperative behaviours (eg hunting down a woolly mammoth together), social cohesion behaviours (eg care for the tribe and the tribe cares for you), fight or flight behaviours (staying out of danger), aggression behaviours (competing for resources, making sure you survive). Consider also the common fear responses, such as fear of snakes, which would have aided survival. And of course attachment is an adaptive behaviour, that means babies and young children are kept safe and therefore are more likely to survive. John Bowlby in the attachment unit of the course is a firm supporter of this, with his monotropic theory of attachment.

Examples of adaptive behaviours that gave a reproductive advantage: attraction behaviours, courtship behaviours, parental investment (caring for offspring).

To summarise, if an innate behaviour helped you survive OR reproduce → it got passed on. Which means that adaptive behaviours became prevalent in early human populations and, because they are genetic, are still with us today.

An interesting question: are all those behaviours that were adaptive in prehistoric times still useful?

Biological structures – the brain

Localisation of function: This is the theory that various functions such as memory, language, perception, focused attention etc. are situated in specific brain areas.

The brain can be subdivided into many different areas and structures. Different brain areas are responsible for different types of thinking and behaviour. For example, biopsychologists believe that language in humans is governed by two areas of the cerebral cortex: Broca’s area, which controls the production of speech and Wernicke’s area, which controls the comprehension of speech.

The key localised areas that you need to know are:

Frontal lobe (decision-making, personality)
Parietal lobe (sensory processing)
Occipital lobe (vision)
Temporal lobe (hearing + memory)

There are some key studies to connect to certain localised areas of the brain. For example, Phineas Gage was a railway worker who survived a serious accident in 1848 in which an iron rod passed through his skull, damaging his frontal lobes. Although he physically recovered, his personality changed significantly—shifting from a responsible and polite man to someone who was impulsive, aggressive, and socially inappropriate. This case provides important evidence that the frontal lobes are involved in personality, behaviour, and decision-making, supporting the idea that brain function is localised.

In the memory unit of the course, you will come across the case of HM when covering the multi-store model of memory. Henry Molaison (HM) was a patient who underwent brain surgery in 1953 to treat severe epilepsy, during which parts of his temporal lobes, including the hippocampus, were removed. After the operation, HM developed anterograde amnesia, meaning he could not form new long-term memories, although his short-term memory and older memories remained largely intact. This case supports localisation of function because it demonstrates that the hippocampus in the temporal lobe is specifically responsible for the formation of new long-term memories, showing that different areas of the brain have distinct roles.

Brain chemistry – neurochemistry

Neurochemistry refers to chemical processes in the brain. Neurotransmitters are the chemicals which carry signals between neurons at synapses.

Information travels from one end of a neuron to the other as an electrical impulse. However, the information cannot pass to the next neuron electrically as neurons do not physically touch. There is a gap between one neurone and the next, called a synapse. (Which makes sense when you think about it – if there wasn’t a gap, electrical impulses would spread in an uncontrolled way from neuron to neuron, and the brain wouldn’t be able to control which neural pathways were active – you’d short circuit!) When an electrical impulse arrives at the end of one neuron (labelled below as axon terminal), a chemical called a neurotransmitter is released. This diffuses across the gap and binds to the next neuron. This process is known as synaptic transmission.

Each synapse has only one type of neurotransmitter. But there are quite a lot of different neurotransmitters in the brain overall. Two important ones that we learn about are:

Dopamine (excitatory): this is found in neural pathways involved in pleasure, satisfaction and reward.
Serotonin (inhibitory): this is found in neural pathways involved in mood regulation.

A postsynaptic neuron will probably have lots of presynaptic neurons converging on it. Whether the postsynaptic neuron actually generates an impulse – this is where it gets a bit more complicated. The sum of neurotransmitters it has in all its synapses determines whether the neuron is more likely to fire (excitation) or less likely to fire (inhibition).

But, what do I mean by “the sum of neurotransmitters?” There will be several different presynaptic terminals, all with their own different type of neurotransmitter, all trying to send their message to the post synaptic neuron. The neurotransmitter with the greatest amount, at the point of binding to the receptor sites, wins!

Simply put, if, at the point of binding there were 20 dopamine chemicals being received, and only 5 serotonin, the balance is in favour of excitation, and the neuron is likely to fire. If it were the other way around and there were 20 serotonin and 5 dopamine, the balance will go in favour of inhibition and the neuron is less likely to fire.

This is important to know as it helps you to explain how changes in brain chemistry can create changes in behaviour. THIS IS ESSENTIAL FOR YOUR EXAMS!

For example, people with OCD are thought to have low levels of serotonin, a neurotransmitter involved in regulating mood, anxiety, and impulse control. This lack of serotonin could lead to someone with OCD being less likely to control intrusive thoughts and repetitive behaviours. This is because the low levels of serotonin, makes it less likely that the message (stabilise mood – reduce anxiety) is received.

Additional knowledge – but not necessary for exam: dopamine may also play a role, particularly in the reinforcement of compulsive behaviours. When a person performs a compulsion, their anxiety is temporarily reduced, which can activate reward pathways in the brain. This makes it more likely that the behaviour will be repeated.

Evaluation of the biological approach

Scientific and objective: The medical model is highly scientific. Its use of laboratories and tight control of variables allows for cause and effect to be established and for others to check procedures and allow replication. Research is therefore high in internal validity and very reliable. Its use of observable measures such as scans and other physiological techniques means that it is empirical and highly objective. For example, Maguire used MRI scans in order to measure the size of the hippocampus. This was objective as the equipment collects the data, and there is no chance of human error or bias. You can use loads of studies from biopsychology
Research to support: You can use evidence from many topics of the course including the biological explanations of schizophrenia, the biological explanations of OCD, and the biological explanations of criminal behaviour in our forensic module.
Applications: The biological approach has led to many treatments for various psychological conditions. Examples include SSRIs as a treatment for disorders such as depression and OCD. The fact that SSRIs are a successful treatment for many people supports the biological approach.
Deterministic: This approach states that all that you are is determined for you by your genes, brain chemistry and structure. Does this underestimate the level of free will and personal responsibility that we have. This issue can be highlighted clearly within the biological explanations of crime. This is because biological explanations and our justice system do not align.
Empirical data does not always support causation: Correlation vs causation e.g. brain imaging shows relationships, not cause. Yes Maguire showed that black cab drives have increased hippocampal volume – but is this why they became taxi drivers, why they are good at learning maps, why they have good spatial memory.
There is no attempt to explain the sort of person you are in terms of your environment, upbringing, hopes, expectations, feelings etc.
Nomothetic: A strength of the biological approach is that it is nomothetic, aiming to establish general laws of behaviour. It does this by studying large groups using scientific methods such as brain scans and genetic research, identifying patterns that apply to all humans, such as the role of neurotransmitters like serotonin in depression. This increases the scientific credibility and generalisability of the approach, as findings can be replicated and used to predict behaviour across populations. However, it may overlook individual differences, as not everyone is affected by biological factors in the same way. Therefore, while the nomothetic approach strengthens the biological approach’s scientific status, it can lead to an oversimplified understanding of behaviour.
Reductionist: It explains behaviour in terms of simple biological processes. For example, it reduces complex behaviours such as depression or aggression to factors like genetics, brain structure, or neurotransmitter levels (e.g. low serotonin), ignoring other influences like cognitive thoughts or environmental experiences. This oversimplifies human behaviour, as it fails to account for the interaction of multiple factors. As a result, explanations may lack completeness, and limits the biological approach’s ability to provide a fully holistic explanation of behaviour.

Cognitive neuroscience

Cognitive neuroscience is the scientific study of how brain structures and processes underpin cognition (thinking, memory, language, perception, decision-making). It combines cognitive psychology (study of mental processes) and neuroscience (study brain structure and function). The key assumption and idea of CN is that all cognition is supported by brain activity.

As outlined in localisation of the brain, certain areas of the brain have certain roles e.g. the frontal lobe is responsible for decision making and personality. In order to measure and understand the impact of neurochemistry and brain structures, cognitive neuroscientists use highly objective measures such as brain scans.

Although the ways of measuring the brain is a topic within biopsychology, it is important for you to understand how these form the main basis of cognitive neuroscience. Click on this link to find information about the ways of measuring the brain: https://mrsharrispsychology.school.blog/ways-of-measuring-the-brain/

Evaluation of cognitive neuroscience

One strength of cognitive neuroscience is that it has important real-world applications. By identifying the neural basis of mental processes, it has improved our understanding of psychological disorders and led to the development of effective treatments. For example, research using fMRI has shown reduced activity in the prefrontal cortex in individuals with depression. This has contributed to the development of treatments such as deep brain stimulation (DBS), which uses electrical impulses to regulate activity in specific brain regions and has been shown to alleviate symptoms in patients who are resistant to drug therapies. Additionally, neuroimaging studies, such as those by Braver et al., have identified the brain areas involved in working memory, allowing for the development of targeted rehabilitation strategies that utilise neuroplasticity to support recovery following brain injury. Therefore, the ability of cognitive neuroscience to translate research into practical interventions highlights its value and usefulness.
A further strength of cognitive neuroscience is that it employs scientific, objective methods, which enhances the credibility of its findings. Techniques such as EEG and fMRI provide quantitative data on brain activity, allowing researchers to measure cognitive processes in a precise and replicable way. For example, neuroimaging studies have consistently identified specific brain regions involved in language processing, such as Broca’s and Wernicke’s areas, providing strong empirical support for localisation of function. This represents an improvement on traditional cognitive approaches, which often rely on indirect inferences about mental processes from behaviour and may therefore be more vulnerable to researcher bias.
However, a key limitation is that these methods are often correlational. Although brain scans can identify areas that are active during particular tasks, they cannot establish whether this activity causes the behaviour or is simply associated with it. This weakens the explanatory power of the approach, as conclusions about cause and effect remain uncertain. Therefore, while cognitive neuroscience is highly scientific, its reliance on correlational data limits its ability to provide fully causal explanations of behaviour.
Another limitation of cognitive neuroscience is that it is often reductionist, as it explains complex behaviours solely in terms of brain activity and neural processes. This can oversimplify human behaviour by ignoring other important factors, such as environmental influences, emotions, and social context. For example, explaining depression purely in terms of neurotransmitter levels does not account for life experiences or cognitive patterns, which are also known to play a significant role. This means that while biological explanations may be useful, they may lack completeness and fail to provide a fully holistic understanding of behaviour.