Biological Approach

Biological approach

Main assumptions of the Biological approach:

  • Everything psychological is at first biological.
  • Therefore, to fully understand human behaviour we must look at biological structures and processes within the body (genes, 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)

However, like the psychodynamic and behaviourist approaches, it does assume a hard determinism of behaviour, but is diametrically opposed to the behaviourists, in that it takes the strictly ‘nature’ stance in the nature-nurture debate. In addition, When it comes to treating psychological illness it proposes the medical model, physical interventions such as drugs or surgery. 

Genes

A range of physical human characteristics such as hair and eye colour are determined by our genetics.  Can psychological traits such as intelligence and personality also be caused by what we inherit? Biological psychologists would argue that it does.

Twin 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 extent to which both twins share the same characteristic. For example, research has found that MZ had a 68% concordance rate – this means if one twin had OCD, 68% of the time, the other twin also had OCD. DZ 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 is never the whole story.  Other factors are needed to trigger the characteristic. For example, some of that similarity could well be caused by a 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% 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% 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 include:

  • 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 – involves artificially selecting male and female animals for a particular trait. Then seeing whether their offspring has the same trait.

Genotype and Phenotype

  • Genotype: genetic make-up
  • Phenotype: how the genes are expressed (combined with environmental factors)

A person’s genotype is their actual genetic make up. Genotypes are present within the chromosomes of the individuals and thus cannot be observed.

Phenotype is the way genes are expressed through physical, behavioural and psychological characteristics – they are observable.

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 way identical twins genes are expressed (the phenotype) is different.

The understanding of how genotypes interact with phenotypes can be really beneficial. For example, if a disease or illness is inherited through a genotype, we could potentially utilise phenotypes to try and combat the issues related to the inherited disease e.g. diet, exercise etc.

Evolutionary Theory

Evolution: the changes in inherited characteristics in a biological population over successive generations.
Charles Darwin emphasised two main concepts in evolutionary theory:

  • natural selection: Animals with particular traits that provide them with an advantage are more likely to survive and reproduce thereby passing on their ‘adaptive traits’ to their offspring.
  • sexual selection: females are more choosy when selecting a mate as they have limited eggs

You’ll all be familiar with Charles’ Darwin’s theory of natural selection.  Physical characteristics that make it more likely that an individual of any species will survive to maturity, reproduce and pass on their genes to the next generation will remain in the gene pool.  That characteristic, for example allowing camouflage, greater speed or strength is said to be adaptive However, behaviours and psychological characteristics can also be adaptive.  Examples might include greater intelligence, lower levels of anxiety or greater memory for the location of hidden food caches as in squirrels or nutcrackers.

We would expect characteristics like these to remain in the gene pool.  If this is the case, why do psychological disorders such as schizophrenia, depression and anorexia nervosa have a genetic component?  Why are they being selected for, rather than against?

Buss (1989) found that across all human cultures males prefer younger women (allowing for a longer period of fertility) whereas women prefer older men (usually with more resources).  In evolutionary terms, men make little investment but can continue producing offspring much later into life.  Women on the other hand make a huge physical investment but have a more limited reproductive period.  As a result they are more choosy than men and prefer a man who can pay his way!  Men also prefer a larger hip to waist ratio… a sign of fertility.

Biological/Brain Structure:

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.

Localisation of function: This states that various functions such as memory, language, perception, focused attention etc. are situated in specific brain areas.  So we have come to associate the pre-frontal cortex with attention and concentration, Broca’s area with speech production and the temporal lobes and hippocampus with memory. 

Lateralisation: The concept that right and left hemispheres of the brain are responsible for different skills.  The right side of the brain is arty and sporty, better at spatial awareness, music and facial recognition, whereas the left is the logical and mathematical side and controls our language.

Mass action: Karl Lashely, following his study of rat memory in the early twentieth century, concluded that memories are stored throughout the brain and if one area is damaged, another area can take over its function. This in part led to the bizarre theory, still popularly believed today, that we only use or need 10% of our brains! In fact there are elements of truth in both theories. Generally, the first is most widely accepted and we now know that certain areas do have certain functions, but also that in any given activity, disparate parts of the brain may all work together.  Some have likened it to an orchestra with lots of different sections all contributing to the overall ‘sound.’ 

Brain chemistry – Neurochemistry:

This explanation refers to how chemicals and neurotransmitters influence the nervous system and as consequence, influences behaviour. For example, research suggests that people with OCD have higher levels of dopamine (the feel good neurotransmitter) this is thought to be linked to their need to carry out compulsions, as they get a hit of dopamine every time. Drug research has been used to support the role of neurotransmitters.

Clearly chemicals can drastically affect our behaviour and personality.  We only have to look at the effects of recreational drugs such as alcohol and cocaine to appreciate that. Many of these drugs are chemically very similar to chemicals in the brain, for example morphine is similar to endorphins and LSD is similar to dopamine.  It therefore seems reasonable to assume that varying levels of these brain chemicals could be influential in altering the way we think and behave.  Drug therapies turn this assumption to our advantage.  We know for example that Prozac alters our levels of serotonin and in some people at least, seems to alleviate some of their depressed symptoms.

For your exam, you don’t really expect you to know every single brain chemical and their various effects on our behaviour; however, a few obvious ones are worth considering:

  • Adrenaline: increases our levels of arousal, prepares us for a fast response, particularly in the case of emergency.  Men appear to be more responsive to the effects of adrenaline and this could be due to our early role in hunting and fighting. 
  • Serotonin: has a variety of roles, but generally appears to be the help regulate our mood and also plays a role in getting us to sleep, in appetite and in pain perception.
  • Dopamine: known to be involved in addiction.  It is released when we do anything that produces pleasure. It is also involved in memory, motor movement and seems to play a role in some forms of schizophrenia.

In order to measure and understand the impact of neurochemistry and brain structures, biological psychologist use highly objective measures such as brain scans. We will be covering a range of different brain scanning techniques in the biopsychology section later on in the year. If this interests you, see if you can find the difference between all these scans and what they measure:

  • Electroencephalogram (EEG)
  • FMRI- Functional Magnetic Resonance Imaging
  • PET scan
  • MRI

Evaluation of the Biological Approach

Strengths:

  • Objective: The medical model is highly scientific. Its use of laboratories and tight control of variables allows for cause and effect relationships 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
  • Applications and research to support: It can be claimed with some certainty that there are known biological influences on many behaviours including abnormal conditions, for example, genetic predispositions to certain conditions such as bipolar disorder and schizophrenia. Gottesman (2010) used a national register-based cohort study conducted in Denmark where around 75,000 participants were used. The IV = Parent diagnosed with schizophrenia or bipolar and the DV = Children diagnosed with any mental illness according to the International Classification of Diseases (ICD – 10)  Findings: The risk of being diagnosed with schizophrenia was much greater for offspring of two parents with a diagnosis – 27.3%. The risk increased when the calculation included offspring being diagnosed with other mental health issues – 67.5%. For offspring who had neither parent having any diagnosis, the risk was 1.1%. Similarly brain structures are known to be associated with certain functions, such as Brocas and Wernickes with speech production and understanding.  In recent years the biological approach has increased our understanding of workplace conditions such as stress and through research into circadian rhythms has allowed a better understanding of shift work. 
  • Applications and research to support: The biological approach has produced many treatments for various psychological conditions, which further strengthen their claim of a biological cause of psychological conditions. Examples include benzodiazepines and beta blockers as treatments for stress and anxiety, SSRIs such as Prozac as a treatment for depression and recently deep brain stimulation (DBI), initially for Parkinson’s but now being as a possible treatment for a range of other disorders too. Soomro et al (2009) in a meta-analysis of 17 studies, found SSRI’s to be more effective in reducing symptoms of OCD, than placebo. However, they don’t work for everyone, 30% of patients reported no improvement and in the 70% who did, sometimes the improvements were slight.

Weaknesses:

  • Ignore the interaction between nature and nurture: The biological model does not provide a full explanation of behaviour. As a result there is no consideration of other factors such as thoughts, learning, experience, culture and society, all of which must surely have an impact on whatever it is to be human! It is not possible to separate the effects of nature from nurture, therefore the biological approach ignores a key factor that will play a role in behaviour. At best, the genetic model can only explain predispositions (a tendency or likelihood) to disorders, never the whole picture. For example, the Gottesman study as highlighted above shows that 67.5% of children who have parents with mental health issues will also develop a mental health issue. If mental health was purely genetic, there would be a rate of 100%
  • Deterministic: All that you are is determined for you by your genes, brain chemistry and structure. There is no attempt to explain the sort of person you are in terms of your environment,  upbringing, hopes, expectations, feelings etc.  As a result its treatments are ‘one size fits all.’   Suffering from depression?  Then take one of these twice a day! But these don’t work for everyone! Therefore the biological approach is not considering and free will or individual differences. This is highlighted in the Soomro (2009) study above.