Assumptions of the Biological Approach

What are the key assumptions of the biological approach?

• Everything psychological is at first biological

• To understand human behaviour, we must study biological structures, processes and functions

• All thoughts, feelings and behaviour ultimately have a physical (biological) basis

• Human behaviour is strongly influenced by our genetic makeup and genetic inheritance

• The Central Nervous System (CNS) especially the brain is essential for thought and behaviour to take place

• Humans have evolved biologically

• The biological approach usually involves highly scientific and technological approaches to research

What are biological structures, functions and processes?

Any physical part or system in the body.

• Genetics e.g. the role of inherited traits in behaviour

• Neurotransmitters e.g. the role of serotonin in behaviour

• Hormones e.g. the role of testosterone in behaviour

• Brain structures e.g. the role of the hippocampus in behaviour

How does the biological approach assume a biological basis for behaviour?

It assumes (e.g.):

• Memory is a function of the hippocampus

• Depression is the result of irregular neurotransmission

• Aggression is a product of excess testosterone

What are twin studies used for?

To investigate a genetic basis for specific traits e.g. schizophrenia, IQ, criminality

• Monozygotic (MZ) twins are compared to dizygotic (DZ) twins

• A twin study begins by looking at one twin proband (a person who serves as the starting point for the genetic study of a family); if this twin has the specific trait/behaviour (e.g., schizophrenia), the researchers then see if their twin sibling also possesses that trait/behaviour - if the characteristic is genetic, it would be expected that 100% of MZ twins would share that characteristic, as they share 100% of their DNA

What are concordance rates?

The rate of agreement - the extent to which twins share the same characteristics.

• A high concordance rate indicates evidence of a causal connection between the twin type and the trait/behaviour

What do biological psychologists expect from concordance rates?

• That if a characteristic (e.g. musical ability, schizophrenia or height) is genetic, concordance rates should be higher in monozygotic (identical) twins than in dizygotic (non-identical twins)

• Since monozygotic twins share 100% of their genes whereas dizygotic twins share around 50%

• Biological siblings also share about 50% of genes but are likely to have more considerable differences in terms of environment (e.g. changes in family circumstances, parenting styles, and life experiences over time)

What did McGuffin et al find a concordance rate of?

46% for major depression with MZ twins; for DZ twins the rate was 20%

• This finding provides evidence that there is a strong genetic basis for depression, yet it cannot be said that depression is fully a genetic trait

What does the biological approach say about inheritance?

Psychological characteristics, such as intelligence, are inherited genetically, in the same way as physical traits like height or eye colour.

Why might monozygotic twins genes be expressed differently, despite having the same basic genes (genotype)?

Due to environmental factors (nurture) or inherited factors (nature).

What is genotype?

A person’s particular set of genes that make up their DNA.

• Everyone has a unique genotype (except from monozygotic twins, who share 100% of their DNA)

• It determines physical characteristics such as eye and natural hair colour

• It is set/fixed at the point of conception i.e. it can’t be changed (unless a specific, spontaneous, very rare, genetic mutation occurs)

What is phenotype?

The way a person’s genotype is physically or behaviourally expressed through physical, behavioural and psychological characteristics e.g.

• Height

• Eye colour

• Hair texture

• Blood type

What can environmental factors do to a person?

Influence a persons phenotype.

• E.g. An individual's genotype will determine how tall they could potentially grow; however, their diet in childhood will determine whether or not they reach their maximum height 

What can a person’s genotype do?

Predispose (make susceptible) them to specific behaviours, e.g. criminality but if specific environmental factors are not in place, then this aspect of their genotype may never be expressed in their phenotype

• If someone with potential criminality in their genotype has a secure home, a good education, a good income and happy relationships, they are unlikely to turn to crime

• If someone with potential criminality lives in adverse social conditions, then they are more likely to turn to crime

What factors can cause monozygotic twins phenotypes to present differently?

• Upbringing

• Friendship groups

• Hobbies

• Careers

,etc.

What theory did Charles Darwin propose to explain the evolution (progressive change) of animals and plants?

The theory of natural selection.

• Any genetically determined behaviour that enhances an individuals survival (and reproduction) will continue in future generations i.e. be naturally selected

Why does natural selection occur?

Because some traits give the possessor advantages, meaning the individual is more likely to survive, reproduce and pass on these traits.

What are some examples of specific human traits which have evolved via the process of natural selection?

Aggression

• Evolutionary usefulness to fight off predators and enemies

Memory

• Evolutionary usefulness to recall the location of food sources

Language

• Evolutionary usefulness to communicate with tribe members

Mate selection

• Evolutionary usefulness to select a mate who will bear healthy offspring

Due to natural selection, behaviours and traits which are useful for survival and reproduction are retained, and those which are not eventually die out.

What are adaptive behaviours?

Those which increase the chances of survival and reproductive success.

• This is why these behaviours are inherited through the generations, i.e., how we behave now is the product of causes rooted in the distant past

  • This is known as the ultimate causes theory of behaviour - that past conditions and stressors have led to the information encoded in human DNA

What is neurochemistry?

The action of chemicals in the nervous systems.

• Much of our thought and behaviour relies on chemical transmission in the brain

• This occurs using neurotransmitters (synaptic transmission)

• An imbalance of neurochemicals in the brain has been implicated as a possible cause of mental health conditions, for example low levels of transmitter serotonin in OCD and overproduction of dopamine in schizophrenia

What is neuroscience?

The study of the nervous system.

What has been developed over the last 50 years to study brain structure and function?

Many new imaging techniques.

• MRI (magnetic resonance imaging) produces data on brain structure

• Functional MRI (fMRI) can follow brain activity and reveal how the brain functions

What is an example of cognitive neuroscience?

Nina Lisofsky et al. (2014).

• The team used fMRI and PET scans to locate a network of brain regions which are activated when we tell lies, including the prefrontal cortex and the anterior cingulate cortex (ACC)

• Such findings could be applied in criminal trials, to determine whether an accused person is telling the truth, by scanning their brains while they present evidence

What are the strengths of the biological approach?

It has real-world application

• Increased understanding of neurochemical processes in the brain is associated with the use of psychoactive drugs to treat serious mental disorders

• The BA has promoted the treatment of clinical depression using antidepressant drugs that increase the levels of neurotransmitter serotonin at synapses - such drugs have been associated with the reduction of depressive symptoms

• However, they don’t work for everyone, which challenges the biological approach as it suggests that brain chemistry alone may not account for all cases

Use of scientific methods in investigations

• The BA makes use of a range of precise and highly objective methods, these scanning techniques include fMRIs and EEGs, with advance technology, it’s possible to accurately measure psychological and neural processes in ways that are not open to bias - the BA is based on objective and reliable data

What are the limitations of the biological approach?

It offers casual conclusions

• The BA offers explanations for mental illness in terms of the action of neurotransmitters in the brain

• The evidence for this relationship comes from studies that show a particular drug reduces the symptoms of a mental disorder and this is assumed that the neurochemical in the drug causes the disorder (like assuming the cause of a headache is lack of paracetamol, simply because taking paracetamol relieves symptoms of a headache) - discovering an association between two does not mean that one is a cause

The biological approach is determinist

• It sees human behaviour as governed by internal, genetic causes over which we have no control over

• However, a way in which an individuals genotype is expressed (phenotype) is heavily influenced by the environment, not even identical twins who share the same genes look the same and think the same

• Also, a purely genetic argument becomes problematic when we consider things such as crime, could a violent criminal, for instance, really exclude their actions by claiming their behaviour was controlled by a ‘crime gene’ - suggests that the biological view is often too simplistic and ignores the mediating effects of the environment