The Biological ApproachSpecification details:

Basic assumptions of the biological approach including: the influence of genes, biological structures and

neurochemistry on behaviour, genotype and phenotype, genetic basis of behaviour, evolution and behaviour.

Pages 112-113 of course text

book

What is the biological approach?

• The biological approach combines psychology and biology to provide *physiological explanations for human behaviour.

• Biological psychology tries to explain how we think, feel and behave in terms of physical factors within the body.

*Physiology: the study of the body and its parts and how they function

Basic assumptions

• Everything psychological is at first biological• The approach investigates how biological structures and

processes within the body impacts on behaviour.• Much of human behaviour has a physiological cause which

may be genetically or environmentally altered.• Genes affect behaviour and influence individual

psychological differences between people. Evolutionary psychology considers genetic influences in common behaviours

• Psychologists should study the brain, nervous system and other biological systems, e.g. hormones, chemicals acting on the brain

• 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)

Psychologists are interested in trying to determine and provide evidence for the extent to which

behaviours, or a characteristic such as intelligence, are the product of inheritance (genes), or

environmental influences

Genetic basis of behaviour

Methods of investigating the genetic basis of behaviour There are different methods for investigating the extent to which psychological characteristics are affected by inheritance from parents and evolution genetic basis of behaviour:

twin studiesfamily studiesadoption studiesselective breeding

Psychologists are interested in studying twins in order to investigate the genetic basis of behaviour

Zygote A fertilised egg

Twin studies

Monozygotic (MZ)One zygote – these twins are formed when a fertilised cell splits into two and forms two separate embryos

Dizygotic (DZ)Two zygotes – these twins are formed when two separate eggs both become fertilised by different sperm cells

Twin studies

Concordance rates: agreement between

This refers to the extent to which a pair of twins share similar traits or characteristics

i.e. there should be 100% concordance rates between MZ twins if a particular characteristic /trait is a genetic oneDZ twins will show lower concordance ratesComparisons can be made between twins raised together and twins raised apart

Family studies

• 1869 - Francis Galton ‘…all natural abilities are inherited’

• This is a simplistic viewpoint – Galton later had to agree that any resemblance between family relatives could be a result of both genes and shared environment

• However, with alcoholism for example, there is a suggestion of a biological predisposition to the addiction

Adoption studies

These studies involve comparing a trait or characteristic between adopted children and their

biological or adoptive parents.

Selective breeding

• This method involves artificially selecting male and female animals for a particular trait.

• These animals are then put together in order to breed and produce offspring.

• Selective breeding has been used to demonstrate how a number of behavioural characteristics may have a genetic basis. e.g. ‘maze bright’ rats

Genetic basis of behaviour

• There is evidence from twin, family and adoption studies to suggest that certain behaviours, for example, intelligence, are genetically determined

• Research has shown that the environment can play more of a role in determining behaviour than genetics

• Selective breeding studies have demonstrated how a number of behavioural characteristics, for example aggression, can have a genetic basis

Genotype and phenotype

• The basic units of heredity are called genes• Genes function in pairs and the recombination of

genes from parents to offspring provides the basis for genetic variability

• Genes only determine the potential for characteristics (genotype)

• The observable characteristics of an individual (phenotype) depend on the interaction of genetic and environmental factors.

What is a Genotype?

•The actual set of genes an individual has, or is made up of, is a genotype.

•The genetic material is made up of DNA, for sexually reproducing organisms, which are given by the sperm and egg of the parents.

What is a Phenotype?

• An individual's anatomical features or observed traits, such as behavioural and physical characteristics (shape, metabolic activities, size, and colour, etc.), fall under an individual's phenotype.

• These behavioural characteristics and physical attributes are what determines an individual's ability to reproduce and survive in the environment.

The Difference between Genotypes and Phenotypes•The genotype is the genetic programming that provides the phenotype

•To a large extent, an individual's phenotype is determined by its genotype.

•However, genes are only part of the equationGenotype + environment = phenotype

Example

•Hair is a good example. •An individual's genes

determines whether or not they have hair on their head, but how long this hair remains depends on environmental factors, such as excess sunlight, chemicals used on the head, or poor diet.

•This shows that phenotype is influenced by the environment

Twins • Identical twins are another good example of the

interaction between inheritance (genotype) and environment.

• They have the same genetic makeup and they look alike, but they possess different phenotypes.

• Identical twins have differences that allow those who are close to them to tell them apart. Also, their fingerprints are different.

• Twins are genetically the same - any differences you may see between them – for example in personality, tastes and particular aptitudes – are due to differences in their experience or environment.

Recessive and dominant genes

• A gene can be recessive or dominant.• A recessive gene only shows if the individual has

two copies of the recessive gene. For example, the gene for blue eyes is recessive. You need two copies of the gene to have blue eyes.

• A dominant gene always shows, even if the individual only has one copy of the gene. For example, the gene for brown eyes is dominant. You only need one copy of the gene to have brown eyes (and two copies will still give you brown eyes!).

Example

Heterozygous and homozygous genes• heterozygous – the

genotype consists of two different genes, for example Bb

• homozygous - the genotype consists of two genes that are the same, for example BB

Summary

•Genotype is something you cannot see with your eyes (examples: dominant, recessive, heterozygous genes, etc.)

•Phenotype are things that can be seen with your eyes. (example: colours, growth, etc.)

STARTER

Biological Approach

Genes

Biological Structure

Neurochemistry

Genotype

Phenotype

Evolution

Match the key words with the definitions.

Arrangement or organisation of parts to form an organ, system or living thing.

The particular set of genes that a person possesses.

The changes in inherited characteristics in a biological population over successive generations.

Relating to chemicals in the brain that regulate physiological functioning.

The characteristics of an individual determined by both genes and the environment.

A perspective that emphasises the importance of physical processes in the body.

They make up chromosomes and consist of DNA which codes physical features of an organism and psychological

features.

Evolution and behaviour

Evolution: the changes in inherited characteristics in a biological population over successive generations

Charles Darwin emphasised two main concepts in evolutionary theory:•natural selection•sexual selection

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.

• These behaviours need to adapt to the environment that the animal is living in which is dependent on three principles:

the principle of diversity - the variety within a species the principle of interaction - which is how this variety of

species adapt and fit in with the environment e.g. animals that breathe air wouldn’t be able to permanently live under water

the principle of differential amplification - those who adapt to their environment will reproduce and those that do not will die out.

Sexual selection

•Males have an abundance of sperm and can reproduce with as many females as they want.

•Females however, are limited by the amount of eggs she produces and the fact that she has to carry the baby for 9 months and then raise it till the age of 18.

•Females therefore will be more particular about who fathers their children due to the investment they have to make.

Research methods

• The biological approach draws on concepts from the hard sciences and research tends to be highly scientific in nature

• The most common methods include laboratory experiments and observations

• Objective brain recording and scanning techniques are also used

Strengths of biological approach

• It is a scientific approach. This suggests that we can find cause and effect relationships of both physiology and behaviour.

• Scientific approach lends credence to study of psychology – establishes psychology as a respectable science

• Impact of biology on behaviour can lead to treatment and intervention to those suffering

• Understanding how an abnormal brain works can shed light on normal brain functioning

• Measurements can be objective as it can be performed by machines which have no vested interest in the outcome e.g. PET scans, EEGs etc. Use of complex machinery allows accurate and precise measurements

Limitations of biological approach

• It is a deterministic approach as it believes that we are determined by our physiological, genetic or evolutionary make-up. Thus stating that there is no free will.

• This approach is reductionist by stating that all human behaviour can be explained through biological processes and we are therefore not unique as individuals. It is also dehumanising to present humans as ‘biological machines’

• Biological approach ignores the role of the environment etc. it should be used in combination which is known as the biosocial approach.

• Research may focus on rare conditions that have little impact on the everyday lives of most people

• Complex machinery operated by humans and therefore measurements could be subject to human error

• Correlations frequently employed – cannot determine cause and effect• Small or restricted samples make findings difficult to generalise• Laboratory experiments lack ecological validity

Can you?

1. Explain what is meant by genotype and phenotype (2 marks each)

2. Outline the influence of genes on behaviour (3 marks)3. Using an example, explain how neurochemistry can

influence behaviour (3 marks)4. Outline the relationship between evolution and behaviour

(4 marks)5. Outline two weaknesses of the biological approach in

psychology (4 marks)

• Answer the ‘Check it’ questions on page 113

Essay title

Can you answer the question?

Discuss the biological approach in psychology. Refer to at least one other approach in your answer (12 marks)

Homework

Ensure you have written up your class notes to include the following:

•The assumptions of the biological approach•the influence of genes, biological structures and neurochemistry on behaviour, •genotype and phenotype, •genetic basis of behaviour, •evolution and behaviour.•The strengths and weaknesses of the approach