Edexcel AS Unit 2 Biological approach revision notes

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Report Thread starter 9 years ago
Well for me I always thought that the biological approach had the most in it to learn, so I've started making my revision notes for it today. Thought I'd share what I've done so far and I'll post the whole thing as a downloadable doc when I'm done with it. Hope it helps

Biological Approach notes
Key terms:

Central nervous system
Brain lateralisation

What you must know:

Define and explain the biological approach
Describe and evaluate biological research methods to understand how psychologists study human behaviour
Describe an evaluate biological theories of gender development
Describe and evaluate two research studies from the biological approach
Describe a key issue and explain it using the biological perspective. I have chosen to cover 'Is autism an extreme male brain condition'?

Introduction to the approach

What is the biological approach?

The approach combines both psychology and biology to explain basic differences between males and females, up to complex phenomena such as memory, language and perception. This is the most scientific of the AS approaches.

Heb's book, The Organisation of behaviour is what led to the main development of the biological approach. He conducted research using both animals and humans. Previously the belief was that human behaviour was far to complex to be merely broken down into chemical changes, Heb's theory sparked off debate about where human behaviour comes from and led to research in order to test whether biology determined behaviour.

Advances within the biological approach

The biological approach is more younger than other approaches such as psycho dynamic and the learning approach. This means that while it has achieved a lot in its short time, it still has a long way to go.

Psychologists from the biological approach use brain scans to see the living brain and how it works. As every new type of brain scan is developed, this provides us with a clearer picture which can provide us with more information about the brain. Lesion studies, where parts of the brain are disabled in order to see how it affects behaviour are often used, however new techniques are always being developed to ensure that any damage caused to the brain in animals for research does not have to be permanent. (This is still a fantastic ethical point if it needs to be).

The biological approach has investigated areas such as drugs for mental illness e.g anti psychotic, genetic basis of academic ability (Intelligence) and cause and effect of stress. The research used within this approach have a focus on control, to ensure they are scientific. This leads the research to be done primarily in a laboratory setting, with strict controls over the variables.

There are two focusses of where our behaviour comes from in this approach:
It is the result of genes we possess since contraception
That our behaviour is controlled by activity in the central nervous system, the brain.

Methodology of the approach

Describe and evaluate twin studies and adoption studies as research methods
Describe PET and MRI scanning techniques
Describe and evaluate the use of animals in lab experiments, strengths and weaknesses, validity, reliability, generalisability, credibility, ethical and practical issues.

One of the best ways to find biologically determined behaviour is through identical twin studies, the reason for this is that they share the same genes, however you can also use adopted children who were not brought up by their biological parents. Similarities in behaviour between those with a close genetic relationship can be attributed to that relationship.

Describe and evaluate twin studies and adoption studies as research methods:

So why twin studies?

To see if behaviour is shared by those who are genetically similar. This is investigated by looking at concordance rates (the chance that if one twin has a trait, the other twin will too). E.g. if one twin had schizophrenia, they would check if the other twin had it too. Doing this on a large scale allows the researcher to establish the likelihood that the other twin will develop it too.

A high concordance rate between Monozygotic (MZ twins) would suggest a genetic cause for the trait. By comparing MZ and Dizygotic (DZ) twins we can see if there is a genetic cause as MZ twins share more genes in common, so if there is a higher concordance rate for MZ twins it suggests that genes play a strong part in the behaviour. Twins mostly share the same environment so the similarity in behaviour could be from environmental factors. Psychologists study twins who are reared apart to separate nature and nurture effects on behaviour.

Why adoption studies?

Adopted children share no genes with their adoptive families but share the same environment. Share 50% of genes with each of their biological parents but not the environment. They can separate genetic and environmental influences allowing them to look at similarities with both their biological and adoptive parents. e.g. If a child has high IQ and so does his biological mother, yet his adoptive parents have average IQ, it suggests that it is due to a 'genius' gene.

Evaluation of twin and adoption studies:

+They both are good for testing genetic causes, they try to study those with a close genetic link but not the same environment in order to isolate genetic causes from environmental ones. e..g MZ twins have identical genetic make up, if they are separated all their lives and still show the same behaviour, this suggests that it is down to genes and not environment.
-Twins seperated at birth still share the womb for 9 months, which could cause similarities in behaviour. They also share a pre natal environment with the biological mother, which could influence child development. Mother's health, nutrition and drug taking while pregnant can affect the child's development.

Adoption agencies often try to find similar homes for separated twins, so they may be brought up in similar environments. Traits they share may be the result of similar upbringings and not genes that they share.
Separated twins are minimal, therefore sample sizes are small and generalisation is difficult.
Twin and adoption studies participants are usually gathered using advertisements asking for suitable people to volunteer and take part. This could lead to sample bias as only certain types of people would come forward for the study.

Describe PET and MRI scanning techniques

MRI (Magnetic Resonance Imaging) scans:

Sees a brain inside the skill just like an X ray.
See the structure of the brain, whether damage or tumours are that may need treatment
Patient is placed in a large scanner which passes a strong magnetic field through their head.
Nuclei of some atoms in certain molecules sin in a particular way when they are placed in a magnet, this allows a detailed picture of the brain to be generated on the computer.
Within the scanner, electromagnetic waves are passed through the body by the magnet, the nuclei in hydrogen molecules emit their own radio wave at a frequency that the scanner picks up.
Hydrogen concentrations vary in areas of the brain, therefore a detailed image of the brain at cross sections can be seen.

Positron Emission Tomography (PET) scans:

Allows us to see a picture of a 'working' brain.
Shows any malfunction, allowing us to identify damage or tumours.
Patients are injected with glucose or water labelled with a radioactive tracer while they lie with their head in a scanner.
As the substance reaches the brain, the brain cells take up the oxygen in the water/glucose and the tracer decays.
Once the tracer decays, it emits positrons, the more glucose or oxygen the cells in the brain use up, the more positrons emitted in that area of the brain. As the positrons are emitted, they collide with electrons and form gamma rays which are detected by the scanner to produce an image of the activity in areas of the brain.

Describe and evaluate the use of animals in lab experiments, strengths and weaknesses, validity, reliability, generalisability, credibility, ethical and practical issues.

Issues of validity, reliability and generalisability:

Animals are often used in biological research, primarily with lesion studies. Brain damage can be permanent to animals when trying to shut off parts of their brain temporarily. The damage to the brain would be the independent variable (IV) and the resulting change would then be the dependent variable (DV). By comparing these brain damaged animals with a control group with fully functioning brains, we can see which parts of the brain control which type of behaviour.

Evaluation of lesion studies using animals


Small rats and mice are easier to house and monitor during research than humans
Large samples can be bred in a short time, compared to humans
Harm can be caused to animals that cannot be done to humans, assuming that that the knowledge gained will significantly benefit others
Animals are more likely to be naïve participants. Validity of the experiment will thus be higher, as there will be no demand characteristics or social desirability bias.


Using animals can be more expensive than humans because only the highest level of care is acceptable
Human and animal brains are different. There is no guarantee that the effect shown on an animal brain will be the same as that of a human brain.
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Report 9 years ago
hey do you have these notes for the other topics.. its really good!
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Report 9 years ago
just read your sentence at the top, the full doc would be great!
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Report 5 years ago
Thank u so much . I am so relieved

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