Biological Approach

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Defining The Biological Approach

The biological approach combines biology and psychology to explain human behaviour. This approach is founded on two assumptions: that our behaviour is the result of the genes that we posses from contraception; and that our behaviour is controlled by our central nervous system.

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Methodology

Twin studies;

·         This is used to show whether behaviour is shared by those who are genetically identical

·         Psychologists look at concordance rates to determine how likely it is that twins share traits (e.g. the likelihood that if one twin develops schizophrenia  the other one will too)

·         Psychologists carry out tests on a large scale to determine the likelihood (e.g. looking at whether both twins develop the same disorder)

·         A high concordance rate shows that the trait is probably genetic

·         Psychologists try to study twins who have not shared the same upbringing to rule out environmental factors

 

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Methodology

Adoption studies;

·         Studying adopted children to see if behaviour traits can be attributed to genetic factors or environment

·         Adopted children share no common genes with the adopted parents, but they share the same environment. They share 50% of their genes with each of their biological parents, but don’t share the same environment

·         This allows psychologists to separate genetic factors and environmental factors in children who have been adopted at a very young age by looking for similarities between the children and their adoptive parents and similarities between the children and their biological parents

·         If the child has traits that are shared with the biological parents but not with the adoptive parents then this supports the idea that traits can be attributed to genes.

E.g. If a child and biological mother share a common high IQ, but the adoptive parents’ IQ is low then this can be attributed to genetic factors (e.g. a genius gene)

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Evaluating Twin and Adoption Studies

·         Both methods isolate genetic and environmental factors as they study people who share a biological link, but not a common environment

·         Studying MZ (identical) twins is the best way to do this because the two participants share identical genes, but a different environment – so similarities in behaviour due to environmental similarities can be ruled out

·         MZ twins shared the same pre-natal environment so this could cause some similarities in behaviour due to environment

·         Adopted children also shared a pre-natal environment with their mother. This could cause certain traits which are down to environment – e.g. the mother’s health, whether she smokes or drinks etc.

·         Twins separated at birth often share a similar environment as adoption agencies try to find similar families for the twins. So similar traits could be due to similar upbringings

·         Participants  are gathered by volunteer sampling so there may be some bias in the collected data due to the sampling

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Brain Scanning Techniques

MRI (magnetic resonance imaging) Scan;

The patient’s head is placed in a large electromagnet

This causes the nuclei of some atoms to spin in a particular direction – so they produce their own rotating magnetic field which is detected by the scanner.

This means that a detailed image of the brain can be made.

Hydrogen nuclei begin to emit their own electromagnetic radiation (radio waves) as a result of the spin. The more active an area of the brain, the more radio waves (due to their being more H2O present)

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MRI

Advantages;

·         Validity because they produce a real picture of the brain – so what is found by the scan is found in reality

·         Compared to surgery (which is the alternative to a scan), this procedure is non-invasive. This also makes it more ethical; partly because it’s non-invasive and partly because it means animals have to be used less

·         MRI scanning can easily be replicated and repeated, and the same results can be found. This means it is reliable and can be checked for reliability and objectivity.

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MRI

Disadvantages;

 

·         Can be stressful as an injection sometimes has to be administered, and the process is loud and claustrophobic. This sort of stress should not be imposed on participants without careful consideration of ethical guidelines

·         MRI scans produce limited information, for example; they produce clear images of body tissue, but they cannot measure brain activity

 

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PET (positron emission tomography) Scan;

This produces a 3D ‘working model’ of the brain and can be used to show any malfunctions (such as tumours).

The patient is injected with a mixture of water and glucose which incorporates a radioactive isotope that emits β+ radiation. It has a half life of around 109 minutes so it doesn’t stay in the body too long.

The brain cells absorb the glucose which contains the radioactive tracer. The more active an area of the brain, the more it absorbs.

The tracer emits β+ radiation which only travels a short distance (around 1mm) before interacting with an electron causing annihilation of both particles, producing 2 γ (gamma) photons.

This γ radiation is detected by the scanner.

The more active an area of the brain, the more γ is emitted, as more of the tracer is absorbed.

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PET

Advantages;

·         Compared to surgery (which is the alternative to a scan), this procedure is non-invasive. This also makes it more ethical; partly because it’s non-invasive and partly because it means animals have to be used less

·         Validity because it measures what it claims to measure. For example, it’s not easy to check validity with regards to cognitive functions such as speech, but when PET scanning was used, this area of the brain was easily isolated so it was confirmed that a particular area of the brain (Broca’s area) controlled speech

·         Reliable because they can be repeated and they will produce the same results. For example, when someone speaks they use a particular area of the brain every time, so this can be consistently isolated

               

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PET

Disadvantages;

·         Injecting a radioactive tracer into a person is invasive so there are ethical implications that need to be considered, e.g. informed consent.

·         The scan itself can be daunting for some patients due to the enclosed nature of the scanner (may get claustrophobic)

·         Although brain activity shows up clearly on the image, it can be difficult to isolate particular parts of the brain that are used for specific things. For example, to isolate the part of the brain that is used when reading, a patient can read pages of text. However whilst doing this they would almost definitely be using other parts of the brain at the same time

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Animal Experiments

95% are rodents and birds (e.g. mice, rats and pigeons) 5% are primates, cats and dogs

 Studying functions of the brain;

Legion studies (damaging parts of the brain)

Ablation studies (removing parts of the brain)

Testing the effects of antipsychotic drugs on the brain

Research into the effects of physical activity on the brain (e.g. it was found, through animal studies, that more exercise improves the plasticity of the brain)

Studying the effects of sleep deprivation

 

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Animal Experiments

Studying genes;

This is possible because of animals’ short life span and quick breeding.

Gene therapy is used (genes are altered or implanted)

e.g. rats were given drugs to induce a form of Parkinson’s disease and gene therapy was used to see if the symptoms could be alleviated.

Studying the nervous system;

Testing antipsychotic drugs on animals and observing the effects on the nervous system

Investigating changes in neurotransmitters when mice are under stress

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Animal Experiments

Practical advantages;

·         Animals reproduce faster and have a shorter life span than humans so the effects of an experiment can be studied over a life time / generations. This is especially useful in studying genetics

·         Animals don’t show demand characteristics or social desirability as humans do

·         Can cause a level of harm to animals that you can’t with humans

·         Large sample sizes

·         Rats / mice have similar brains to humans

·         Can control all aspects of an animal’s environment, e.g. diet, amount of sleep, exercise...

·         Drugs may need to be administered daily or weekly, so it’s more practical to use animals than humans. Also brain tissue (or other tissue) may need to be examined after the animal’s death, which is also more practical

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Animal Experiments

Practical disadvantages;

·         May be expensive due to the high level of care that’s expected

·         Animals aren’t humans so can the results be generalised? Even though rats have a similar brain structure to humans they’re not identical

·         Studying animals do not take into account the complexity of real life. For example if you change the amount of exercise you do, other areas of your life may change. If an experimenter changes the amount of exercise a rat gets, the rest of their life would remain the same

·         Some things (e.g. Parkinson’s disease) have to be artificially reproduced in an animal which is not the same as a human naturally developing the disease. This reduces validity.

·         Studies may not be credible, for example drug induced diseases are not the same as real diseases and although mice and primates have a similar gene structure to humans they are not identical.

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Animal Experiments

Ethical advantages;

·         Drugs have been developed that otherwise would not have been without the use of animals (such as drugs to treat mental illness or antipsychotic drugs)

·         Some people argue that humans should improve their own quality of life by any means possible (‘pro-speciesism’)

·         These studies are also helpful to the species being studied as we learn more about how we can improve their care

 

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Animal Experiments

Ethical advantages;

·         Drugs have been developed that otherwise would not have been without the use of animals (such as drugs to treat mental illness or antipsychotic drugs)

·         Some people argue that humans should improve their own quality of life by any means possible (‘pro-speciesism’)

·         These studies are also helpful to the species being studied as we learn more about how we can improve their care

 

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Animal Experiments

Ethical disadvantages;

·         Animals are likely to be confined more than they normally would (in the ‘wild’) when they are in a laboratory setting which is unethical because they are either in an unfamiliar environment or  bred specifically for the purpose of being tested on

·         Surgical procedures, which could cause pain to the animal, are used. In some cases they die because of the procedures, or as a result of them have to be put down because of the side effects.

·         Animals are not sufficiently different from humans to be treated as ‘lesser’ species, or as objects. They are still conscious, sentient beings so should be treated as such.

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The Central Nervous System

The central nervous system is made up of the brain and the spinal cord. The biological approach focuses on how the brain specifically controls behaviour.

The brain contains billions of neurons which pass information around inside the brain and around the body; telling different parts of the body what to do.

Neurons communicate with each other through synapses – passing neurotransmitters from the terminal button of one, to the dendrite of the next.

Some synapses are excitatory – encouraging the neuron to fire

Others are inhibitory – telling the neuron not to fire.

Whether or not a neuron fires depends on the amount of excitatory synapses and inhibitory synapses. The neuron will fire if the number of excitatory synapses outweighs the number of inhibitory synapses and vice versa.

 

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Genes in Human Behaviour

A gene is the name given to particular stretches of DNA and RNA.

When DNA is organised in a particular structure it is a chromosome. These are found in the nuclei of cells. The human genome contains 46 chromosomes – 23 are inherited from each parent. This accounts for shared behaviour, personality and appearance traits among family members, as genes are what determine this – to an extent (as well as environmental factors).

This makes up part of the nature vs. nurture debate:

Nature = the idea that our genes and biological make-up determine our behaviour

Nurture = the idea that our environment determines our behaviour

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Genes in Gender

The human genome contains 43 pairs of chromosomes

23 are inherited from each parent.

22 of these pairs make up appearance: eye colour, hair colour, skin colour, height etc.

The remaining pair determines gender – these are either X or Y.

Females have a pair of X chromosomes while males have an X and Y chromosome.

For the first few weeks of pre-natal development every foetus develops the same – in terms of gender. At around 6 weeks of development, the sex organs begin to grow – however, at this point, there is no difference between males and females.

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Genes in Gender

A gene in the Y chromosome contains a gene called SRY. This produces a protein called ‘testis-determining factor’ (TDS). This turns the developing genitals into testicles as opposed to ovaries. So, if there is no Y chromosome then they will continue to develop into ovaries and the rest of the female sex organs. So the default setting for a foetus’ development is female, unless there is a Y chromosome.

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The Role of the Biological Factors in Gender Devel

A gene in the Y chromosome contains a gene called SRY. This produces a protein called ‘testis-determining factor’ (TDS). This turns the developing genitals into testicles as opposed to ovaries. So, if there is no Y chromosome then they will continue to develop into ovaries and the rest of the female sex organs. So the default setting for a foetus’ development is female, unless there is a Y chromosome.

Genetic sex is determined by the chromosomes in the egg and those in the sperm. The egg contains the X chromosome and the sperm contains the X or Y chromosome. If the sperm contains the X chromosome it will be a girl and if it’s the Y chromosome it will be a boy. The Y chromosome will cause the foetus to develop testes. Male speech and comprehension is controlled by the left hemisphere, whilst females tend to be across both hemispheres.

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Evaluation of the biological explanation to gender

·         In the case of David Reimer, the role of genetics overcame the role of the environment in the formation of gender.

·         Koopman et al attached the SRY gene to female embryos and they turned into males.

·         Using animals for studying biological explanations to gender is useful as they breed quickly.

·         The results of biological explanations are based on tests that can be repeated e.g. injecting rats with testosterone or using MRI scans in humans to detect blood flow. The results are replicable and be shown to be reliable.

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Continued

· Humans and animals are different so can’t generalise.

· Pseudo-hermaphrodites such as Daphne Went suggested that the Y chromosome does not necessarily lead to the development of a male. Something else must have an important part to play in gender development.

· Biological aspects are difficult to study without reference to the environment.

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Dr Money Evaluation

Reliability

We can question the reliability of the experiment because it has been suggested that Dr Money used Bruce to support his theory of gender neutrality, so his results may be one sided.

Objective/Subjective

The experiment was objective as there could be a clear comparison between the two brothers about if nurture was more important than nature because they both grew up in the same environment.

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Evaluation Continued

Validity

This was a real-life case that was reported by Money so it has high ecological validity because the boy’s life and the events that happened to him were all real and not manipulated in any way. This means that the conclusions drawn about the importance of biology on gender identity are based on a real experience and not the result of an experimental condition. Furthermore the case study collected many in-depth and valid data.

Ethics

Numerous ethical issues surround this case study. The twins were allegedly encouraged to pose naked in sexual positions which they said was degrading Being involved in the case study was alleged to have been a factor in the mental breakdown of Brian Reimer, and the later suicide of David

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Raine et Al Evaluation

Strengths

·  The main methodological strength of this study is the amount of control the researchers had over the procedure.   For example they used a control group who were matched on variables such as age and sex and they were screened for their physical and mental health.

·   It can also be argued that PET scans are useful because we no longer have to wait for a person to die before we can examine their brain.   The scan allows for a wide range of non-intrusive studies.

·  There is also supporting evidence for Raine’s study.   For example another study by Raine et al. (2000) found that people with anti-social personality disorder had a smaller pre-frontal cortex than normal controls, which supports the findings of this study because it suggests that brain differences may cause anti-social behaviour.  Similarly, in a 20 year longitudinal study Raine measured the way that 3 year old children learned fear.  He found that some showed little or no fear response despite repeated exposure to an unpleasant noise.  These children when looked at 20 years later were significantly more likely to have a criminal record.  This suggests that the emotional connection between experience and fear was missing leading to those affected being more likely to take stupid risks.

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Evaluation continued

Weaknesses

· However the study does have methodological weaknesses.   For example PET scans are still being developed and therefore the data should be treated with caution.

·  The task used by the participants before the scan is a general activity task and has no bearing on violent acts or even the decision to be violent.   Therefore the validity of the task could be questioned.

· The major methodological weakness is related to the design of the study.   It has already been noted that the design was a type of natural experiment, which means that the researchers could not randomly allocate participants to either of the two conditions.  Therefore we have to be careful in making cause and effect statements.  It is possible that any differences in brain activity between the two groups could have been caused by other factors.   We can only say that the study shows a correlation and not a causal relationship.   For example, it could be that the differences between the two groups might have been a result of the crime and its consequences rather than a cause of it.

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Evaluation Continued

· However other evidence suggests that we have to be careful accepting the findings of Raine’s 1997 study.  In a large scale study in Denmark, Raine examined the birth records of people and found 4000 that had suffered complications and therefore possibly brain damage.  He also looked at the records of those who had been rejected by their mothers in the first year of life.  He found that neither factor alone was enough to predict criminal behaviour but for those who suffered both traumas they had more than double the risk of becoming criminals at aged 18.  This suggests that it is nature plus nurture that is responsible for criminal behaviour.

· Raine thinks that the nature of the criminal’s brain should be taken into account in sentencing decisions.  He has acted as an expert witness on behalf of someone with a dysfunctional prefrontal cortex which led to a reduction in sentence from death to life in prison.  If we know that murder may be caused by faults in peoples’ biological make-up, then it means that we can work on ways to treat violent offenders by altering their biology.  There have been some people who have suggested treating criminals by trying to change or alter their brain chemistry.

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Evaluation Continued

· However other evidence suggests that we have to be careful accepting the findings of Raine’s 1997 study.  In a large scale study in Denmark, Raine examined the birth records of people and found 4000 that had suffered complications and therefore possibly brain damage.  He also looked at the records of those who had been rejected by their mothers in the first year of life.  He found that neither factor alone was enough to predict criminal behaviour but for those who suffered both traumas they had more than double the risk of becoming criminals at aged 18.  This suggests that it is nature plus nurture that is responsible for criminal behaviour.

· Raine thinks that the nature of the criminal’s brain should be taken into account in sentencing decisions.  He has acted as an expert witness on behalf of someone with a dysfunctional prefrontal cortex which led to a reduction in sentence from death to life in prison.  If we know that murder may be caused by faults in peoples’ biological make-up, then it means that we can work on ways to treat violent offenders by altering their biology.  There have been some people who have suggested treating criminals by trying to change or alter their brain chemistry.

 

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Key Issue

Is Autism an extreme form of the male brain

 

  • Autism is a developmental disorder which affects a child's ability to interact and build relationships with others, including parents.
  • It is not usually diagnosed until the age of 3 or 4 years but autism is thought to be present from birth and many parents of autistic children report noticing problems well before an official diagnosis is made.

Symptoms of autism can include:

Often, lower than normal language abilities

Low levels of imaginative thinking

Problems with communicating and building social relationships

A preference for order and organisation

A resistance to change

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Autism Continued

  • 3/4 autistic people are male
  • Baron-Cohen et Al (2005) suggested that the brain structure of autistic people is an 'exaggeration' of normal male brain structure. They argue that there are many similarities between he brain of an autistic person and the male brain, and that in the autistic person the brain structure is a more extreme version of the male brain.

Male brain structue is different from female brain structure

  • Male brain is heavier than a female brain. In autistic people, the brain is even heavier than a normal brain.
  • Male brains grow more quickly than females during early development. In people with autism this early growth is even more rapid.

Male brain function is different from female brain function

  • Males are stronger at spatial tasks than females, and tests with autistic people show that they seem to be even better at spatial tasks than normal males.
  • Males develop language slower than females, people with autism are very slow at developing languages.
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Autism continued 2

Male hormones affect development

  • There are 3 times more males than females with autism
  • Males have more exposure to male hormones than females do, as the male hormones are produced by the testes. However, a low level of male hormones is produced by the adrenal glands in females so there is still some possibility of male brain structures in females. This would therefore account for some females developing Autism.

Autism may be genetic

  • Research using twins has found a strong concordance rate of 60-90% for Autism in monozygotic twins, but only 5% in dizygotic twins.

Autism may be the result of other biological causes

  • There is also some evidence to suggest that Autism could be the result of damage caused by undiagnosed phenylketonuria (PKU) in some cases. A build-up of phenylalanine in the body prevents normal brain development so if PKU is undiagnosed it could result in abnormal brain development.
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