Biological Methods

Question 1

Structural scans + S&W

Answer 1

(CAT scans)

• uses X rays to focus on specific area to creat a 2D image of slices of the brain.
• it is useful for detecting areas of brain damage.

S=
Gives accurate detail about brain structure
Quick and non invasive

W=
Only gives the idea of structure not functions of the brain
Use of X rays means some people may be limited due to the use of radiation

Question 2

Functional scans + S&W

Answer 2

PET scans & fMRI scans

PET scans
- use a small amount of radioactive tracer chemical (FDG) which is injected into them.
- given tasks to do that enough brain activity breaking down the Glucose and radioactive atoms (which release gamma rays that are picked up by scanner)
- high conc of gamma rays indicates high brain activity and viasa versa
- A colour image of the brain is produced, with red/ orange indicating higher activity and blue/ green meaning lower activity
- used to investigate the functioning of the brain
E.g. Raine

Brain scans are a strength in Raine as they allow for objective comparison between NGROF and matched pair control group.

S=
Objective comparison can be drawn between brains

W=
Limited use due to the tracer veing broken down so activity has to be short.
Unclear if the radiation even if broken down will have long term consequences.

fMRI scans

• uses a magnetic field
• increased blood flow in areas of brain indecate increased activity as area requires more oxygen and so receives more oxygenated blood (scanner picks up on these changes)
• produces a map of activation of the brain and the different areas.

S=
The detection of blood flow is very precise and has a high degree of sensitivity and accuracy
No danger form radiation

W=
Not as effective at looking at patients with brain damage as that could effect the blood flow.
It only measures activity at rest not functioning so only base line activity could be established.

Question 3

Twin studies +S&W

Answer 3

Psychologists use to test the influence of nature and nurture on human behaviour.

Monozygotic (100% genetic material)
Dizygotic (50% genetic material)

Twin studies compare behaviour between:

• groups of identical twins to see how similar they are to one another
• non identical twins to see how similar they are to one another

The level of similarity is the concordance rate,
If MZ twins have high concordance rate this shows the influence of nature (genes)
If DZ has an equal or higher concordance than MZ twins we can conclude there is no significant genetic component to behaviour.

S=
Produces quantitive objective comparisons.
W=
Twins share genes and environment so it will be hard to untangle nature from nurture
MZ twins may be treated more similarly (clothes ect) so MZ twins may produce higher concordance rate because of this not there genes

Question 4

How are twin studies useful in research

Answer 4

Gottesman and Shields

Looked at the genetic contribution to Schizophrenia.
57 pairs of twins (24MZ + 33DZ)
MZ twins 42% co twin was also diagnosed
DZ twins 9% co twin also diagnosed

High concordance rate suggests that there is a genetic element of Schizophrenia.

Weakness in Gottesman as it can’t be generalised to anyone not a twin so conclusion can not be generalised

Question 5

Adoption studies + S&W

Answer 5

Groups of adoptees are studied and there behaviour is correlated with there adopted families (only environmental factors) and biological factors (small to no environmental factors so any correlation is due to genetic factors).

S=
Good way of objectively measuring the impact of nature and nurture on behaviour. As it separated genes from the environment
Developmental trends can be looked at as the study can be longitudinal in nature

W=
It is still imposible to separate nature from nurture and they have spent some time with bio family before study
The sample size is also limited so generalisability is an issue.

Question 6

Adoption studies usefulness in research

Answer 6

Hetson

Looked at the genetic contribution of Schizophrenia.
47 participants who’s bio mum had SZ and had been put up for adoption compared and had no further contact compared with 50 matched control.
5 participants in experimental group were diagnosed with SZ compared with 0 in control group.
11 in experimental group has spent one year or more in psychiatric ward compared to 2 in control group.
Support the influence of genes in SZ.

W=
As the study had a small sample so can not be generalised

Question 7

Correlations +S&W

Answer 7

Measuring two different variables (Co variables) in order to see if there is a correlation.

Non experimental research method

Co- variables can be directly measured with both primary and secondary data.

The scores of the two variables are plotted on a graph (scatter graph) and line of best fit is drawn.

Positive correlation line goes up
Negative correlation line goes down
No correlation (A line of best fit can't be drawn) 

S=
-Useful as as exploratory method (initial starting point of investigation)
If they do correlate it’s worth doing the study
-Produces quantitive data which is objective and the inferential statistics test (spearman’s rho) can be used to determine if the results are significant.

W=

• Can’t establish causality only coronation as it’s impossible to know which is the causal variable or another variable could be effecting both
• Issue with the validity of measure as the variables that measure in using the offer to determine the variables are valid.

Question 8

Correlations usefulness in research

Answer 8

Dabbs
89 male prisoners who were convicted for a violent or non violent crime.
Measured the amount of testosterone in their salvia of each prisoner.

Those who had committed the violent crimes had higher levels of testosterone compared to the makes with non violent crimes.
Possitive correlation between levels of testosterone and aggression.

S=
Scientific and objective way of measuring testosterone so measure has validity.

W=
Cause and effect can’t be established only correlation between the testosterone levels and aggression.

Question 8

Correlations usefulness in research

Answer 8

Dabbs
89 male prisoners who were convicted for a violent or non violent crime.
Measured the amount of testosterone in their salvia of each prisoner.

Those who had committed the violent crimes had higher levels of testosterone compared to the makes with non violent crimes.
Possitive correlation between levels of testosterone and aggression.

S=
Scientific and objective way of measuring testosterone so measure has validity.

W=
Cause and effect can’t be established only correlation between the testosterone levels and aggression.