RESEARCH METHODS - BIOLOGICAL Flashcards
(16 cards)
What is correlation?
a method used to assess to which degree two co-variables are related
What are the strengths of correlational research?
Correlational analysis provides a means of looking at relationships between continuous variables and determine whether the correlation is significant or not
It’s a useful way to conduct a preliminary analysis on data (if a correlation is not strong then we can rule out a causal relationship)
Research is more valid and realistic as its less contrived and fewer controls are needed (more ecological validity if looking at things that occur naturally)
What are the weaknesses of correlational research?
Cannot show a cause and affect relationship because there is no IV that has been deliberately manipulated (can be misinterpreted)
If co-variables are correlated one may be causing the changes in the other but we don’t know the direction of this effect
There may be intervening variables that can explain why the co-variables being studied are linked
The method used to measure either co-variable may lack reliability or validity
What are the different types of correlation?
Positive correlation: when one variable rises and so does the other
Negative correlation: when as one variable rises, the other falls
Curvilinear relation: when there is both a positive and negative correlation between two variables
Zero correlation: there is no clear real relationship between two variables
What are tests of correlation?
inferential tests that enable us to study the relationship between two sets of data (looking at the relationship between the variable, not the difference)
What is a correlational hypothesis?
states the relationship between the co-variables, not the difference (eg there is a positive difference between…)
What is a Spearman rho Test, and how is it carried out?
A test of relationship between co-variables, and the data must be ordinal or interval
The process involves:
State the alternative hypothesis
Place raw data in table and perform calculations (rank A and B separately, calculate the difference between the ranks, then square each difference and add all the squared differences)
Find the observed value using the equation (in the booklet)
Compare to the critical value and state the conclusion
What are the three forms of data?
Nominal data: data is in separate categories, such as grouping people in your class according to their height (eg tall, medium and small)
Ordinal data: data is ordered in some way, for example each person in your class lines up in order of size and then data is written in this order
Internal data: data is measured using units of equal intervals, such as measuring everyone’s height in centimetres (level of measurement is more precise)
What is a CAT scan?
using X-rays and a computer to create detailed structural images of the brain from different angles (all the ‘slices’ are put together to create an image of the brain)
What are the strengths and weaknesses of CAT scans?
Strengths:
Useful for revealing abnormal structures in the brain, such as tumours or structural damage
The image provided by the CAT scan is much higher than that of traditional X-rays
Weaknesses:
CAT scans require more radiation than traditional X-rays, and the more detailed and complex the CAT scan is, the more radiation the patient receives
Only provide structural information, and doesn’t give information about the activity of the ‘live’ brain which means they have limited use linking brain areas to behaviours
What are PET scans?
measures metabolic activity in the brain by injecting the patient with a small amount of radioactive substance (eg glucose) which the scanner will detect in the most active parts of the brain
Most active areas are coloured red/yellow and the less active areas are blue
What are the strengths and weaknesses of PET scans?
Strengths:
Show the brain in action, which is useful for psychological research as it can link biological activity to behaviour
Indicate the specific areas of the brain that are involved in experience (eg provide evidence for localisation)
Weaknesses:
Sometimes the results are not easy to interpret which makes it difficult to draw conclusions
The precise location of active areas in relation to brain structure is difficult to pinpoint
There are ethical issues to do with the injection of the radioactive substance as it can cause damage to the tissues of the body (each participant can only have one every 6 months)
What are fMRI scans?
uses radio waves to measure blood oxygen levels in the brain, and those areas of the brain that are the most active use the most oxygen and therefore blood is directed to that area
This activity is picked up by radio signals and these produce images of successive ‘slices’ which are then turned into a 3D picture
What are the strengths and weaknesses of fMRI scans?
Strengths:
They show important information about which areas of the brain are being used at one time
It doesn’t use radiation so it is a very safe method of studying the brain
The images are extremely clear and can show brain activity to the millimetre
Weaknesses:
It is expensive to use
The technique is only effective if the person whose brain is being investigated status perfectly still and this could be a problem for some people, such as children
There is around a 5 second lag between the brain activity and the image appearing on the screen, which can cause problems when trying to interpret the information received
What is a twin study?
a study where twins are compared on a specific trait to see how similar they are
If a behaviour is entirely genetic then we would expect MZ twins to have a 100% concordance rate
What are the strengths and weaknesses of twin studies?
Strengths:
Enables researchers to investigate the influence of genes because it is assumed that both MZ and DZ twins share the same environments
Although twins are unusual, information for twin studies is often taken from twin registries which hold information on thousands of twins and also contain information about many variables, making the sample large and more representative
Weaknesses:
Twin studies may overestimate genetic influence, as MZ twins have more similar environments than same sex DZ twins, therefore the similarity could be due to the environment as well as genes
Twins study provide a broad indication that a behaviour is a genetic origin, but they cannot identify the specific gene involved - therefore it’s a useful starting point for research but more recent technologies are required for us to study specific gene influences
