Research Methods - Biological Pyschology Flashcards
What is correlation
A method used to assess the degree to which to co variables are related to
Pros of correlation
- correlational analysis allows us to look at the relationship between continuous variables and determine whether the relationship is significant
- it is a useful way to conduct an initial analysis on data, as if correlation is not strong then we can rule out a causal relationship and if the correlation is strong then further investigation is justified because there may be a causal link
Cons of correlation
- cannot prove causation as it does not show a cause and effect relationship as there has been no IV that has been deliberately altered
- it does not tell us the direction of the effect of the correlation
- there may be intervening variables that can explain why the covariables are linked
- the method used to measure either co variable may lack reliability or validity
What is a scatter diagram
A graph that shows the correlation between two co variables by plotting dots to represent each pair of scores
What is the correlation coefficient
A number between +1 to -1 which describes the correlation in a scatter graph
+1 is a perfect positive correlation
-1 is a perfect negative correlation
What inferential tests
Tests that enable us to study the relationship between two sets of data
Example of inferential test
Spearman’s rho
What does spearman’s rho test for
The relationship between co variables
Steps of spearman’s rho
Step 1:
State the hypothesis
Step 2:
Places scores A and B in a table from low to high
Rank the scores separately for A and B where 1 is the lowest score, if there are two scores that are the same add the ranks consecutive ranks of that score and divide it by 2
Calculate the difference (d) between rank a and b
Square each difference (d^2)
Add up all the squared differences (d^2)
Step 3: find the observed calculated value of rho
rho = 1- 6 x sum of d^2/ number of participants ( number of participants ^2 -100)
Step 5: find critical value of rho
Need to know:
- level of significance: 5% (0.05)
- n value (number of participants)
- kind of hypothesis
Step 6: state the conclusion
Levels of measurement
- nominal data
- ordinal data
- interval data
What is nominal data
- data in separate categories i
Types of brain scans
- CAT scans
- PET scans
- fMRI scans
What are CAT scans
Computerised tomography (CAT Scans) type of brain scans that use X rays and a computer to create detailed structural images of the inside of the body.
Three types of data
- nominal
- ordinal
- interval
Characteristics of nominal data
- data that is put in categories
- only gives little information as it only tells how many people are in each group
Characteristics of ordinal data
- it is data that put in order
- units of measurement are not equal
- does no tell us the difference between the 1st and 2nd and 4th and 5th
- tend to be subjective
Characteristics of interval data
- most complex measurement
- where data is measured using units of equal intervals
What happens in CAT scans
The person lies in a large scanner and the scanner rotates around them, this takes images of the cross section of the brain at different angles
Pros of CAT scan
- they are useful for revealing abnormal structures in the brain
- high quality
Cons of CAT scans
- scans require more radiation that X rays as they more detailed, so the patient is exposed to more radiation so it cannot be used often
- only provide structural information unlike other scans, they do not give information about the activity of the brain, so have limited use in research linking brain areas to particular behaviours
What are PET scans
Positron emission tomography (PET) scans are scans that measure the metabolic activity in the brain
How do PET scans work
A person is injected with a radiotracer, the brain that is the most active will use more of the radiotracer and therefore be detected by the scanner. This info is sent to a computer and the most active areas are red or yellow and the least active are blue
Pros of PET scans
- shows the brain in action which is useful in psychological research
- indicate the specific areas of the brain that are involved in an experience so can provide evidence of the function of the brain
Cons of PET scans
- not easy to interpret, which makes it difficult to draw conclusions about which area of the brain are linked to which behaviours
- ethical issue with the injections of radioactive substances, as it can cause damage to the tissues in the body, they may kill cells or cause mutations in the DNA, this means that the technique cannot be carried out often, limiting the use of PET scans for psychological research