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
What are fMRI scans
- Functional magnetic resonance imaging scans are scans that use radio waves to measure the blood oxygen labels in the brain
How does fMRI scans work
The areas of the brain that are the most active use the most oxygen so more blood is transported to that area, this activity is picked up through radio signals and these signals produce a series of images which are then turned into 3D images by a computer
Pros of fMRI scans
- fMRI scans show which areas of the brain are active
- unlike PET and CAT scans fMRI scans do not use radiation so it is very safe and ethical way of studying the brain
- the images produced by fMRI are clear and show brain activity to the millimetre so is very accurate
Cons of fMRI brain scans
- fMRI are expensive to use
- the technique is only effective if the patient stays perfectly still which may be a problem for some ppl such as children, which limits the use of fMRI scans with some kinds of research
- there is a 5 second time lag bet 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 to a specific trait to see how similar they are to
If behaviour is entirely genetic than MZ twins are expected to show 100% concordance (similarity) and MZ twins to have a higher concordance rate than DZ twins
Pros of twin study
- Enables researchers to investigate the influence of genes as it assumes that both MZ and DZ this share the same environments and that the only difference between the two groups are genetics
- uses data from twin registries which hold data on thousands of twins, showing that the sample is large so data is likely to be representative
Cons of twin studies
- may overestimate genetic influence as MZ twins have more similar environments than same sex DZ twins as they are treated more similarly and tend to share the same friends, this means some of the estimated similarity is actually due to a shared environment
- it cannot identify the genes involved in the similar behaviour so twin studies are useful for starting research but further technology are required to uncover specific genetic influences
What are adoption studies
Studies to discover if genetic factors are implicated if children are more similar to their biological parents with who they share genes with than to their adoptive parents
Pros of adoption studies
- ## It is ethical as adoption studies usually proceed with the presumptive consent of the adoptive parents and the biological parents too, Plus The children’s anonymity is preserved and this respects their privacy and dignity.
Cons of adoption studies
- children may be adopted to families similar to their biological families so environmental influences may be similar, this means that similarities may be due to environmental similarities rather than genes
- people who adopt people’s biological offspring are unrepresentative to the population as they tend to be better educated, have lower rates of mental illness and come from higher socioeconomic groups, this means that any conclusion from adoption studies about the effects of genes on traits may not be representative to the whole population
outline the rational and aim of your study
the rational is 2D:4D digit ratio has been linked to pre-natal exposure to testosterone. Our aim was to see whether there was a correlation between 2D:4D digit ratio (measured in cm) and self reported aggression levels on a scale of 1 - 10
Describe your sample and the sampling method you used for you study
our sample consisted of 13 (male = 1, female = 12) Caucasian participants aged 16 - 17 all who lived in Bristol in the UK and were privately educated at Collegiate School. The sampling method was opportunistic, as we asked the pupils in our psychology class to take part.
what was your hypothesis for the study
There will be a significant correlation between 2D:4D digit ratio (measured in cm) and self reported aggression on a scale out of 10, where 0 = no aggression and 10 = high aggression
what was your null hypothesis for the study you conducted
there will be NO significant correlation between 2D : 4D digit ratio (measure in cm) and self reported aggression on a scale out of 10, whereby 0 = no aggression 10 = high aggression. Any relationship will be due to chance.
what were your operationalised variables
- levels of aggression as measured by a self reported score out of 10, based on the past month, where 10 = high levels of aggression and 0 = no aggression
- 2D:4D digit ratio as calculated by dividing the length (in cm) of the index finger on the right hand by the length of the ring finger of the right hand. A longer index finger will result in a ration higher than 1, while a longer ring finger will result in a ration less than 1.
outline two methodological strengths of your experiment
- we considered ethical implications by informing all of our participants of the full amin of the study, which was investigating the relationship between 2D:4D digit ratio and self reported levels of physical aggression over the past month, therefore ensuring all participants were aware of what they were consenting to take part in, so there was no deception
- we used a reliable method to gain 2D : 4D digit ratio measurements as the instructions were standardised. As all participants were asked to measure the length of their index and ring finger in cm from the crease to the tip, excluding finger nail length before dividing the index finger by the length of their ring finger. Therefore this can be repeated and is reliable
what inferential test did use to analyse your data? Justify your decision
We used Spearmans Rho as the test was for correlation to see if the covariable (2D:4D digit ration) was related to the other (self reported levels of aggression on a scale out of 10). Our data was ordinal level and above as we used ratios, based on measurements of each participants index and ring finger on their right hand in cm and numerical measurements on a rank 1 - 10 where 1= low levels of aggression and 10 = high levels of aggression, the design was a repeated measure as we correlated pairs of data, with measurements of two covariables taken from each participant
Outline two weakness of your practical
- participants only took a single measurement which could have been erroneous but was not checked
-participants were aware of the aim of the study and were measuring their own finger lengths, which could have been subjective so the reliability of the results can be criticised as the data may have not been accurate
describe how you would overcome the weaknesses
- we could have repeated the measurements 3 times and recorded a mean
- we could have used a blind procedure and used 4 disinterested colleagues to measure finger lengths to eliminate bias or subjectivity and to also give inter - rater reliability as any measurements disagreed upon could have been discarded from the experiment
procedure of experiment
1) each participant measure their 2nd and 4th finger on their right hand, from the palmer digit crease to the tip of the finger
2) the measurement of the 2nd finger was then divided by the 4th to obtain a 2D:4D digit ratio
3) They then self reported their aggression over the past month on a scale of 1 - 10 with 1 being the least aggressive and 10 being the most
4) we then used a spearman’s rho statistical test to find out if there was any significant correlation
5) we then verbally debriefed each participant
