Methods Flashcards
Are correlations a method
No, they are a way of analysing a set of data
What type of variables are used in a correlation
Co-variables
THERE IS NO DEPENDENT/INDEPENDENT VARIABLE
What is a co-variable
One of the two variables you measure in a correlation
What is a positive correlation
Both co-variables will change in the same direction
From above zero up to one
What is a negative correlation
Where the co-variables change in different directions
What type of diagram/graph is used to illustrate a correlation
Scatter graph
What are the strengths of a correlation
Useful when unable to manipulate due to ethical reasons
Useful for initial investigation
Rely on quantitative data which is easy to replace increasing reliability
What are the weaknesses of a correlation
- Do not show a causal relationship
- Hidden/Intervening variables could affect the co-variable
- Uses quantitative data so may lack validity
- Issue with direction of causality
What is the lack of direction of causality with a correlation
The two co-variables are linked but the direction is not clear.
You cannot tell which is effecting the other
What is a hidden variable
Where there is no direct link between the two co-variables
However a third variable has an effect on both independently
So as the third variable increases/decreases it causes the co-variables to increase/decrease but the two co-variables do not directly have an effect on each other
What is an intervening variable
Where co-variable 1 has no direct effect on co-variable 2
But does effect variable 3 which in turn has an effect on variable 2
1->3->2
But 1 doesn’t effect 2 directly
What is needed to use a spearmans rho test
Correlation
Ordinal data
Test of association
Different types of brain scans
PET
CAT
fMRI
What does a PET scan show and how does it work
Brain function, red areas = high activity, blue areas = low activity
Pp is injected with radioactive glucose The pp then performs a task As brain works tracer breaks down causing gamma rays to be released Which are detected by a scanner Lots of gamma rays = lots of activity
What does an fMRI scan show and how does it work
Brain function
Pp place their head in a large electromagnet
As neural activity increases there is an increase in blood flow to more active areas, as the brain needs more O2 there
Hb in blood repels magnetic field when it has O2
When it releases O2 it will follow the direction of the magnetic field
Creating a map of activation showing changing levels of neural activity
What does a CAT scan show and how does it work
It shows brain structure
Pass X-rays through the head from different angles
Producing images in slices on the brain
Brain scanning techniques to investigate human behaviour such as aggression
Raine used PET scans with NGRI
Montag used fMRI to investigate the influence of violent video games
Grafman used CT scans to assess the relationship between aggression and frontal lobe lesions
One twin study
Gottesman and shields
MZ = 42%
DZ = 17%
One adoption study
Cadoret and Stewart
Adopted boys increased risk of attention deficit, hyperactivity and aggression as children, if a parent had committed of a crime - nature
Also if a member of the adopted family had psychiatric problems more likely hyperactivity and aggression - nurture
Aggression extremely complex
Could use Tienari
Issues with cause and effect on correlations
Cannot identify a causal relationship
Or the direction of causality
+ PET
Shows brain function and how active each area is
+ fMRI
Non invasive
Practical and safe but not suitable for everyone
Clear images with excellent resolution
Easily repeated
- fMRI
Expensive
Only infer conclusions
Data is correlational not cause and effect
Subjective to interpret the data
Distressing to some individuals as they’re noisy and loud
Not suitable to those with electric implants due to magnetic field
-PET scan
Invasive
-CAT scans
Not suitable for pregnant women as X rays can damage baby
- of twin and adoption studies
Limited sample sizes - bad generalisability
Adoptees tend to be put in families that reflect their family background they came from - so nurture could be similar
Only a correlation doesn’t show causation
+ of twin and adoption studies
Provides evidence for nature vs nurture
Supporting evidence to show clearly different environments have different effects
