RMA: WEEK 4 Flashcards
1
Q
Within-subjects design
A
- AKA repeated measure designs.
- All participants receive all levels of the independent variable. (e.g: all ppts experience different doses of a drug)
2
Q
Between-subjects design
A
- AKA independent groups
- Different groups of participants receive different levels of an independent variable.
- e.g: Experimental and control group when testing the effectiveness of a drug.
3
Q
Advantages of between-subjects design
A
- No order effects.
- Some experiments can only be between-subjects.
- Naïve participants > no learning in between so ppt wont improve significantly in second condition
4
Q
Disadvantages of between subjects design
A
- Lots of participants. > expensive to gather for their time
- Characteristics might differ between groups.
e. g., how well they study generally, with or without music. (individual differences + participant variables) > don’t know if performance is due to IV or individual diff
5
Q
How to counteract problems with between subject design
A
- Participants randomly assigned to groups > random allocation
- Match participants based on characteristics that may impact DV then assign to different conditions (some nuisance v cannot be controlled or some v matched however)
6
Q
Advantages of within-subject design
A
- Fewer participants required. > cheaper
- Reduced individual differences.
e. g., confounding variables from each participant (essay writing ability) > Participants are used as ‘their own controls’. (matched to themselves)
7
Q
Disadvantages of within-subject design
A
- Carryover effects. > Effect of one carries over to next session thus improves performance (e.g., ‘benefits’ from silent study affect following ‘with music’ behaviour.)
- Order effects > could get tired and put in less effort
8
Q
How to counteract problems in within-subject design
A
- order of conditions could be randomised to avoid carryover effects
- conditions could be counterbalanced (A>B then B>A)
9
Q
Counterbalancing
A
Half the participants do the conditions in one order than the other half do the opposite order (eg: 1/2 do A-B, 1/2 do B-A) there will still be order eff, results will just be more representative and general as an average
-Controls for order effects in repeated measures
10
Q
Counterbalancing + latin square design
A
- if there are many conditions, there will be a higher amount of possible orders > inefficient to manually create this many orders so latin square resolves this
11
Q
Latin square design
A
- Doesn’t use all possibilities available but has X amount of rows and columns where each condition occurs an equal amount of times at different points
- Carryover effects are still possible here > counterbalancing + latin square des doesn’t eliminate carryover effects but reduces them
- To find out how many possible combinations there are, you should multiply each condition by each other so if you want to completely counterbalance 5 conditions, you do 5x4x3x2x1=120 > 120 possible orders
12
Q
Quasi-experiment
A
- One (or more) of independent variables are selected.
i. e., not manipulated. > Experiment where the IV is natural and re-occuring (eg age or gender) and impacts the DV - e.g: effect of education on memory skills (whether you have a degree or not cannot be manipulated)
- Participants not randomly assigned to the levels of the independent variable (education). > E.g., whether they have a degree or not.
13
Q
Advantages of quasi-experiment
A
- Examination of variables that would be unethical to manipulate. > e.g: studying kids who have been institutionalised cannot be manipulated (cannot send a child to a care home), it is something which has already happened so it is ethical to study
14
Q
Disadvantages of quasi-experiment
A
- Leads to more confounding variables that cannot be removed. > E.g., people with better memories more likely to go to university?
- No strong conclusions about cause and effect possible. > many other variables could impact the person’s memory (e.g heritability)
15
Q
How to counteract problems with quasi-experiments
A
- Matching participants + correlating
- If treatment study: tests before and after treatment.
(participant are their own control)
16
Q
Types of sampling
A
- Random sample: Everybody has equal chance of being selected usually practically difficult as generators which may use emails e.g don’t truly include everyone like people who don’t have emails > randomly pick from a hat
- Stratified sample: Random selection of each subgroup (e.g gender) of the population> advantage of this is key groups in sample.
- Quota sample: Representative sample that meets quotas/targets. > e.g. 50% females (14% left-handed).
50% males (16% left-handed).
17
Q
Psycho-physiological measurement
A
- Aims to test the effect of psychological variables on physiological processes. (can be experimental OR non experimental)
- E.G: Muscle activity, eye movements or eye blink rate + brain imaging / neurophysiological measures.
- measured using brain imaging to see localisation of activity + timing of brain functions (such as EEG or FMRI)
18
Q
Electroencephalography (EEG)
A
- Electrodes placed on the scalp > detect and measure patterns of electrical activity coming from the brain (event-related potentials > ERPs)
- E.G: Comparing normal and abnormal developing children. (Differences in activity in the brain.)
19
Q
Advantages of EEG
A
- Excellent temporal resolution > no time gap between what is measured + what happens in the brain > instant so we know exactly when certain activity occurs
- Relatively inexpensive
20
Q
Disadvantages of EEG
A
- Poor spatial resolution > looks at areas but cannot specify particular neurons
- EEG artefacts from e.g blinking or eye movements can impact activity traced > think we are measuring something we aren’t
- Surface activity > only measures electrical activity on the surface of the brain
21
Q
Functional Magnetic Resonance Imaging
FMRI
A
- 2-D and 3-D views of the brain
- Measures amount of blood oxygen in brain > is a measure for activity (more blood oxygen in active area)
- E.g: Localization of visual and auditory functions.
22
Q
Advantages of FMRI
A
- Excellent spatial resolution (2-3mm). > can see specific neurons
- Accesses all areas of the brain > unrestricted unlike EEG
23
Q
Disadvantages of FMRI
A
- Poor temporal resolution (5 seconds after a stimulus) > we won’t know what happens at the exact time
- Expensive.
- Claustrophobia inside the scanner + participants must not move > ppt are more likely to be uncomfortable thus less people will be willing to partake in the study
