Types Of Experiments + Demand Characteristics Flashcards
1
Q
What are the different experimental designs?
A
- independent groups
- repeated measures
- matched pairs
2
Q
What are independent groups (experimental design)?
A
- Each ppt only takes part in 1 condition, e.g. words or pictures (participant involved in either words or pictures condition - not both!).
3
Q
What are the strengths of independent groups?
A
- Fewer demand characteristics -> ppts may only know their condition.
- No order effects -> only take part in 1 condition, so don’t get bored or have chance to practice/prepare.
4
Q
What are the weaknesses of independent groups?
A
- more ppts are needed.
- Individual differences as the people taking part in each condition are different - one group might simply be better at that task.
5
Q
What are repeated measures (experimental design)?
A
- There is only 1 group of ppts. This group takes part in both conditions.
6
Q
What are the advantages of repeated measures?
A
- No individual differences as the same person does both conditions.
- Can use counterbalancing to make sure the 1st and 2nd condition is not the same for every participant.
7
Q
What is counterbalancing (repeated measures)?
A
- Half of the ppts participate in condition A before condition B and vice versa.
- This means that 1st and 2nd condition is not the same for every participant.
8
Q
What are the weaknesses of repeated measures?
A
- Demand characteristics: ppts know what the experimenters are expecting and may perform to meet that expectation.
- The measure has to be changed, e.g. 2 sets of words to memorise.
- Order effects: boredom, or practise could influence results
- Can be helped by counter-balancing.
9
Q
What is matched pairs (experimental design)?
A
- Type of independent measures design. Matched pairs design involves the use of independent measures, each ppt in group A is paired with 1 in group B.
- Done by finding ppts who can be matched on key characteristics, e.g. IQ, memory ability, gender and so on.
10
Q
What are the advantages of matched pairs design?
A
- No order effects.
- Controls for individual differences. Can be more sure the IV caused difference in DV rather than by big differences between the 2 groups.
11
Q
What are the weaknesses of matched pairs?
A
- Can be difficult to make perfect matches and is costly on money and time.
12
Q
What is a field experiment?
A
- Where the independent variable is manipulated. The effect on the dependent variable is measured.
- They can be in an everyday environment.
13
Q
What are the advantages of a field experiment?
A
- Less artificial than a lab but still an experiment (higher mundane realism) -> represents reality.
- Can be completed in natural environments.
- Avoids ppts effects (if they are not aware of the study) therefore it should produce behaviour which is more natural and valid -> less demand characteristics.
14
Q
What are the weaknesses of the field experiment?
A
- Extraneous variables less easy to control therefore less able to show cause + effect.
- Ethical issues -> ppts unlikely to know they are being studied.
15
Q
What is a laboratory experiment?
A
- An experiment conducted under highly controlled conditions where accurate measurements are possible.
- Decided where experiment will take place, what time, which ppts, in what circumstances and using standardised procedure.
- eliminates of extraneous variables.
16
Q
What are the advantages of a lab experiment?
A
- Controlled environment.
- Minimises problems with extraneous variables.
- Can be easily replicated (repeated) to check same results -> high in reliability.
17
Q
What are the weaknesses of lab experiments?
A
- Artificial environment (low mundane realism).
- ppt may behave differently to normal or be effected by the environment (demand characteristics).
- It therefore may lack generalisability (low external validity).
18
Q
What are demand characteristics?
A
- Any cue from researcher or from the search situation that may be interpreted by the ppts as revealing the purpose of the research outcome.
- ppts may look for cues/clues of how to behave in an experiment.
- Please ‘u’ effect, screw ‘u’ effect.
19
Q
What is meant by the term ‘double blind’ and why is it used?
A
- Neither ppts or the researcher are aware of the aims of the investigations.
- Used in drug trials.
20
Q
What is the term ‘single blind’ and why is it used?
A
- ppts are not aware of the condition they are in.
- Attempts to control for the confounding effects of demand characteristics.
21
Q
What is a natural experiment?
A
- Set in a natural environment. IV not manipulated taking advantage of a naturally occurring event.
22
Q
What are the strengths of a natural experiment?
A
- High ecological validity (represents real life).
- Provides opportunities for research which otherwise may not be available.
- Enables us to study ‘real’ problems.
- Objective research method -> little interference from researcher.
- Few ethical issues.
23
Q
What are the weaknesses of a natural experiment?
A
- A naturally occurring event may happen very rarely which limits the opportunity to investigate this -> also limits generalisability.
- Many extraneous variables which are a threat to ‘cause-effect’ conclusion.
- Ppts not randomly allocated to conditions which may mean that there is some bias in the sample.
24
Q
What is a quasi experiment?
A
- In quasi experiments the IV is a naturally existing characteristic between people and has not been changed by anyone or anything, e.g. gender, eye colour, ethnicity, IQ.
25
Q
What are the strengths of a quasi experiment?
A
- Often carried out under lab conditions so therefore high in controls.
- Enables psychologist to study ‘real’ problems.
26
Q
What are the weaknesses of the quasi experiment?
A
- Like natural experiments ppts cannot be randomly allocated to conditions therefore there may be confounding variables.
- This means that we cannot say cause and effect.
