Types Of Experiments + Demand Characteristics

Question 1

What are the different experimental designs?

Answer 1

• independent groups
• repeated measures
• matched pairs

Question 2

What are independent groups (experimental design)?

Answer 2

• Each ppt only takes part in 1 condition, e.g. words or pictures (participant involved in either words or pictures condition - not both!).

Question 3

What are the strengths of independent groups?

Answer 3

• 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.

Question 4

What are the weaknesses of independent groups?

Answer 4

• 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.

Question 5

What are repeated measures (experimental design)?

Answer 5

• There is only 1 group of ppts. This group takes part in both conditions.

Question 6

What are the advantages of repeated measures?

Answer 6

• 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.

Question 7

What is counterbalancing (repeated measures)?

Answer 7

• 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.

Question 8

What are the weaknesses of repeated measures?

Answer 8

• 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.

Question 9

What is matched pairs (experimental design)?

Answer 9

• 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.

Question 10

What are the advantages of matched pairs design?

Answer 10

• 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.

Question 11

What are the weaknesses of matched pairs?

Answer 11

• Can be difficult to make perfect matches and is costly on money and time.

Question 12

What is a field experiment?

Answer 12

• Where the independent variable is manipulated. The effect on the dependent variable is measured.
• They can be in an everyday environment.

Question 13

What are the advantages of a field experiment?

Answer 13

• 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.

Question 14

What are the weaknesses of the field experiment?

Answer 14

• Extraneous variables less easy to control therefore less able to show cause + effect.
• Ethical issues -> ppts unlikely to know they are being studied.

Question 15

What is a laboratory experiment?

Answer 15

• 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.

Question 16

What are the advantages of a lab experiment?

Answer 16

• Controlled environment.
• Minimises problems with extraneous variables.
• Can be easily replicated (repeated) to check same results -> high in reliability.

Question 17

What are the weaknesses of lab experiments?

Answer 17

• 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).

Question 18

What are demand characteristics?

Answer 18

• 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.

Question 19

What is meant by the term ‘double blind’ and why is it used?

Answer 19

• Neither ppts or the researcher are aware of the aims of the investigations.
• Used in drug trials.

Question 20

What is the term ‘single blind’ and why is it used?

Answer 20

• ppts are not aware of the condition they are in.
• Attempts to control for the confounding effects of demand characteristics.

Question 21

What is a natural experiment?

Answer 21

• Set in a natural environment. IV not manipulated taking advantage of a naturally occurring event.

Question 22

What are the strengths of a natural experiment?

Answer 22

• 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.

Question 23

What are the weaknesses of a natural experiment?

Answer 23

• 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.

Question 24

What is a quasi experiment?

Answer 24

• 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.

Question 25

What are the strengths of a quasi experiment?

Answer 25

• Often carried out under lab conditions so therefore high in controls.
• Enables psychologist to study ‘real’ problems.

Question 26

What are the weaknesses of the quasi experiment?

Answer 26

• 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.