Experimental Methods

Question 1

What is a Laboratory experiment?

Answer 1

Carried out in a controlled environment, where the researcher manipulates the IV and measures the effect on the DV

Question 2

What are strengths of using a lab experiment?

Answer 2

• Possible to determine cause and effect relationship between IV and DV
• Controlled environment allows great control over extraneous variables - ensure high internal validity
• Replication is easy - check for reliability
• Participants agree to take part, consent less of an issue (deception may prevent informed consent)

Question 3

What are limitations of using a lab experiment?

Answer 3

• Artificial setting of lab means research may lack ecological validity, making it difficult to generalise results to other settings
• Being in a lab means participants are aware they’re being observed, making demand characteristics more likely which may lower the internal validity
• Fact people are being tested on how they perform on a task increases the likelihood of evaluation apprehension - again, effect behaviour and have an effect on the internal validity

Question 4

What is a field experiment?

Answer 4

An experiment that takes place in a natural setting where the experimenter manipulates the IV and measures the DV

Question 5

What are the strengths of using a field experiment?

Answer 5

• Ecological validity is easier to achieve as the setting is not artificial, more likely to generalise to other settings
• Participants are often unaware they’re involved in an experiment and will not respond to demand characteristics
• IV still manipulated by the researcher, so cause and effect can still be established
• Replication is SOMET|MES possible, as long as the environmental circumstances do not change too much, reliability can sometimes be checked (not as easily as in lab)

Question 6

What are limitations of using a field experiment?

Answer 6

• The researcher does not have control of the setting, so there is a greater chance of confounding variables, making it less likely the experiment has internal validity
• Difficult to replicate (precise circumstances may not occur twice) so may be difficult to check the reliability of the findings
• Difficult to carry out using complicated apparatus
• May be more time consuming if researcher has to wait for the right time of day, right number of people, type of people etc
• Participants usually unaware they are taking part in an experiment, consent is difficult to obtain, debrief may be hard to carry out etc, ethical issues.

Question 7

What is a quasi experiment?

Answer 7

An experiment often conducted in controlled conditions where the IV simply exists so there can be no random allocation to the conditions (may be referred to as not a true experiment) - No control condition, simply a comparison condition

Question 8

What are the strengths of using a quasi experiment?

Answer 8

• Enables the investigation of variables that, for either practical or ethical reasons, cannot be manipulated by the researcher

Question 9

What are the disadvantages of using a quasi experiment?

Answer 9

• There is less control over extraneous variables (e.g. participant variables) so there is a greater chance that these will confound the results - validity harder to achieve
• Because the IV is not manipulated by the researcher, cause and effect relationships cannot be concluded

Question 10

What is a natural experiment?

Answer 10

An experiment where the change in the IV already exists naturally, rather than being manipulated by the researcher

Question 11

What are the strengths of using a natural experiment?

Answer 11

• Enables the investigation of variables that for either practical or ethical reasons, cannot be manipulated by the researcher
• Often the ecological validity is high, as the setting is the real world, and it is real events that are being studied

Question 12

What are limitations of use a natural experiment?

Answer 12

• Less control over extraneous variables (e.g. participant variables), so there is a greater chance that they will confound the results, internal validity harder to achieve
• Because the IV is manipulated by the researcher, cause and effect relationships cannot be concluded
• As they rely on naturally occurring events, they are difficult to replicate, so it is hard to check for reliability
• May be ethical issues which need to be controlled

Question 13

What is repeated measures design?

Answer 13

An experimental design where each participant takes part in both/all conditions of the IV

Question 14

What are the strengths of using RM design?

Answer 14

• Participant variables are controlled - helps to increase the internal validity
• Fewer participants are needed - reduces time and expense

Question 15

What are the limitations of using RM design?

Answer 15

• Possibility of order effects - participant may get better through practice OR performance get worse due to fatigue or boredom
• Participants may be able to guess the purpose of the experiment as they’re exposed to both conditions of the IV - performance may change due to demand characteristics
• Inappropriate design if participation in one condition would affect the response in the other condition (deception involved)
• Some experiments its impossible for participants to be in both conditions e.g. sex differences

Question 16

How are order effects controlled?

Answer 16

Counterbalancing - half participants do condition A then B, other half do B, then A, any order effects should cancel each other out

Question 17

What is independent groups design?

Answer 17

An experimental design where each participant only takes part in one condition of the IV

Question 18

What are strengths of using independent groups?

Answer 18

• No problem with order effects
• Only see one value of IV - less problem with demand characteristics
• Enables experiments where completion of the task would make it impossible for participants to complete the task a second time
• Often, both conditions can be tested at the same time, which saves time

Question 19

What are the limitations of using independent groups?

Answer 19

• Participant variables can be a problem as if the participants in each condition differ in some systematic way, this can be a confounding variable
• More participants are required, which can be time consuming

Question 20

How can participant variables be addressed?

Answer 20

By randomly allocating participants to conditions

Question 21

What is matched pairs design?

Answer 21

An experimental design where pairs of participants are matched on important characteristics and one member is allocated to each condition of the IV

Question 22

What are strengths of using matched pairs design?

Answer 22

• Reduced chance of participant variables confounding the results compared to IG design
• Since participants only do task once, less of problem with them guessing the purpose - less chance of demand characteristics
• Enables experiments to take place where completion of the task would make it impossible for participants to complete the task a second time (knowing about deception for example)
• Enables experiments where participants cannot be in both conditions
• Often, both conditions tested at the same time which saves time

Question 23

What are limitations of using matched pairs design?

Answer 23

• Still possibility of confounding participant variables - impossible to have perfect match on many variables
• Matching participants is extremely time consuming, makes the experiment more expensive and difficult to carry out practically

Question 24

What is the independent variable?

Answer 24

The variable that the experimenter manipulates

Question 25

What is the dependent variable?

Answer 25

The variable that is measured to tell you the outcome

Question 26

What is an extraneous variable?

Answer 26

Variables that if not controlled may affect the DV and produce a false impression that an IV has produced changes it hasn’t - NOT SYSTEMATIC

Question 27

What is a confounding variable?

Answer 27

An extraneous variable that varies SYSTEMATICALLY with the IV so we cannot be sure that the true source of the change of the DV

Question 28

What are common examples of extraneous variables?

Answer 28

Age of participants, lighting or noise conditions in a lab

Question 29

What are participant variables?

Answer 29

any aspects of the participants that could affect the research e.g. age, sex, intelligence

Question 30

How do we control for participant variables?

Answer 30

• Use RM design where possible
• Where not possible, use matched pairs
• If independent groups is necessary, use random allocation to conditions

Question 31

What are situational variables?

Answer 31

any aspects of the environment in which the research is taking place that could have an effect e.g. temperature, noise level, visual cues, time of day, light level etc

Question 32

How do we control for situational variables?

Answer 32

ensure all conditions are carried out in the same situation - STANDARDISATION

Question 33

What is participant reactivity?

Answer 33

when individuals alter their performance or behaviour due to the awareness that they are being observed - may be positive or negative, but threatens the internal validity of the experiment

Question 34

What are demand characteristics?

Answer 34

when participants try to work out the purpose of the research, and behave difference as a result - behave according to interpretation of the situation

Question 35

How do we reduce the effect of demand characteristics?

Answer 35

• use independent groups OR matched pairs design
• double-blind procedure
• deception

Question 36

What is a double-blind procedure?

Answer 36

participants and researchers who interact with them are unaware of which condition they have been placed in, reduce knowledge of how they’re expected to behave)

Question 37

What is evaluation apprehension?

Answer 37

participants’ concern about being evaluated/judged in an experiment - suspect that arousal level will increase as they’re concerned others are evaluating their behaviour which may effect the validity of the research

Question 38

What are investigator/experimenter effects?

Answer 38

any aspects of the person conducting the research that can effect the results e.g. personality, looks, sex, educational/racial background, age etc.
Examples:
- experimenter expectancy (can have systematic effect on how experimenter unconsciously communicates - use double-blind)
- loose procedure effect (if procedures not specifically specified leaves room for investigator to influence how it’s conducted, influencing results - control with double-blind and standardisation)
- design effect (not allow time for effect to appear)
- investigator fudging (fudge/fake results)

Question 39

What is standardisation?

Answer 39

ensures all participants have the exact same experience so that differences between experience of individuals does not case the participants to engage with the study differently

Question 40

What is operationalisation?

Answer 40

clearly describing the variables (IV and DV) in terms of how they will be manipulated (IV) or measured (DV)

Question 41

What is an aim?

Answer 41

a precise statement of why a research study is taking place - state what is being studied and what the study is trying to achieve

Question 42

What is a hypothesis?

Answer 42

a precise, testable statement of expected outcome of a research study - variables must be operationalised

Question 43

What are the two types of experimental (or alternative) hypothesis?

Answer 43

Directional or Non-directional

Question 44

What is a null hypothesis?

Answer 44

States what will happen if the theory is wrong - No significant difference/correlation - realise we cannot prove a theory true and only fail to falsify it