Experimental Design

Question 1

what is the experimental approach?

Answer 1

The researcher manipulates one or more variables and controls and measures any change in other variables.

Question 2

what are the variables in experimental research?

Answer 2

independent variabel (IV)
dependent variable (DV)
extraneous variable (EV)

Question 3

what is the independent variable?

Answer 3

The variable that is manipulated

Question 4

what is the dependent variable?

Answer 4

The variable that is measured

Question 5

what is the extraneous variable?

Answer 5

A variable that might have an influence on the DV but is not in the focus of interest

Question 6

what is a confound?

Answer 6

A confound is any uncontrolled extraneous variable that co-varies with the independent variable and could provide an alternative explanation of the results

Question 7

what are the types of independent variables?

Answer 7

situational variables
task variables
instructional variables

Question 8

what are situational variables?

Answer 8

Features in the environment that participants may encounter (e.g. number of bystanders in an experiment on helping)

Question 9

what are task variables?

Answer 9

Vary the type of tasks performed by participants (e.g. different problems in a problem solving experiment)

Question 10

what are instructional variables?

Answer 10

Vary the type of instruction participants get (e.g. perform a memory task by trying to form a mental image of the item or not)

Question 11

what are subject variables?

Answer 11

Independent variables that are not directly manipulated by the experimenter such as natural groups (e.g. age groups, gender) or participant variables (e.g. political attitude, religious beliefs).

Question 12

what are the problems with subject variables?

Answer 12

• cannot be independently manipulated
• therefore causal inferences are problematic
• differences in the DV between groups can be caused by any other factor on which the groups differ.

Question 13

which groups are control group experiments made of?

Answer 13

• Experimental group: Gets a specific treatment or manipulation.
• Control group: Does not get an effective treatment or manipulation.

Question 14

what are problems with the dependent variable?

Answer 14

• ceiling effects
• floor effects

Question 15

what are ceiling effects?

Answer 15

The average scores for the DV are so high that no difference can be determined between conditions.

Question 16

what are floor effects?

Answer 16

The average scores for the DV are so low that no difference can be determined between conditions.

Question 17

what is the regression to the mean?

Answer 17

There is a statistical tendency for people who score extremely low or high on a test to score closer to the middle the next time.

Question 18

what can be done to control extraneous variables? (5)

Answer 18

• Keeping the variable constant across experimental groups (e.g. only include people with specific face recognition abilities)
• Build the EV into design to investigate it (e.g. including face recognition abilities as a factor in the design)
• Matching the groups regarding the EV
• Random assignment to experimental groups
• Statistically controlling the variable (e.g. measuring the extraneous variable and statistically considering the influence)

Question 19

what are the forms of validity in experimental research?

Answer 19

• external validity
• internal validity

Question 20

what is the external validity?

Answer 20

The extent to which one can generalize the findings of a study to other situations, people, settings and measures.

Question 21

what are the main criticisms of external validity?

Answer 21

• participants
  → Most studies in cognitive and social psychology are carried out with participants from WEIRD (Western, Educated, Industrialized, Rich, and Democratic) societies.
• Experimental setting
  → Experimental settings are artificial and completely detached from real life. They lack ecological validity.

Question 22

what is internal validity?

Answer 22

Internal validity is the degree of confidence that the causal relationship you are testing is not influenced by other factors or variables

Question 23

threats to internal validity (studies extending over time)

Answer 23

• History: An unrelated event influences the outcomes
• Maturation: The outcomes of the study vary as a natural result of time.
• Instrumentation: Different measures are used in pre-test and post-test phases
• Testing: The pre-test influences the outcome of the post-test.

Question 24

threats to internal validity (participant problems)

Answer 24

• Selection bias: Groups are not comparable at the beginning of the study
• Attrition: Dropouts from participants

Question 25

what is the trade-off between internal and external validity?

Answer 25

A causal relationship can be tested in an artificial lab setting or in the ‘real world’. A lab setting ensures higher internal validity because external influences can be minimized. However, the external validity diminishes because a lab environment is different than the ‘outside world’ (that does have external influencing factors).

Question 26

what are between subject designs?

Answer 26

Groups of participants are assigned to the experimental conditions

Question 27

what are the advantages of between-subject designs?

Answer 27

- Avoid carry-over effects - Require less testing time because each participant is only exposed to one experimental condition/treatment

Question 28

what are the disadvantages of between-subject designs?

Answer 28

- Require more participants - Are sensitive to sampling biases

Question 29

Which analysis can be used? Randomized Treatment and Control (2 groups) with Posttest-Only Design (between-participant design)

Answer 29

independent sample t-test

Question 30

which analysis can be used to compare means between experimental and control group conditions for significant differences?

Answer 30

independent sample t-test

Question 31

which analysis can be used? Randomized Multiple Treatments and Control with Post-test-Only Design

Answer 31

one-way anova

Question 32

which analysis can be used to compare means across different experimental conditions for significant differences?

Answer 32

one-way anova

Question 33

which analysis can be used? Randomized Multiple Treatments and Control with Pre-test and Post-test Design.

Answer 33

3x2 repeated-measures ANOVA

Question 34

which analysis can be used to compare means across different experimental conditions for significant differences?

Answer 34

3x2 repeated-measures ANOVA

Question 35

what are quasi-experimental designs?

Answer 35

Non-random assignment to conditions.

Question 36

what is the ethical aspect of quasi-experimental designs?

Answer 36

For ethical reasons it is often not possible to experimentally manipulate specific factors.

Question 37

which analysis can be used? Simple ex-post-facto design

Answer 37

independent sample t-test

Question 38

which analysis can be used to compare means between experimental and control group conditions for significant differences?

Answer 38

independent sample t-test

Question 39

what are within-subject designs?

Answer 39

Each participant is exposed to each level of the independent variable.

Question 40

what are advantages of within-subject designs?

Answer 40

Within-subject designs reduce error related to individual differences.

Question 41

what are disadvantages of within-subject designs?

Answer 41

* Major problem are carry-over effects from one condition to the other. * Require more testing time for each participant

Question 42

what are carry-over effects?

Answer 42

Performance in one condition might influence performance in the other condition (e.g. if participants have to do an implicit and explicit task on stimuli)

Question 43

what is counterbalancing?

Answer 43

Manipulating the sequence of conditions.

Question 44

what is across subject counterbalancing?

Answer 44

The order of conditions is manipulated across participants. Participant 1: A then B Participant 2: B then A

Question 45

what is reverse counterbalancing?

Answer 45

Each participant gets both orders of conditions in a reversed way. Participant 1: ABBA

Question 46

what is experimenter bias?

Answer 46

Any systematic errors in the research process or the interpretation of its results that are attributable to a researcher’s behavior, preconceived beliefs, expectancies, or desires about results.

Question 47

what are measures against experimenter bias?

Answer 47

* Trying to standardize the experiment as much as possible * Double blind experiments: the experimenter doesn‘t know the assignment of participants to conditions

Question 48

what is participant bias?

Answer 48

The influence that research participants’ knowledge about aspects of the research has on their responses to experimental conditions and manipulations

Question 49

what is the Hawthorne effect?

Answer 49

The effect on the behavior of individuals of knowing that they are being observed or are taking part in research. - Evaluation apprehension (participants want to be positively evaluated)

Question 50

what is the demand effect?

Answer 50

Effects induced by demand characteristics (cues that might indicate the research objective) to participants. These cues can lead participants to change their behaviors or responses based on what they think the research is about.

Question 51

what are ways to deal with demand effects?

Answer 51

- Avoiding any demand characteristics: One should avoid cues that indicate the aim of the study. - Using placebo groups: Participants think they are in the treatment group but in fact they are not. - Deception: Giving participants false information about the purpose of the experiment. -> Deception is ethically problematic - Manipulation check: Asking participants what they think the experiment was about.