Experimental design

Question 1

What types of variables do you know?

Answer 1

Independent, dependent, extraneous (e.g., confound)

Question 2

Types of independent variables?

Answer 2

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

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

Instructional variables:
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 3

Problems can occur with the dependent variable, e.g., ceiling and floor effects. What do they mean?

Answer 3

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

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

Question 4

What are subject variables?

Answer 4

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 5

What are quasi-experimental designs?

Answer 5

Non-random assignment to conditions.
Example: Investigating the role of critical life events on stress level.
Ethical aspect: For ethical reasons it is often not possible to experimentally manipulate specific factors.

Question 6

What are Within-subject designs?

Answer 6

Each participant is exposed to each level of the independent variable.
* Within-subject designs reduce error related to individual differences.
* Major problem are carry-over effects from one condition to the other.
* Require more testing time for each participant

Question 7

What’s the difference between implicit and explicit tasks?

Answer 7

Memory tasks can be divided into two categories, explicit and implicit

Explicit: it is clear to the person being tested that he or she is supposed to retrieve information from memory.

Implicit: Memory needed to do the task, but subject isn’t trying to retrieve information from memory.

Question 8

In experimental research, there are two forms of validity: Internal and external. What is the difference?

Answer 8

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

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

Question 9

What is the Hawthorne effect?

Answer 9

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)