Types of Experiments

Question 1

What is a laboratory experiment?

Answer 1

An experiment that takes places in a controlled environment within which the researcher manipulates the IV and records the effect on the DV, whilst maintaining strict control of extraneous variables.

Question 2

Field experiment:

Answer 2

An experiment that takes place in a natural setting within which the researcher manipulates the IV and records the effect on he DV.

Question 3

Natural experiment:

Answer 3

An experiment where the change in the IV is not brought about by the researcher but would have happened even if the researcher had not been there. The researcher records the effect on the DV.

Question 4

Quasi-experiments:

Answer 4

A study that is almost an experiment but lacks key ingredients. The IV has not been determined by anyone, the variables simply exist. Strictly speaking this is not an experiment.

Question 5

Lab experiments: Pros

Answer 5

1. High control over extraneous variables and ensures that ay effect on the DV is due to the manipulation of the IV.
2. High internal validity
3. Replication, so you can see that the findings are valid.

Question 6

Lab experiments: Cons

Answer 6

1. May lack generalisability because the lab may be artificial.
2. People may behave in unusual ways in an unfamiliar context, behaviour cannot be generalised beyond the lab, low external validity.
3. Participants are usually aware that they are being tested in a lab experiment, demand characteristics.
4. The tasks participants are asked to carry out in a lab experiment may not represent real life- low mundane realism.

Question 7

Field experiments: Pros

Answer 7

1. Higher mundane realism than lab experiments.
2. Produce behaviour that is more valid and authentic.
3. Unaware they are being studied, high external validity

Question 8

Field experiments: Cons

Answer 8

1. Loss of control of extraneous variables.
2. The effect between the IV and the DV in field studies may be more difficult to establish.
3. Precise replication is often not possible.
4. Ethical issues, if they are unaware they are being studied they cannot consent to being studied, might constitute an invasion of privacy.

Question 9

Natural experiments: Pros

Answer 9

1. Provide opportunities for researcher that may not otherwise be undertaken for practical or ethical reasons, such as studies of institutionalised Romanian orphans.
2. High external validity, they involve the study of real-life issues and problems as they happen.

Question 10

Natural experiments: Cons

Answer 10

1. A naturally occurring event may only very rarely, reducing the opportunities for research. Limit the scope for generalising findings.
2. Pps may not be randomly allocated to experimental conditions, less sure if the Iv will affect the DV.
3. For example, in the study of Romanian orphans the IV, was whether they were adopted early or late.
4. However there were many differences between the groups.

Question 11

Quasi-experiments: Pros

Answer 11

1. Carried out under controlled conditions and therefore share the strengths of a lab experiments.

Question 12

Quasi-experiments: Cons

Answer 12

Cannot randomly allocate pps to conditions and there may be confounding variables.