Types of Experiments Flashcards
What are 4 types of experiments?
- Laboratory
- Field
- Natural
- Quasi
What is a lab experiment?
- Carried out in a controlled environment which allows the researcher to have high control over the IV and to control extraneous variables.
What are the strengths of lab experiments?
1: Control over extraneous variables/ establish cause and effect - The researcher can be confident that the IV is affecting the DV and can establish cause and effect.
Increases internal validity of the study.
2: Replicability - the researcher has a high degree of control and standardised procedures.
This allows the exact study to be repeated by other researchers.
This is a strength because if the same study is repeated and the same results are obtained, the study has high external reliability.
What are the limitations of lab experiments?
1: Demand characteristics & investigator effects are more likely to confound results - Ppts may find it easy to guess the aim of study and change their behaviour.
This is a limitation because it decreases the internal validity of the study.
2: Low ecological validity - Lab experiments tend to have low mundane realism.
The behaviour demonstrated in lab experiments may not reflect how ppts would behave outside the lab.
This is a limitation because it decreases external ecological validity of the study.
What is a field experiment?
-Carried out in a real-world setting rather than the laboratory.
- The experimenter still deliberately manipulates the IV.
- Ppts are in a natural environment and are usually “passers-by”
What are strengths of field experiments?
1: High ecological validity: Field studies are carried out in a real word setting and tasks given resemble real life ( high mundane realism).
Ppt’s behaviour is reflective of how they would behave in real life.
This is a strength because it increases external ecological validity .
2: Reduction of demand characteristics: Ppts are usually unaware that they are taking part in a study so their behaviour is not affected by DC and will be natural.
This is a strength because it increases the internal validity.
What are limitations of field experiments?
1: Low control over extraneous variables: It is difficult to have high control over extraneous variables in real life situations.
The researcher cannot be confident that the IV is affecting the DV so it is difficult to establish cause and effect.
This is a limitation because it reduces the internal validity of the study.
2: Difficult to replicate - Low control over extraneous variables means the replication of field experiments is more difficult.
This is a limitation because it is very difficult to test the external reliability of the results.
3: Unethical - Ppts are “passers-by” and do not know that they are part of the study.
This is a limitation because researchers cannot get informed consent.
Ppts cannot withdraw and may not be debriefed as they do not know they are
part of a study.
What is a natural experiment?
A type of experiment where the IV and DV occur naturally and the researcher measures the DV.
What are strengths of a natural experiment?
1: High ecological validity - IV and DV are naturally occurring so all behaviour being studied is natural.
This is a strength because it increases external ecological validity of the study.
2: Reduction of demand characteristics: Ppts are unaware that they are part of a study so their behaviour will not be affected by demand characteristics.
This is a strength because the study may be measuring natural behaviour increasing internal validity.
What are limitations of natural experiments?
1: Low control over extraneous variables - The researcher cannot be confident that the IV is causing the DV because the IV and DV are not manipulated.
This is a limitation because it reduces the internal validity of the study.
2: Difficult to replicate - Due to low control over extraneous variables, the replication of a natural experiment is more difficult than with lab.
This is a limitation because it is very difficult to test the external reliability of the results.
What is a quasi experiment?
A type of experiment where the IV is pre-existing/naturally occurring but the researcher manipulates the task that ppts are required to complete.
What are strengths of a quasi experiment?
1: Control over extraneous variables/establish cause and effect - QE take place in controlled conditions are the researcher manipulates the task that ppts undertake so they can be confident that the IV is affecting the DV and can establish cause and effect.
This is a strength because it increases the internal validity
2: Replicability - QE are conducted in a highly controlled condition with standardised procedure therefore replicable.
This is a strength because if the study is repeated and the same results are obtained, the study has high external reliability.
What are limitations of quasi experiments?
1: Potentially reduced ecological validity - Due to the task being manipulated, QE could have low mundane realism.
This is a limitation because it reduces external (ecological) validity.
2: Lower control over extraneous variables than a lab experiment - The researcher does not manipulate the IV so they cannot be certain that the IV is causing the DV or if other confounding variables are contributing.
This is a limitation because it reduces the internal validity.
