Types of experiment Flashcards
Laboratory experiment
A controlled environment where extraneous and confounding variables (EVs and CVs) can be regulated.
Participants go to researcher.
The IV is manipulated and the effect on the DV is recorded.
What is one strength of a laboratory experiment?
EVs and CVs can be controlled.
This means the effect of EVs and CVs on the DV can be minimised.
Cause and effect between the IV and DV can be demonstrated (high internal validity)
What is a second strength of a laboratory experiment?
Can be more easily replicated.
Greater control means less chance that new EVs introduced.
This means that findings can be confirmed, supporting their validity.
What is one limitation of a laboratory experiment?
May lack generalisability.
The controlled lab environment may be rather artificial and participants are aware they are being studied.
Thus behaviour may not be ‘natural’ and can’t be generalised to everyday life (low external validity).
What is a second limitation of a laboratory experiment?
Demand characteristics may be a problem.
These are cues in the experimental situation that invite a particular response from participants.
The findings may be explained by these cues rather than the effect of the IV (lower internal validity).
Field experiment
A natural setting.
The researcher goes to participants.
The IV is manipulated and the effect on the DV is recorded.
What is one strength of a field experiment?
More natural environment.
Participants more comfortable and behaviour more authentic.
Results may be more generalisable to everyday life.
What is a second strength of a field experiment?
Participants are unaware of being studied.
They are more likely to behave as they normally do so the findings can be generalised.
The study has greater external validity.
What is one limitation of a field experiment?
More difficult to control CVs/EVs.
Observed changes in the DV may not be due to the IV, but to CVs/EVs instead.
It is more difficult to establish cause and effect than in the lab.
What is a second limitation of a field experiment?
There are ethical issues.
Participants may not have given informed consent.
This is an invasion of participants privacy, which raises ethical issues.
Natural experiment
The experimenter does not manipulate the IV - it does change, but the change is not made by the experimenter - someone or something else causes the IV to vary. The IV would have varied even if the experimenter wasn’t interested.
DV may be naturally occurring or may be devised by the experimenter in the field or lab.
What is one strength of a natural experiment?
May be the only practical/ethical option.
It may be unethical to manipulate the IV.
A natural experiment may be the only way casual research can be done for such topics.
What is a second strength of a natural experiment?
Greater external validity.
Natural experiments involve real world issues, such as the effect of a natural disaster on stress levels.
This means the findings are more relevant to real experiences.
What is one limitation of a natural experiment?
The natural event may only occur rarely.
Many natural events are one offs and this reduces the opportunity for research.
This may limit the scope for generalising findings to other similar situations.
What is a second limitation of a natural experiment?
Participants are not randomly allocated.
The experimenter has no control over which participants are placed in which condition as the IV is pre existing.
May result in CVs that aren’t controlled.
