TYPES OF EXPERIMENT Flashcards
There are four types of experiments used by psychologists when conducting their studies. Name these four experiments.
- Laboratory experiments
- Field experiments
- Natural experiments
- Quasi-experiments
What is a laboratory (lab) experiment?
A laboratory experiment takes place in a controlled environment within which the researcher manipulates the IV and records the effect on the DV. Researchers maintain strict control over extraneous variables.
Do laboratory experiments have to be conducted in a lab?
Laboratory experiments are not always conducted in a lab environment. It could, for example, be conducted in a classroom where the conditions were well controlled.
What are the strengths associated with laboratory experiments?
Lab experiments have high control over extraneous variables. This means that the researcher can ensure that any effect on the DV is likely to be the result of manipulation of the IV. Thus, we can be more certain about demonstrating cause and effect (high internal validity).
Replication is more possible than in other types of experiment because of the high level of control. This ensures that new extraneous variables are not introduced when repeating an experiment. Replication is vital to check the results of any study to see whether the finding is valid and not just a one-off.
What are the weaknesses associated with laboratory experiments?
Lab experiments may lack generalisability. The lab environment may be rather artificial and not like everyday life. In an unfamiliar context participants may behave in unusual ways so their behaviour cannot always be generalised beyond the research setting (low external validity).
Participants are usually aware they are being tested in a lab experiment and this may also give rise to ‘unnatural’ behaviour (demand characteristics).
The tasks participants are asked to carry out in a lab experiment may not represent real life experience (e.g. recalling unconnected lists of words as part of a memory experience). Lab experiments are therefore thought to have low mundane realism.
What is a field experiment?
A field experiment is an experiment that takes place in a natural setting within which the researcher manipulates the IV and records the effect on the DV.
What are the strengths associated with field experiments?
Field experiments have higher mundane realism than lab experiments because the environment tis more natural. Thus, field experiments may produce behaviour that is more valid and authentic. This is especially the case as participants may be unaware they are being studied (high external validity).
What are the weaknesses associated with field experiments?
Field experiments have a lack of control over extraneous variables. This means cause and effect between the IV and the DV may be much more difficult to establish. Consequently, precise replication is not possible.
There are also important ethical issues. If participants are unaware they are being studied they cannot consent to being studied and such research might constitute an invasion of privacy.
What are natural experiments?
Natural experiments are when the researcher takes advantage of a pre-existing independent variable. This kind of experiment is called ‘natural’ because the variable would have changed even if the experimenter was not interested. It is the IV that is natural, not necessarily the setting. This therefore means that a natural experiment could be conducted in a laboratory.
How can one differentiate between a field experiment and a natural experiment?
In a field experiment the setting is natural, whereas in a natural experiment the IV is natural.
What are the strengths associated with natural experiments?
Natural experiments provide opportunities for research that may not otherwise be undertaken for practical or ethical reasons, such as the studies of institutionalised Romanian orphans.
Natural experiments often have high external validity because they involve the study of real-life issues and problems as they happen, such as the effects of a natural disaster on stress levels.
What are the limitations associated with natural experiments?
A naturally occurring event may only happen very rarely, reducing the opportunities for research. This also may limit the scope for generalising findings to other similar situations.
Participants may not be randomly allocated to experimental conditions. This means the researcher might be less sure whether the IV affected the DV. For example, in the study of Romanian orphans the IV was whether children were adopted early or late. However, there were lots of other differences between these groups, such as those who were adopted late may also have been the less attractive children who no one wanted to adopt.
What are Quasi-experiments?
Quasi-experiments have an IV that is based on an existing difference between people (e.g. age or gender). No one has manipulated this variable, it simply exists.
Outline one strength of a quasi-experiment.
Quasi-experiments are often carried out under controlled conditions and therefore share the strengths of a lab experiment.
Outline one limitation of a quasi-experiment.
Quasi-experiments, like natural experiments, cannot randomly allocate participants to conditions and therefore there may be confounding variables.
