types of experiment

Laboratory experiment

Conducted and highly controlled environments where a researcher manipulates the independent variable and records the effects of the dependent variable.

• Laboratory experiment strengths

There is high control over confounding and extraneous variables which means there’s high internal validity. And replication is possible because of high level of control therefore it is easy to check results of the study.

Laboratory experiment limitations

May lack generalisability because a lab experiment may be artificial and not like everyday life. Low external validity because participants behaviour is likely to not be the same as in a natural setting. Demand characteristics because they are aware they are being tested in a lab therefore does not represent every day experience.

Field experiment

An experiment that takes place in a natural setting where the researcher manipulates the independent variable and records the effect of the dependent variable. It is a more everyday setting.

Field experiment strengths

Higher maintain realism because the environment is more natural. So produces behaviour that is more valid and authentic. Has high external validity because participants may be unaware that they are being studied.

Field experiment limitation

Due to loss of control of cofounding and extraneous variables this means cause an effect between independent independent variable is much more difficult to establish. There are also important ethical issues and if participants are unaware they are being studied they cannot consent to being studied which is an invasion of privacy.

Natural experiment

The researcher does not have control over the independent variable and cannot change it someone or something else causes the independent Variable vary. The independent variable is natural. The researcher records the effect on a dependent variable they have decided on.

Natural experiment strength

Provides opportunities for research that may not otherwise be undertaken for ethical reasons for example Romanian orphans. They have high external validity because they involve the study of real world issues and problems.

Natural experiment limitations

Naturally re occurring events only happen very rarely so there is a limited scope for generalisation of findings. Participants may not be randomly allocated to experimental conditions so the research might be less accurate on knowing whether the independent variable affected the dependent variable.

Quasi experiment

A study that has an independent variable based on an existing difference between people. No one has manipulated this variable. It’s simply exists for example studying phobias would have not come through an experimental manipulation.

Quasi experiment strengths and limitations

As it is carried out under controlled conditions, it shares the same strength as a lab experiment however there may be confounding variables. We cannot claim that the independent variable has caused any observed change.