"A simple experiment is used to establish cause and effect, so this type of study is often used to determine the effect of a treatment. In a simple experiment, study participants are randomly assigned to one of two groups. Generally, one group is the control group and receives no treatment, while the other group is the experimental group and receives the treatment."
Though performing a psychological experiment is a long-standing method in psychology, it is not listed as a methodology choice in PsycINFO.
But it is easy to find studies that use experiments.
Create your search in PsycINFO, then pick Empirical studies as a methodology.
Then search experiment* in the Abstract. That will give you the use of the word experiment, experiments, or experimental in the abstract.
Then make your selection.
Read the methodology section of the full article to see how the experiment was done by the researchers.
Canadian journal of experimental psychology
Like experimental studies, the best way to find studies that use OBSERVATION or SURVEYS is to add either word in abstract to a topic search.
Observ* or Survey* in abstract