Research that is planned and controlled by the examiner. in which the experimenter (subject) acts on an isolated object (objects) and records the change in its state. It is conducted in order to test the hypothesis of a causal relationship between the effect (independent variable) and changes in the object’s state (dependent variable). In psychology. An experiment is a joint activity between a subject and an examiner to study the psychological characteristics of the subject by observing their behavior during experimental tasks.