What is the essence of an experiment in psychological research?

An experiment in psychological research is characterized by the active manipulation of one or more independent variables by the researcher to observe the effects on a dependent variable. This controlled approach allows researchers to establish cause-and-effect relationships, distinguishing it from other research methods.

In an experimental design, random assignment is often employed to ensure that differences between groups are minimized, which helps in making valid inferences about the effects of the manipulated variable. This ability to manipulate variables and control for extraneous factors is what gives experiments their strong internal validity.

While the other options present valid research methods, they do not fit the definition of an experiment. Surveys focus on gathering subjective reports from participants rather than manipulating variables. Observational studies aim to record behaviors as they occur naturally without intervention, and retrospective analyses look back at previously collected data rather than actively engaging with variables in real-time. Therefore, option C captures the essence of an experiment effectively by highlighting the manipulation of variables to observe their effects.