In the context of AP Psychology and the scientific method, which of the following best defines an experiment?

• A. A detailed observation of a single individual or group over an extended period of time without manipulation of variables.
• B. A method that involves collecting data through surveys or questionnaires to gather self-reported attitudes or behaviors.
• C. A research approach that examines the relationship between two variables without direct manipulation or control.
• D. A research method in which an investigator manipulates one or more variables to observe the effect on some behavior or mental process while controlling other relevant variables.

Answer: (D)

Verified step by step guidance

1. Understand the key components of an experiment in psychology: manipulation of variables, observation of effects, and control of other variables.
2. Recognize that an experiment involves an investigator actively changing one or more independent variables to see how they affect a dependent variable.
3. Identify that controlling other relevant variables (extraneous variables) is crucial to ensure that the observed effects are due to the manipulation and not other factors.
4. Differentiate an experiment from other research methods such as case studies (detailed observation without manipulation), surveys (self-reported data collection), and correlational studies (examining relationships without manipulation).
5. Conclude that the best definition of an experiment is a research method where the investigator manipulates variables to observe effects on behavior or mental processes while controlling other variables.