Which of the following is NOT an example of an experiment in psychology?

• A. A scientist tests whether changing the lighting in a room affects participants' mood.
• B. A researcher randomly assigns participants to two groups and tests the effect of a new drug on memory performance.
• C. An investigator manipulates the amount of sleep participants get and measures their reaction times.
• D. A psychologist observes children playing in a park without manipulating any variables.

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the definition of an experiment in psychology. An experiment involves the manipulation of one or more independent variables and the measurement of their effect on dependent variables, with participants typically randomly assigned to different conditions.
2. Step 2: Review each option to identify whether it involves manipulation of variables and random assignment, which are key features of an experiment.
3. Step 3: Analyze the first option: changing the lighting in a room to see its effect on mood involves manipulation of an independent variable (lighting) and measuring a dependent variable (mood), so it qualifies as an experiment.
4. Step 4: Analyze the second option: randomly assigning participants to groups and testing a drug's effect on memory involves manipulation and random assignment, so it is an experiment.
5. Step 5: Analyze the third option: manipulating sleep amount and measuring reaction times also involves manipulation and measurement, so it is an experiment. The last option, observing children playing without manipulating variables, is a naturalistic observation, not an experiment.