Which type of experiments take place in a laboratory, with external variables excluded as far as possible?

• A. Field experiments
• B. Laboratory experiments
• C. Case study
• D. Hawthorne or Observer Effect

Answer: (B)

Laboratory experiments are conducted in a controlled setting where researchers can minimize external variables as much as possible. By standardizing procedures and controlling factors like lighting, temperature, noise, and equipment, and by randomly assigning participants to conditions, they isolate the effect of the independent variable on the dependent variable. This tight control strengthens internal validity and makes it easier to draw causal conclusions. In contrast, field experiments take place in real-world environments, where many external variables are harder to control, balancing practical realism with causal precision. A case study focuses on an in-depth look at a single case or a small number of cases and isn’t an experiment at all. The Hawthorne effect refers to changes in behavior caused by the awareness of being observed, not a type of experimental setting.