Which of the following is a technique to improve internal validity in psychological research?

• A. Using naturalistic observation to collect data
• B. Random assignment of participants to experimental conditions
• C. Increasing the sample size to enhance generalizability
• D. Conducting a meta-analysis of previous studies

Answer: (B)

Verified step by step guidance

1. Understand that internal validity refers to the extent to which a study can establish a causal relationship between variables, ensuring that the observed effects are due to the manipulation of the independent variable and not other factors.
2. Recognize that techniques to improve internal validity focus on controlling confounding variables and ensuring that groups are comparable at the start of the experiment.
3. Evaluate each option: Naturalistic observation is a data collection method but does not control for confounding variables, so it does not primarily improve internal validity.
4. Increasing sample size improves generalizability (external validity), not internal validity, because it affects how well results apply to other populations rather than controlling confounds within the study.
5. Random assignment of participants to experimental conditions is a key technique to improve internal validity because it helps ensure that participant characteristics are evenly distributed across groups, reducing confounding variables and allowing for clearer causal conclusions.