Which of the following was a controlled variable in the practical?

• A. Different participants in different locations
• B. Different questionnaires for each participant
• C. Using the same questionnaire with the same questions
• D. Participants answering at different times

Answer: (C)

Using the same questionnaire with the same questions is critical for maintaining consistency across the experiment. This controlled variable ensures that every participant is assessed using the identical set of questions, thereby minimizing variability that could arise from differences in how questions are phrased or the types of questions asked. By standardizing the questionnaire, researchers can be more confident that any observed differences in responses are due to the experimental manipulation rather than differences in the measurement tool.

In scientific research, controlling variables is essential to ensure the validity of the findings. When the same questionnaire is used, it helps eliminate one potential confound, allowing the researcher to attribute any changes in participants' responses more directly to the variable being studied rather than extraneous factors linked to the questionnaire itself. This uniformity is vital in biological psychology where the nuances of responses can significantly influence interpretations of psychological processes.