MCAT® ExamPsychological, Social, and Biological Foundations of BehaviorEasy
A researcher is investigating the impact of classical music on plant growth. They expose one group of plants to classical music for 8 hours daily, while a control group grows in silence. All other environmental factors, such as light, water, and temperature, are kept constant. After two months, the researcher measures the average height of the plants in both groups. Which of the following best describes the independent variable in this experiment?
- AThe type of music played (classical vs. silence)
- BThe average height of the plants
- CThe duration of music exposure (8 hours daily)
- DThe amount of light, water, and temperature
Show answer & explanationAnswer & explanation
Correct answer: A. The type of music played (classical vs. silence)
The independent variable is the factor that is intentionally manipulated or changed by the researcher to observe its effect on another variable. In this experiment, the researcher manipulates the presence or absence of classical music.
Why the other options are wrong
- B. This is the dependent variable, as it is the outcome being measured.
- C. This is a controlled aspect of the independent variable, not the variable itself.
- D. These are controlled variables, kept constant to ensure they do not influence the outcome.
Independent Variable
The variable that is changed or controlled in a scientific experiment to test its effects on the dependent variable.
- Manipulated by the researcher
- Causes a change in the dependent variable
- Often denoted as 'X' in graphs
Memory trick: IV is what I Vary, DV is what I Discover.