Overview
This lecture explains the concepts of independent and dependent variables in psychology, using clear definitions and a plant growth experiment as an example.
Independent and Dependent Variables
- The independent variable is the experimental factor that is manipulated or changed by the researcher.
- The dependent variable is the outcome that may change in response to changes in the independent variable.
- In experiments, most variables are kept constant to accurately test the effect of the independent variable.
- Only one variable (the independent variable) should be changed to observe its specific impact on the results.
Example: Plant Growth Experiment
- The researcher wants to test the effect of fertilizer on plant growth.
- Sunlight and water are kept the same for all plants to control these factors.
- The amount or percentage of fertilizer given to the plants is the variable that is changed (independent variable).
- After a set period, the growth of the plants is measured (dependent variable).
- Plant growth is the outcome being measured to determine if fertilizer makes a difference.
Key Terms & Definitions
- Independent Variable — the factor in an experiment that is deliberately changed to observe its effect.
- Dependent Variable — the factor that is measured in an experiment; it is expected to change in response to the independent variable.
- Control Variables — factors that are kept the same across all experimental groups to ensure a fair test.
Action Items / Next Steps
- Review the definitions of independent and dependent variables.
- Practice identifying independent and dependent variables in sample experiments.