Variables

In any experiment, psychologists need to identify and control variables — factors that can change or vary. Understanding variables is essential for designing valid experiments and interpreting results.

---

What is a Variable?

A variable is any factor that can change or vary in a study. In an experiment, the researcher manipulates one variable and measures its effect on another, while trying to keep all other variables constant.

---

Types of Variable

Independent Variable (IV)

The independent variable is the variable that the researcher deliberately changes or manipulates to see its effect on the dependent variable.

• It is the cause in the experiment
• It is what differs between the conditions
• Example: In a study on the effect of sleep on memory, the IV might be the amount of sleep (8 hours vs 4 hours)

Dependent Variable (DV)

The dependent variable is the variable that the researcher measures to see if it has been affected by the IV.

• It is the effect in the experiment
• It is the outcome or result
• Example: In the sleep study, the DV would be the score on a memory test

Extraneous Variables