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examBoard: AQA
examType: GCSE
lessonTitle: Review and Practice - Variables
Variables are essential building blocks of psychological research. They're simply the things that can change or vary in an experiment. Understanding different types of variables helps us design better studies and make sense of research findings.
Key Definitions:
The independent variable is what the researcher deliberately changes or manipulates. Think of it as the "cause" in a cause-and-effect relationship. In an experiment, there are usually at least two conditions or levels of the independent variable that are compared.
Example: In a study about the effect of sleep on test performance, the amount of sleep (e.g., 4 hours vs. 8 hours) would be the independent variable.
The dependent variable is what researchers measure to see if it's affected by the independent variable. It's the "effect" in cause-and-effect. The DV is called "dependent" because its value depends on the independent variable.
Example: In our sleep study, the test scores would be the dependent variable, as we're measuring how they change depending on sleep duration.
Good psychological research requires careful control of variables to ensure valid results. When variables aren't properly controlled, they can lead to confounding effects that make results difficult to interpret.
These are unwanted variables that might affect your results. They come in several types:
If not controlled, these can become confounding variables that make it impossible to know if changes in the DV were caused by the IV or by these unwanted factors.
Researchers use several strategies to control unwanted variables:
To study variables scientifically, psychologists need to define them in measurable ways. This process is called operationalisation.
Operationalisation means turning abstract concepts into something concrete that can be measured. For example, you can't directly measure "anxiety," but you can measure:
Heart rate, blood pressure, sweating, cortisol levels
Questionnaires, anxiety scales, interviews, diaries
Fidgeting, avoidance behaviours, task performance
This famous study on eyewitness testimony shows variables in action:
This shows how even subtle changes in an IV (just one word!) can significantly affect the DV.
Different research methods handle variables in different ways:
Experiments actively manipulate the IV to see its effect on the DV. They offer the strongest evidence for cause and effect.
Example: Manipulating background music (IV) to see effects on memory recall (DV).
These don't manipulate variables but look at relationships between them. They have co-variables rather than IVs and DVs.
Example: Measuring social media use and depression levels to see if they're related.
When studying psychology, it's easy to make these common mistakes:
Let's practice identifying variables in research scenarios:
Researchers want to investigate whether getting a full night's sleep improves memory. They divide participants into two groups: one sleeps for 8 hours, the other for 4 hours. The next day, both groups take a memory test.
A researcher asks participants to either browse social media for 30 minutes or read a book for 30 minutes. Afterwards, they complete a mood questionnaire.
Understanding variables is crucial for:
Remember that good research carefully defines, manipulates, measures and controls variables to produce valid and reliable findings. When you're reading about psychological studies, always ask yourself: "What were the variables and how were they handled?"
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