Types of Variables (OCR GCSE Psychology): Revision Note
Exam code: J203
Independent variable (IV)
Psychologists study how different factors (or variables) affect behaviour
To investigate this, researchers change or manipulate one variable to see how it impacts another
The variable that the researcher changes or manipulates is called the independent variable (IV)
The IV can be something that the researcher implements, or it can be something naturally occurring, such as age, gender, or ethnicity
The IV is the cause in the cause-and-effect relationship — it’s what the psychologist does to see what happens
Examples of IVs
Whether participants learn a list of 20 words in silence or with loud rock music
Whether participants complete a jigsaw puzzle after 30 minutes of exercise or after no exercise
Whether children are exposed to an aggressive adult model or not exposed to one
Examiner Tips and Tricks
Remember that the IV and DV must be operationalised so the study can be replicated in exactly the same way. This means making them precise, specific and measurable.
For example, instead of stating the DV as 'ability to concentrate', you could operationalise concentration as the number of correct words recalled from a list in two minutes.
Dependent variable (DV)
The dependent variable is what the researcher measures to see what effect has occurred due to changes in the IV
It represents the effect in the cause-and-effect relationship
The DV must always be quantitative (numerical), so it can be measured specifically (i.e. operationalised), analysed and displayed in graphs
The DV should make logical sense based on the IV
If the IV is music vs silence, then the DV might be “number of words recalled correctly”
Examples of DVs
The number of items recalled from a list of 20 words
The time taken (in seconds) to complete a jigsaw puzzle
The number of imitative acts of aggression performed during a 20-minute observation
Examiner Tips and Tricks
As with all key terminology, try not to confuse the independent and dependent variables.
Remember: the DV depends on the IV. If you forget which is which, think “the dependent variable depends on what the independent variable has done.”
Extraneous variable (EV)
Extraneous variables (EVs) are any other factors (apart from the IV) that could influence the DV and affect the results
They can make it harder to tell whether the IV truly caused the change in the DV if the researcher does not control them
Psychologists often try to keep EVs the same across all conditions using standardisation
Examples of EVs
Time of day: some participants may perform better in the morning than in the afternoon
Temperature: a room that’s too hot or cold may affect concentration
Mood: a participant’s emotions (e.g. feeling tired, upset, or excited) can influence how well they perform
Researcher characteristics: the researcher might smile at some participants more than others
Worked Example
Here is an example of an A02 question you might be asked on this topic.
AO2: You need to apply your knowledge and understanding, usually referring to the ‘stem’ in order to do so (the stem is the example given before the question).
Professor Gunner believes that drinking cola before a football match improves players’ ability to score penalties. He decides to test this by comparing the performance of players who drink cola with those who do not.
Q. Identify the independent variable in this investigation.
[1 mark]
Model answer:
The IV is whether the football players drink cola or do not drink cola before attempting the penalties [1 mark].
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