Dependent Variable in Experiments

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The dependent variable is the variable that is being measured or tested in an experiment. For example, in a study looking at how tutoring impacts test scores, the dependent variable would be the participants' test scores, since that is what is being measured.

In a psychology experiment, researchers are looking at how changes in the independent variable cause changes in the dependent variable.

One way to help identify the dependent variable is to remember that it depends on the independent variable. When researchers make changes to the independent variable, they then measure any resulting changes to the dependent variable.

Examples of Dependent Variables

As you are learning to identify the dependent variables in an experiment, it can be helpful to look at examples. Here are just a few examples of psychology research using dependent and independent variables.

  • A researcher is interested in studying how the amount of time spent studying influences test scores. In this example, the amount of studying would be the independent variable and the test scores would be the dependent variable. The test scores vary based on the amount of studying prior to the test. The researcher could change the independent variable by instead evaluating how age or gender influence test scores.
  • A health psychologist wants to learn more about how stress influences memory. In this example, the dependent variable might be test scores on a memory test and the independent variable might exposure to a stressful task.
  • A psychologist is interested in studying how a therapeutic technique influences the symptoms of psychological disorders. In this case, the dependent variable might be defined as the severity of the symptoms a patient is experiencing, while the independent variable would be the use of this specific therapy method.
  • In a psychology experiment, researchers want to discover if listening to classical music helps students earn better grades on a math exam. In this example, the scores on the math exams are the dependent variable and the classical music is the independent variable.
  • Researchers are interested in seeing how long it takes people to respond to different sounds. In this example, the length of time it takes participants to respond to a sound is the dependent variable, while the sounds are the independent variable.
  • Researchers want to know whether first-born children learn to speak at a younger age than second-born children. In this example, the dependent variable is the age at which the child learns to speak and the independent variable is whether the child is first- or second-born.
  • Researchers are interested in looking at how alcohol use influences reaction times while driving. The amount of alcohol a participant ingests is the independent variable, while their performance on the driving test is the dependent variable.

How to Identify the Dependent Variable

Experiments can range from simple to quite complicated, so sometimes it can be a bit confusing to learn how to identify the independent and dependent variables. Here are a few things you can do to help you remember which is which:

  • Which variable is the experimenter's measuring? If it is something that varies in response to changes in another variable, it is a dependent variable. In many psychology experiments and studies, the dependent variable is a measure of a certain aspect of a participant's behavior.
  • In an experiment looking at how sleep impacts test performance, the dependent variable would test performance because it's a measure of the participants' behavior.
  • The dependent variable is dubbed dependent because it is thought to depend in some way on the variations of the independent variable.
  • Which variable does the experimenter's manipulate? The independent variable is deemed independent because the experimenters are free to vary it as they need.

Choosing Dependent Variables

So, how do researchers determine what a good dependent variable will be? Stability is often a good sign of a quality dependent variable. If the same experiment is repeated with the same participants, conditions, and experimental manipulations, the effects on the dependent variable should be very close to what they were the first time around.

It is also important to remember that while some studies may only have one dependent variable and one independent variable, it is also possible to have several of each type of variable. For example, researchers might want to learn how variables in a single independent variable affect several distinct dependent variables.

For example, imagine an experiment where a researcher wants to learn how the messiness of a room influences people's creativity levels. However, the research might also want to see how the messiness of a room might influence a person's mood. The messiness of a room would be the independent variable, but the study would have two dependent variables: levels of creativity and mood.

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  1. Steingrimsdottir HS, Arntzen E. On the utility of within-participant research design when working with patients with neurocognitive disordersClin Interv Aging. 2015;10:1189-1199. doi:10.2147/CIA.S81868

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