Types of Variable

Let's take memory abilities and shoe size; these seem like completely random concepts. But what if they're not? For researchers to establish if there is a link between the two, they need to conduct empirical, valid and reliable scientific research. When researchers conduct psychological research, they are usually trying to find out the relationship between two variables. There are different types of variables in psychology research; let's explore these. 

Types of Variable Types of Variable

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Contents
Table of contents
    • We will start by looking at the types of variables in psychology research. We will explore some psychological variables examples to ensure you can identify the differences between the types of variables.
    • We will look at the types of extraneous variables in psychology, including the topics of situational variables: psychology and participant variables: psychology.
    • To finish off, we will discuss confounding variables: psychology.

    Types of Variables in Psychology Research

    In experimental scientific research, the researcher's goal is to provide evidence supporting a phenomenon regarding whether it exists or doesn't exist.

    Psychology research has three variables: independent (IV), dependent (DV), and extraneous variables. Let us take a look at the definition of each variable.

    The independent variable is the variable that is manipulated to test its effect on the dependent variable.

    The IV is what the researcher proposes as the cause of a phenomenon. Thus, by manipulating changes in the IV, the researcher can establish if the changes affect the DV.

    The researcher doesn't always have to manipulate the IV. Sometimes it can be naturally occurring. A researcher can't manipulate the sun, but it can measure how exposed the subject is to sunshine.

    Types of variable, bored child whilst doing homework, StudySmarterFig 1. - An example of a naturally occurring IV is the amount of homework done each day.

    Now let's move on to understand what the DV is.

    The dependent variable is the outcome that is measured.

    The DV is what the researcher expects to be the outcome/ changes that occur due to manipulating the IV; therefore, it is considered the effect.

    In experimental research, cause-and-effect can be determined as the researcher measures the IV and DV whilst controlling external influences.

    Psychological Variables Examples

    To help us understand the concept of IVs and DVs, let us take a look at some examples.

    Remember, the independent variable causes an effect on the dependent variable.

    Each example describes a hypothetical hypothesis and then identifies the IV and DV of the study.

    The amount of sleep students get will affect their exam scores.

    Independent variable: the amount of sleep

    Dependent variable: exam scores

    In this research design, the researchers may compare sleep-deprived versus non-sleep-deprived students' test scores.

    Playing piano music will help babies fall asleep faster.

    Independent variable: piano music

    Dependent variable: how fast babies fell asleep

    You can probably see the pattern, but in this study, the researchers may explore how long it took for babies to fall asleep who were listening to piano music versus those who were not.

    Extraneous Variables in Research

    Extraneous variables are variables that could unknowingly affect the dependent variable. In an experiment, the independent variable should be the only thing that affects the dependent variable. However, sometimes there may be other 'nuisance' variables that actually affect the dependent variable.

    A theoretical experiment investigated the effect of the IV; whether children received Kumon lessons or not on the DV; end-of-year-grades.' If the study found that children who received Kumon lessons received better grades than those who did not, the researcher can infer that Kumon may boost academic performance.

    However, there may be other variables we didn't consider that affected the dependent variable.

    Perhaps whether children attended a private or public school influenced their test scores (DV), their parent's educational background, the quality of teaching received in school, whether the children had test anxiety or just their general health on the day.

    These other variables that could affect the dependent variable are called extraneous variables.

    Types of Extraneous Variables in Psychology

    There are two basic types of extraneous variables: participant and situational variables.

    Let's look at both in more detail.

    Situational Variables: Psychology

    Situational variables are factors in the environment that could affect participants' performance. Some examples of these are the temperature of the room and the noise in the room.

    In our example experiment, music would be a situational variable and academic performance a participant variable.

    An example of how researchers can control situational variables is:

    • Standardisation is when the experiment procedure is the same for each participant, So all participants experience the same things when they undergo the study.

    When conducting a study, the researcher should give the same instructions to each participant; this usually involves the researcher reading from a script.

    And the participants should be tested in the same conditions, e.g., same time of day, temperature, same noise levels and in the same venue.

    The presence of situational variables reduces the validity of the experiment.

    Types of variable, girl listening to music whilst working, StudySmarterFig 2. - Music is an example of a situational variable.

    Participant Variables: Psychology

    Participant variables are individual traits of a participant that could affect their performance in the experiment. Some examples of these are gender, age, intelligence and socioeconomic status.

    There are a few different ways to reduce extraneous variables, these are:

    • Random allocation: this is exactly what the name implies. Participants are randomly allocated to a group instead of the experimenter assigning participants to groups.

    • Single or double-blind technique: a single-blind technique is when participants don't know what the experimental conditions are; this way, they won't behave in a way they think the experimenters would want and bias the results.

    A single-blind technique is when the participant doesn't know if they are in the control or experimental group.

    A double-blind technique is when participants and experimenters interacting with the participants both don't know who is in the experimental versus the control group (group not exposed to IV). So, researchers won't act in a manner that biases the results.

    Suppose a researcher would like to find out the effects of meditation on anxiety levels. One group is given a particular meditation recording to play and follow along each day. In contrast, the other group are taught some breathing exercises to do whenever they're feeling anxious.

    If the group that's given the meditation recording knows at the end of the experiment their group is supposed to feel more at peace with low anxiousness compared to the other group, this can be an issue. When reporting their feelings, they may deliberately say they're feeling great because they think that's what the researchers want.

    When participants guess the hypothesis and act accordingly, this issue is known as the Hawthorne effect, which reduces the research's validity.

    When looking at studies, there will usually always be some extraneous variable you can find. Recognising these extraneous variables will give you an edge in critically analysing studies, leading to extra marks in evaluation.

    Confounding Variables in Psychology Research

    A confounding variable is an extraneous variable related to the independent and dependent variables. I.e., a confounding variable is correlated with the independent variable and has a direct effect on the dependent variable.

    A high standard of research is ensured by taking into account confounding variables. In this way, researchers can be reasonably confident that the independent variable is the only thing affecting the dependent variable.

    Some ways to reduce confounding variables are:

    • Restriction: only recruiting participants with similar characteristics or qualities, such as only using females age 30 for a study.
    • Matching participants: in this method, one participant is matched with another, and these pairs are split into two groups. And only one of the groups experiences the IV, and the other doesn't.
    • Randomisation: in this method, the researcher randomly allocates participants to each group. In this way, any confounding factors should be evenly distributed between the groups, thus not affecting the independent and dependent variables.

    Randomisation is the ideal sampling method used in psychology as it involves the least research involvement.

    Usually, this technique uses number generators to assign participants to groups so that the researcher's subjective opinion doesn't influence the research.

    Types of Variable - Key takeaways

    • When researchers conduct psychological research, they are usually trying to find out the relationship between two variables.

    • The independent variable is the variable manipulated to test its effect on the dependent variable. And the dependent variable is the outcome that is measured.

    • Extraneous variables are variables that could unknowingly affect the dependent variable. And these reduce the validity of the findings.

    • There are two types of extraneous variables: participant variables and situational variables.

    • Some ways to reduce extraneous variables are standardisation, random allocation, and single or blind technique.

    Frequently Asked Questions about Types of Variable

    What are the three types of variables?

    In psychological research, the three types of variables are independent, dependent and extraneous variables.

    What are variables in psychological research?

    Variables are what are studied in research to try and establish a cause-and-effect relationship. Researchers try to find out if an independent variable affects a dependent variable. 

    What are situational variables in psychology?

    Situational variables are things in the environment that could affect participants’ performance. Some examples of these are the temperature of the room and the noise in the room. 

    What is the dependent variable in psychology? 

    The dependent variable is the outcome that is measured in the study.

    What is the independent variable in psychology?

    The independent variable is the variable that is manipulated to test its effect on the dependent variable.

    Test your knowledge with multiple choice flashcards

    Is this a participant or situation variable: academic performance?

    Which of the following is thought of as the cause of a phenomenon? 

    Which of the following is thought of as the effect of a phenomenon? 

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