Variables in research

Research is an integral part of psychology and is carried out in various different areas of interest, such as child development, abnormal behaviour, social influence and how the brain works, to name but a few.

Researchers have to approach their research in similar ways so that it helps to ensure consistency in findings and helps others to replicate their studies so that their findings can be justified or challenged.

The way in which research is approached is by following certain procedures, which are planning the research, carrying it out and then analysing what is found.

Once the researcher has produced a hypothesis (this is discussed later in this unit), they must ensure that the variables within the hypothesis are appropriately managed.

A hypothesis, which predicts a difference between something (‘there will be a difference between men and women’s ability to drive a car after not sleeping for 24 hours’), will have two key variables, which are:

• An independent variable
• A dependent variable

In research, the researcher is looking to find out if the dependent variable is affected by the independent variable, as explained below:

What is an independent variable?

This variable is what the researcher manipulates or changes. So, in the instance of the example above regarding driving a car, the independent variable is if the participant is a man or a woman, as this is the thing that changes and it is this that determines if the dependent variable will be affected. Other examples might include:

• Children who have a sibling will be more empathetic than children who do not; the independent variable here is if a child has a sibling or if they do not
• There will be a difference in obedience if participants are given an instruction by someone wearing a uniform; the independent variable here is if the person giving an instruction is wearing a uniform or not
• Participants will remember more sequences of letters if they are organised meaningfully than if they are random; the independent variable here is if the letters are organised or random

What is a dependent variable?

The dependent variable is what the researcher measures in order to find out if it has been affected by the independent variable. It is the thing that does not change.

In the examples below:

• Children who have a sibling will be more empathetic than children who do not; the dependent variable here is the level of empathy
• There will be a difference in obedience if participants are given an instruction by someone wearing a uniform; the dependent variable here is the level of obedience
• Participants will remember more sequences of letters if they are organised meaningfully than if they are random; the dependent variable here is the amount of letter sequences that are remembered

It is important that both variables are operationalised by the researchers so that they can be tested and measured. When variables are operationalised, this means that they are very specific and detailed so that other researchers can see what was measured, what was changed and how this happened. Operationalising variables also means that the same research can be carried out in future.

What are extraneous variables?

The best way to find out if the independent variable affects the dependent variable is to carry out an experiment in a laboratory. This is because it is very difficult to control variables in a real-life setting and therefore decide if it is they which are having an effect on the dependent variable.

Variables which may have an effect on the outcome of an experiment are called extraneous variables, and researchers must ensure that these are identified, isolated and controlled as fully as possible so that they do not affect the dependent variable.

For example, imagine that we carried out the experiment with letter sequences. We found participants and put them in a room and then did the memory test with them without any consideration of extraneous variables at all. We would likely find that the two main types of extraneous variable that affected our experiment were:

• Situational
• Participant

Situational variables

These are aspects of the environment in which the experiment takes place that may affect its outcome. So, in our example, these might be:

• Outside noise
• Room temperature
• Poor lighting
• The smell of the room

Any of these variables might be distracting to participants and their performance in the experiment might be affected because of them. Researchers may be left asking if participants did do badly on the memory task in one of the conditions (random or organised letters) because of the arrangement of the letters or was it because when they did that part of the task, there was a loud noise outside and everyone was distracted by this?

Participant variables

As the name suggests, a participant variable is one that concerns the participant themselves. Some examples of participant variables include:

• Mood
• Intelligence
• Anxiety levels
• General levels of concentration
• Demand characteristics (where the participant will change their answer to match what they think the researcher wants to hear)
• Age
• Personality

In our experiment, if we did not control participant variables, we may unintentionally have recruited people with exceptional memories whose results will not be representative of a larger population