The way that an experiment is carried out can affect the results of the experiment, so we have to try and control potential variables. Let’s look at some of these variables and ways that we can control for them.
|Variable||Way to Control For It|
|Extraneous Variables, such as noise and distractions.||You can control for this by, for example, making sure the room is quiet and without distraction. OR you can ensure that all participants do the task at the same time and in the same place, so all of them experience the same environment.|
For example – We are conducting a memory experiment. Group 1 have to learn a list of ten words, sit for two minutes, then recall the words. Group 2 have to learn ten words, then sit for two minutes saying their 12 times tables backwards, then recall the words. We want to see if distraction affects the recall of the words.
So in an ideal world, group 1 would sit in a quiet room without distractions and do their task. Group 2 would also sit in another room and do their task – the only distraction should be saying their times tables backwards. Then we could compare the results and any difference should hopefully be because of the distraction of group 2 saying their times tables.
But say you put group 2 in a quiet room to do their task, but group 1 were in a room where a builder was outside drilling a hole in the wall. Both groups perform their tasks, but when we compare their results – are they fair? Group 1 was also distracted – by the builder.
So to ensure things like this don’t happen, we have to try and ensure that both groups experience the same conditions.
In the next blog, we will look at order effects and how to deal with them.