Teaching Research Methods – Extraneous Variables

The Mad Psychologist!

Relevant for GCSE and A-Level

As you may have already determined by my previous posts, I really enjoy teaching Research Methods. Whilst it can be dry, it can be made into a very practical topic where students design their own studies, analyse the design and results of studies, as well as evaluate and improve research designs. Not only does making these lessons practical make them more enjoyable, it has the added benefit of improving students’ exam answers because they can think more effectively from a researcher’s perspective and justify their decisions.

One particular area of the topic that students always seem to struggle with is extraneous variables and how to control them. The volume of key terminology can be overwhelming, especially for the bottom end. From speaking to my students, the main sticking point is being able to identify the extraneous variables in different examples. They’re confident that they can define the key terms, but applying them is much more difficult. With this content now being introduced at GCSE as well, it is really important that students feel confident using these terms in different contexts. To help with this, I use a strategy that involves me running an experiment really badly so that students can identify and suggest how to control the extraneous variables – the Mad Psychologist!

A few things to note before we get into the strategy:

1. This is an activity designed for the new Edexcel GCSE Psychology specification, but it can be used for AQA A-Level without tweaking due to the similarity of the content on the specifications.

2. At A-Level, I use flipped learning (http://flmpsychologypedagogy.blogspot.co.uk/2017/10/flipped-learning-part-1-setting-tasks.html). This means that students have learned the key terminology before the lesson. Their understanding is assessed through a game of Articulate (http://flmpsychologypedagogy.blogspot.co.uk/2017/10/flipped-learning-part-2-assessing.html) before beginning this activity.

3. My school uses a bronze, silver, gold medal system for differentiation. This can be used to give students choice (so they can complete either the bronze, silver or gold task) or they can work their way up the medals to earn gold and go from the 'easiest' task to the most 'difficult.' We then use challenge tasks to really extend the thinking of the top end.

4. The activity requires no printing, so is an ideal one for departments with small budgets.

Step 1 – Assigning your participants to conditions

Students are told that they will be taking part in an experiment. They are given one minute to divide themselves into two groups. This introduces participant variables as students will choose to be with their friends. It’s really interesting that students are often friends with people who are roughly the same ability as them, and this is always mentioned in their analyses.

Step 2 – Running the experiment

For the experiment, I use the Stroop experiment. It’s nice and straightforward to have the two conditions on two slides, and it’s easy to tweak to introduce lots of extraneous variables. Typically, I will introduce the following:

• Lack of standardisation and investigator effects - condition 1 (colour words written in the correct colour) are given detailed instructions about the task and exactly what they have to do, whilst condition 2 (colour words written in the incorrect colour) are simply told that they will be 'doing the same thing as the previous condition, but it's more difficult.' Condition 2 has more words (and different words) to condition 1. Condition 2 has more colours than condition 1.
• Demand characteristics - condition 1 are not told why the study is happening, only what they have to do. Condition 2 are told the aim before they begin.
• Situational variables - silence is insisted upon for condition 1, but not for condition 2.

Other extraneous variables can be added in easily, such as using a stopwatch for one group, but using a clock on the wall for the other. Participants in condition 1 could be tested separately whilst condition 2 could be tested collectively.

Step 3 - Analysing and improving the experiment

Students then work in pairs to analyse the design of the experiment using the success criteria (see right). Again, this can be quite flexible as the questions can be modified to suit your students and what they have really struggled with. I get students to refer back to concepts we have previously covered, such as ethical issues and writing hypotheses so that they are synthesising their Research Methods knowledge.

During the feedback, students share their ideas collaboratively and we link the key terms to their examples. My GCSE students are typically very good at creating ways to control the extraneous variables they have identified, and I extend these to include counterbalancing, randomisation, and single- and double-blind designs. As my A-Level students have completed flipped learning on this before the lesson, they are able to suggest these ideas themselves and explain how they overcome each extraneous variable they have identified.

This activity really helps students to apply the extraneous variables to a new context and makes them much more confident with exam questions afterwards. My students were much better at thinking like a researcher and identifying how variables that hadn’t been considered may affect the results, as well as how the variables could (and should) have been controlled. Their explanations of concepts such as randomisation were much more detailed as they felt more confident explaining the process in full having already applied it successfully. Give it a go and let me know how it works out.