How to avoid the biggest mistake in IAs
Linking your experiment to the theory

Travis Dixon Internal Assessment (IB) Leave a Comment

Forgetting to link the theory to the investigation is the biggest mistake in IAs - here's how to avoid it!
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The most common mistake I’ve seen in IAs with the new curriculum is the lack of focus on the background theory or model. Students spend all their time and energy on the original study they’re replicating, that they completely overlook this crucial element. In this blog post (and video), (and in the video below) I want to show you an easy way you can make sure your investigation for the IA is linked to your theory/model. 

You can download a step-by-step guide to the IB Psych IA.

To get full marks for the introduction,  you must describe a relevant theory or model that can explain the results of your original study. If it doesn’t have a name, it’s not an appropriate theory or model. Common examples include:

  • Schema theory
  • Multi-store model
  • Working memory model
  • Dual processing model
  • Levels of processing model

As well as theories or model, a well-known hypothesis or effect is also acceptable. For example:

  • The facial feedback hypothesis
  • Mozart effect
  • Misinformation effect
  • Anchoring effect
  • Stroop effect

While it might be enough just to write about the effect, I encourage my students to find a theory or model that can explain the effect. For example, using the dual processing model to explain the anchoring effect or working memory model to explain the Mozart effect (if lyrics vs. no lyrics are tested).

Read more:

To make things easier, I’m going to use the term original study to refer to the study that the experiment is based on (e.g. Loftus and Palmer would be the original study) and the replicated study refers to the student’s experiment they conduct themselves.

If you’re not sure of the theory, model or effect that the original study is based on, find the original journal article and read the Introduction. If nothing is mentioned there, I would choose a different study.

How to Link the Theory to the Study

The rubric states that you”ll only get top marks for your Introduction if “(t)he theory or model upon which the student’s investigation is based is described and the link to the student’s investigation is explained.” It’s the second part I am going to focus on in this blog post because it’s the most ignored.

The rubric makes it difficult by stating “investigation” rather than study. It’s not sure what should be linked – the original or the replication. This is why it’s a good idea to do both.

Use the theory to explain the results of the original study 

Your introduction should begin with a detailed description of your background theory/model. After this it makes sense to describe the methods and results of the original study, even though it’s not mentioned in the rubric.

The first way to link your investigation to the theory/model is to use it to explain the results of the original study. Examples:

  • Use schema theory to explain why the title before people remembered more details in Bransford and Johnson,
  • Use dual processing model to explain why a high anchor is going to lead to a higher guess compared to a low anchor,
  • Use the facial feedback hypothesis to explain why people who fake a smile have a higher increase in mood,
  • etc.

This is the first way you can link your investigation to the study. Here’s an example taken from our IA exemplar in the Teacher Support Pack for the IA.

Notice how the study’s description stays focused by only including the relevant details and the results are explained using the background theory.

Explain how your aim is testing the theory

In your introduction you need to make sure “The aim of the investigation is stated.” Generally speaking, the aim of any experiment is to test the effect of an IV on a DV. I would recommend this is how you write your aim here. After you write the aim, you can also explain how this aim will test at least one specific claim of your background theory or model. If you’re writing about an effect, you could explain how the aim of your replicated study is to determine the existence of an effect.

For example, let’s say I was replicating a minimal group study and my background theory was social identity theory (you should not do this for you IA, btw). I could state: “The aim of our investigation is to see if identifying with an in-group will have an effect on in-group bias.” I could then go on to say, that “This aim is testing one of the central claims of social identity theory that prejudice and discrimination happens because people have a natural tendency to be biased towards their own in-groups.”

This is a second way my investigation is now linked to the theory.

Explain the relevance of your aim and theory

Another thing to include in your introduction is an explanation of the relevance of your aim. This can be done by explaining the possible real-life applications of findings from your study. You can use this as another way to link your investigation to the theory/model by explaining why testing this theory is relevant.

Here’s an example based on social cognitive theory and the bobo doll study (NB: this is another example you shouldn’t do for your IA, but it’s used for demonstration purposes only):

If you do one, two or perhaps all three of these things you’ll definitely impress your examiner. Make sure everything else is done in your Introduction (like operationalizing variables) and you’re off to a great start.

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