Interest areas (IAs), alternatively referred to as Areas of Interest (AoIs), are regions in the display that contain something that we are interested in. We use IAs to determine if, when, and how long participants examined interesting parts of the stimuli.
We don’t always need IAs for our studies. Many analyses, such as global measures, make no use of IAs (a point that we will return to later).
There are a number of different ways to implement your own interest areas in experiment builder:
- By hand
- Using a datasource
- Auto-segment function
- Custom code
- External custom code
- Getting creative
We’ll talk about each of these in turn next.
1. By hand
If you really need to, you can create interest areas by hand. This should be done with extreme caution since it is a lengthy process and will be prone to human error (even if you’re really, really careful).
To make interest areas by hand, first, run your study without them. That will then give you a set of trials containing an image and no interest areas. Next, open up the recorded data in Data Viewer. You can then draw them in manually, using the functions to insert interest areas, as shown in the animation below.
Once you have completed your interest areas for that particular trial, click the Save Interest Area set to Disk button, highlighted below. Save the file with a “.ias” extension. You now have an interest area for that trial!
What do you do next? Here are the steps:
- Return to Experiment Builder.
- Next, you open up the Library Manager that you used to import that images in the previous sessions. Select the Interest Areas tab and import your interest area text file(s) that you have created.
- Finally, you tell the trial itself to point to the interest area column of the datasource.
The last of these steps is shown below (since you’ve seen how to import files into the library in the previous sessions).
When you run the study again, it will now correctly load the interest area files.
2. Using a datasource
An alternative option is that you can point your interest areas to values in a datasource. Let’s take a look at the steps.
First, open up Experiment Builder. Next, open up your trial where you want the interest area to be. Then, draw an interest area as per the animation below.
But what if you want the interest area to be in a different place in each trial? Well, go back to your datasource. Add a new column, one called IA_X and another called IA_Y. These specify the x- and y-locations of your interest area for that trial. Note that computers start their co-ordinates with 0,0 at the top left of the screen. Finally, all you need to do is point your interest area’s location to the columns in the datasource, as shown below. The interest area will then dynamically change each trial depending on what your datasource says.
3. Auto-segment function
If you are using text components in Experiment Builder, Data Viewer will automatically generate interest areas around each word. However, if you are a reading researcher, you’ll need to increase the height of these interest areas (as you typically want the interest area to be taller than the word). You’ll also need to use some of the steps outlined in part (1) to move the interest areas around a bit. Reading researchers start the interest area for a given word in the space before a word, and Data Viewer doesn’t, so you’ll need to move the automatically-generated interest areas around a bit by hand.
4. Custom code
You can also use Experiment Builder’s python custom coding – something we won’t cover here – to control the location of interest areas.
5. External custom code
If you have drawn your images using software from elsewhere, you should also be able to use this same software to save interest area files for you programmatically. This is preferential since it will save a considerable amount of time and be more accurate and consistent than hand-drawing of interest areas.
6. Getting creative
Every experiment is different – often you may need to throw some part of all the above in order to get your interest areas to work properly. Good luck!