## 5 Materials and Methods
### Experimental Equipment  
The data were collected on a laptop in a Tecnalia meeting room throughout January 2020. The laptop was a MSI GS75 stealth i7 laptop and was located far enough away to avoid distractions caused by actions taken by the researcher. For the study, we employed Tobii Pro Lab (TPL) software version 1.130.24185, utilizing the integrated browser within the software to present the tests on a DELL e2310 23-inch monitor connected to a laptop. Eye movements of the participants were recorded with the Tobii X2-30 Eye Tracker, a discreet and standalone device designed for in-depth research on natural behavior. The eye-tracker, operating at a frequency of 30 Hz, was positioned at the base of a separate 17-inch monitor, which was used to monitor the participants' eye and head positions.  
Figure 3: Design of Item4 showing a screenshot of an e-mail written in Spanish. The letters A–I correspond to the iden-tifiers assigned to each defined area of interest.  
Figure 2: Design of Item32 showing a screenshot of a news article written in Spanish. The letters A–I correspond to the identifiers assigned to each defined area of interest.  
During tracking, the eye-tracker uses infrared illuminators to generate reflection patterns on the corneas of the participant's eyes. These reflection patterns, together with other visual data about the participant, are collected by image sensors. Sophisticated image processing algorithms identify relevant features, including the eyes and the corneal reflection patterns. Complex mathematics is used to calculate the 3D position of each eyeball and, finally, the gaze point (in other words, where the participant is looking). The timing and placement of mouse clicks were documented as part of the data collection.  
Six distinct projects were created within the TPL framework for the purposes of this research. Each project commenced with a self-evaluation, during which participants indicated their perceived level of competence. Each stimulus was linked to an item previously selected in the tests. All tests and items were displayed in the same order. We selected two types of stimuli according to the item formats included, as follows: (1) Web stimulus, to display webpages to participants during a recording. TPL opens the website's URL in the built-in Lab browser, and automatically registers all mouse clicks, keystrokes, and webpages accessed. (2) Screen recording stimulus, to register all mouse clicks, keystrokes, programs, and webpages accessed, i.e., all activity displayed on the screen from the beginning to the end of the stimulus. In particular, the 3 items selected for this study were recorded using a Web stimulus.  
For each stimulus, distinct AOIs and TOIs were established. The AOI is a concept used in TPL that allows the researcher to calculate quantitative eye movement measures. So, we drew a boundary encompassing the elements of the ET stimulus relevant to our study. We created AOIs in all the areas of the questions that we thought might attract their attention. TPL then calculates the metrics within the boundary over the time interval of interest. TOI is another TPL concept that provides a degree of analytical flexibility, allowing researchers to organize the recording data according to intervals of time during which meaningful behaviors and events take place. In simulations/image-based queries, we selected the intervals at which users viewed the image.  
In summary, the main goal of the scan-path analysis was to understand how participants interacted with different stimuli and tasks, and how their attention was distributed across different areas and times. This was achieved through the use of ET and the TPL analysis tool.