## 3 Materials and Methods
### Experimental Set-up  
We set up a proof-of-concept experiment with real users to get a hint of the effectiveness of the application (i.e., its ability to help users focus their attention on the reading task).  
A total of 10 male subjects and 10 female subjects were recruited from 6 th to 8 th grade in schools.  
Taking into account the level of education of the subjects, six excerpts from the novel \(I\)_Promessi Sposi (The Bethroted)_ by [PERSON] in its original Italian version were selected and named \"E1\", \"E2\",...\"E6\". Each excerpt was four pages long, text only and without figures.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Device** & **CPU** & **RAM Capacity** & **Frame Rate** \\ \hline Tablet & A12X, 8 cores, 2.48 GHz & 4 GB & 24 \\ Tablet & Kirin 659, 8 cores, 2.36 GHz & 3 GB & 15 \\ Raspberry Pi 3B+ & Cortex A53, 4 cores, 1.4 GHz & 1 GB & 10 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Tested devices and obtained frame rates.  
Figure 7: MICA characters support deictic visual cues.  
We set up 20 tablets (one for each subject) with a web-based e-book reader application that supported the MICA (see Figure 4). Each subject was initially left with the device and the e-reader application running on a different text for 10 min to familiarize with the application and the presence of the MICA interactive character. A briefing was also provided, presenting the trial as a challenge and advising the subjects that they should not be distracted by the character and that staring at the character would reduce their performance.  
Two different experimental conditions were devised. In the first condition (C1), a non-interactive animated character was shown on the screen that was graphically identical to the MICA character but unable to provide any feedback to the user. In the second condition (C2), the MICA character was shown and gave immediate feedback to the user. Immediate feedback, according to the definition in Section 3.2, was provided only after a given cumulative amount of distraction was detected.  
After the initial familiarization interval, all subjects were asked to read the six excerpts in sequence in condition C1. For this task, 13 min per excerpt (approximately 3 min per page) were given plus a 1-min stop between two subsequent excerpts. Once all subjects completed their tasks, the first reading session was closed, and a second session was planned after a 1-day pause.  
In the second reading session, all subjects were asked to read the six excerpts in sequence again but under condition C2. Again, 13 min per excerpt were given (approximately 3 min per page) plus a one-minute stop between two subsequent excerpts. Once all subjects completed their tasks, the second reading session was also closed, which also concluded the data gathering process.  
For each trial (that is, a user reading an excerpt), the following set of measures was collected:  
* The total reading time for the entire excerpt;
* The number of distraction events detected during the trial;
* The total reading time during which the user was distracted (i.e., the cumulative distraction time during the reading session).  
In this proof-of-concept experiment, we did not take into account the structure of the document. As a consequence, a distraction was detected only when the user's eye gaze moved away from the page being read, including when the fixation moved from the text page to the animated graphical character, which resided on a different screen area. Other types of distraction symptoms, such as an eye's gaze wandering on the page or moving back and forth or staring at a specific area for a long time, were not considered.