2.2.2. Experimental Protocol

The tests have been presented to a group of 95 participants (61 males and 34 females), with age of 29 ± 12 years (mean ± SD). All participants filled a form declaring their agreemen<sup>t</sup> to participate in this scientific test. All volunteers had no visual impairments (i.e., none of them wore glasses or contact lenses, all volunteers were checked for color blindness) and in general, were healthy with no apparent or declared mobility problems (e.g., use of walking aids). Since the sets of words were written in Italian, all the selected participants were native Italian speakers. The participants were recruited among the population visiting the "Maker Faire 2019" (The European edition, Rome, Italy).

Since the chair was equipped only with force sensors on the seat, the backrest was removed, so the chair was used like a stool in its use during the test. Each participant was invited to sit in a natural position, without crossing their legs. Participants were not informed about the scope of the test before conducting it, in order not to influence their behavior during its execution. Participants were briefly instructed about the tasks to be conducted, and further detailed instructions (i.e., "read the word on the slide" or "read the color of the words") were provided during the displaying of the words sets (i.e., at the beginning and at each phase transition of the test). The participants were asked to read aloud as quick as possible the words' meaning for the sets displayed in PHA and PHB, and the color of each word regardless of its meaning for the sets displayed in PHC. After the conclusion of the test, each participant was informed about the presence of the sensors under the seat and about the recorded data. Moreover, participants were informed that they were part of a scientific study, and everybody confirmed the given consensus to be part of the studied population. Nobody felt the presence of sensors during the test or a feeling di fferent than that of sitting on a normal stool. Recorded data were stored in a database, together with the personal information of the volunteers (i.e., age and gender), and associated to a code for each participant. A list matching the participant name and the code was encrypted and stored in a di fferent storage device from that of the database.
