*3.3. Participants and Apparatus*

This study was approved by the Institutional Review Board (IRB) of the University's Institutional Bioethics Committee for the purpose of the eye-tracking experiment and survey. Participants were then recruited for the experiment. Participants had to have no vision problems, but those who wore glasses could participate. Due to the characteristics of the five sites mainly used by young people, participants in their 20s and 30s conducted experiments in March and April 2020. At the time the experiment was conducted, it was difficult to recruit external participants due to COVID-19. So, the recruitment of test subjects was mainly conducted within urban engineering students and experts who work in the same field, and the rest from the general public. Finally, a total of 41 people, including 26 majors, 15 of which were non-Communists, participated in the eye-tracking experiment and survey.

The eye-tracker device used was the GP3 HD Eye Tracker, from Gagepoint. The device is a fixed eye-tracker capable of measuring eyeball movement at 150 Hz per second. After the eye-tracker was installed on a 24-inch monitor, the distance between the participant and the monitor was set at 40–60 cm. Before the experiment, a calibration task was performed to properly fix the eyes of the participants to the camera of the eye tracker (Figure 1). Calibration is to adjust the distance and height between the eye and the eyetracker so that the eye-tracker recognizes the eye of the participant. Figure 1 shows that the eye-tracker recognizes the participant's pupils and appears in green. The next step in viewpoint adjustment is to test whether the eye tracker properly recognizes the participant's pupil. The test is a method of checking whether the green cursor moves exactly to the participant's viewing position by looking at the screen with 11 circles drawn on the monitor and moving their gaze (Figure 2). If the cursor moves differently from the participant's gaze, the viewpoint is adjusted again and tested.

**Figure 1.** Calibration Processing.

**Figure 2.** Eye movement testing.

Before showing the picture, a situation is assumed where the experimenter visits the commercial street in the picture and walks the streets and looks around freely. Participants looked at the experimental photos for 10 s per photo and conducted eye-tracking tests. After the eye-tracking experiment was over, they filled out a questionnaire for the photos. The total required time for this survey including the eye-tracking and questionnaire took 30–40 min.
