Hi Sanghee,
The EyeTracker element tracks gazes on the elements that you’ve added to it. Since the elements you’ve added to it at the four quadrant Canvas elements, and since each is 50vw*50vh, those are the boundaries of the corresponding elements. If the tracker estimates a gaze to fall within the left 50% of the width of the screen and 50% of the height of the screen, then it will report 1 for _TopLeft, indeed
Jeremy