Figure 5

Disk visibility is represented as the percentage of users noticing stimuli given for (a) a general approach (mean contrast), (b) a high contrast, (c) a medium contrast, and (d) a low contrast of disc color and background, given for three different frequencies of flickering: 1.5 Hz, 2 Hz, and 4 Hz and for three different angular distances: horizontal (46 deg), vertical (70 deg), and diagonal (80 deg).