Pattern Glare Test
Participants viewed one of the grating patterns from the PGT (Wilkins et al., 1984). Because the online format precluded monitor calibration and validations of cycles per degree were not possible. Because it is high contrast and robust to various screen settings, we presented a medium spatial frequency image (horizontal square-wave grating at a Michelson contrast of ~0.7) for 5 seconds, based on Pattern 2 of Wilkins and Evans (2001) PGT ; see Figure 1. Participants were asked to fixate on the central fixation point embedded in the image. They were asked to endorse percepts via mouse click from the following options: pain/discomfort, shadowy shapes amongst the lines, shimmering of the lines, flickering, colors, blur, bending of the lines, nausea/dizziness, unease, other, and none of the following. Participants could select as many options as they wished.