Abstract
Visual texture on floors may facilitate safe mobility by providing information to pedestrians about surface slant and discontinuities. Often, ground plane texture is composed of fine detail and is beyond the acuity limit or below the contrast threshold of people with low vision. Consequently, we investigated whether a surface with large, high-contrast texture elements would enhance the detectability of steps and ramps for low-resolution viewing. Since the angular size of texture elements depends on viewing distance, we expected any benefits from texture to depend on both acuity and viewing distance. Subjects viewed a sidewalk interrupted by one of five possible targets: a single step up or down (7 inch height), a ramp up or down (7 inch change of height over 8 feet), or flat. Subjects reported which of the five targets was shown, and percent correct was computed from a block of trials. Viewing distance was 5, 10 or 20 feet from the target. Normally sighted subjects viewed the targets monocularly through goggles with two levels of blur having effective acuities of ∼20/135 (moderate blur) and ∼20/900 (severe blur). For the Texture group, the sidewalk was covered with a black and white, high contrast (0.87) checkerboard pattern with squares 12 inches on a side, surrounded by uniform mid-gray walls and flooring. Performance was compared with a group of subjects tested previously with a textureless gray sidewalk, walls, and floor (No-Texture group). With moderate blur, texture elements were visible and the Texture group outperformed the No-Texture group at all three distances. However, with severe blur, the groups performed comparably, with best performance at 5 feet. The results encourage us to consider the potential value of flooring with large texture elements for enhancing visual accessibility in public spaces.