Abstract
Visual accessibility is the use of vision to travel efficiently and safely through an environment, to perceive the spatial layout of the environment, and to update one's location in the layout. The present study extends the findings of Legge et al. (J. Vis., 2010) who described the effects of lighting, geometry, and surface properties on the recognition of ramps and steps by stationary subjects. Since locomotion can provide information about surface depth and orientation, the current investigation explores whether locomotion toward a ramp or step might enhance recognition accuracy. Twelve normally sighted young adults viewed a sidewalk interrupted by one of five possible targets: a single step up or down, a ramp up or down, or flat. Subjects reported which of the five targets was shown, and percent correct was computed from a block of trials. Subjects viewed the targets monocularly through goggles with an effective acuity of ∼20/900 (severe blur). They made target recognition judgments from distances of 5 ft or 10 ft either after stationary viewing or after walking 10 ft to the same viewing locations. In the texture condition, the sidewalk was covered with a high-contrast checkerboard pattern, surrounded by black walls and flooring. In the plain condition, the sidewalk was uniform gray. Subjects recognized ramps and steps significantly more accurately in walking trials (64%) than in stationary trials (58%), p < .05. Consistent with our previous results, ramps and steps were more accurately recognized overall with the plain floor (65%) than the textured floor (56%), but this difference was not statistically significant for the walking trials. We conclude that locomotion enhances the visibility of ramps and steps, and may enhance visual accessibility for people with low vision. Locomotion may also partially negate the deleterious effects of misleading floor-texture features.