Visual Detection of Detectable Warning Materials by Pedestrians with Visual Impairments - Final Report

2.11 Perceived Color of Detectable Warnings

The ability of people with visual impairments to correctly recognize the color of detectable warnings has important implications for both conspicuity and the potential for detectable warning color standardization. One possible reason to standardize detectable warning color is to have detectable warning color impart a specific meaning in the same way that the colors of various roadside signs have particular meanings. However, if color perception for pedestrians with visual impairments is not consistent across individuals or not stable among individuals or across lighting conditions, the “message” intended by the standardized color of a detectable warning may not be received by the intended recipients.

Participants were asked to describe the color of each detectable warning that they saw. These descriptions were made at a distance of 2.44 m (8 ft) from the detectable warning. Numerous color descriptions were given for each detectable warning and these descriptions often seemed to be influenced by the color of the sidewalk. For instance, the dark gray detectable warning was much more likely to be described as “black” on the white concrete sidewalk than it was on any other sidewalk. Presumably, this was because the high contrast provided by the white sidewalk made the detectable warning look darker by comparison. In most cases, participants provided color descriptions that were consistent with each other and with the visually unimpaired experimenters’ perceptions. However, for every detectable warning there were several unusual descriptions. The participants whose vision was most impaired were often the most likely to use color names not used by other participants. The complete set of color descriptions given by participants for each detectable warning and side walk combination is presented in Appendix F.