An evaluation of color selections to accommodate map users with color-vision impairments

An experiment shows that maps can be designed to accommodate the approximately 4 percent of the population with red-green color-vision impairments. The experiment used seven pairs of maps with seven different color schemes to determine the effects of color selection on the map-reading ability of people with impaired or normal color vision. One rendition in each pair had colors that were potentially confusing to people with red-green impairments; the other had colors selected specifically to accommodate this group. On the set with potentially confusing colors, people with red-green impairments were less accurate and took longer to respond than those with normal color vision. They were just as accurate as those with normal color vision on the set with accommodating colors but continued to have longer reaction times. Logit analysis of accuracy confirmed the interaction between vision group (normal, impaired) and rendition of the map (confusing, accommodating) and indicated that performance differed from one color scheme to another. An analysis of variance of reaction times on legend-matching questions yielded similar results for the same variables. A second part of the test asked participants to choose from each pair (confusing, accommodating) of the renditions the map that was easier or better to use. Those with red-green impairments overwhelmingly chose the accommodating renditions; those with normal color vision did not show a clear preference for one rendition over the other.