Threshold sizes for accurate identification were determined for three different types of highway signs (text, icon, and modified icon) under two conditions of horizontal target motion. The two iconic versions were superior to the text version in nearly all cases, and this benefit of the pictorial format was even more pronounced in the higher-velocity condition. The advantage of the modified icon signs over the standard icon signs that had been determined in previous work was replicated here under the low-velocity condition but essentially disappeared under the higher-velocity condition. Sign-reading performance was found to be related to dynamic visual acuity under the two velocity conditions. Results are discussed in terms of the "low-pass format" for sign design suggested by previous researchers and in terms of the potential utility of dynamic acuity for driving setting.
Abstract