Conspicuity of Traffic Signs Assessed by Eye Tracking and Immediate Recall

Abstract

Traffic sign conspicuity was assessed with eye glance and immediate recall measures. Sign conspicuity is defined as the probability that the signs will be noticed. However, the measurement of being noticed is complex. Drivers’ glances to signs were recorded on a 34 mile drive. Recall was assessed by requesting sign identification immediately after selected signs were passed. Only about half of all signs were recalled just 2 s after they were passed. About 20 percent of speed limit signs received glances; however drivers were aware of the posted speed limit about 80 percent of the time. Drivers may glance at signs, yet fail to identify them and may correctly identify signs in the absence of a glance. Conspicuity measures that rely solely on either glance or recall are not adequate for evaluating the attention getting qualities of traffic signs.