Citation

Sivak M, Flannagan MJ, Miyokawa T, Traube EC. Transp. Hum. Fact. 2000; 2(2): 135-150.

Affiliation

University of Michigan Transportation Research Institute

Copyright

(Copyright © 2000, Informa - Taylor and Francis Group)

DOI

10.1207/STHF0202_04

PMID

unavailable

Abstract

In this field study we investigated the efficiency of color coding for peripheral identification of vehicle signals. Specifically, the study dealt with identification of stimuli as yellow or red when presented at intensities corresponding to typical turn-signal lamps and side-marker lamps. Turn-signal lamps were studied both during bright, sunny conditions and at night, whereas side-marker lamps were studied at night only. We used two yellow stimuli and two red stimuli. For each color category, one stimulus was relatively far from the contrasting color category and the other stimulus was relatively near. Four viewing angles were used: 0°, 10°, 20°, and 30° from visual fixation. We tested 28 participants ranging in age from 21 to 78 years. Nighttime identification of colors was perfect at all viewing angles for stimuli representing turn-signal lamps. On the other hand, strong effects of viewing angle were found for turn-signals in the daytime and for side-marker lamps at night. Although in these 2 conditions performance deteriorated for stimuli in both color categories, it did so more for the red stimuli. This finding is consistent with the previously reported finding that peripherally presented red stimuli often appear yellow. The findings imply that coding signals yellow and red is not sufficient for their peripheral identification under the 2 most difficult conditions tested (turn signals during bright daytime and side-marker lamps during nighttime). To the extent that peripheral discriminability is important in actual driving, efficient signaling should rely on other coding parameters (e.g., intensity, and flashing vs. steady burning).