Three studies were conducted to evaluate the effect of various mirror reflectivities on the opinions and performance of drivers in a variety of situations. One of the mirrors being evaluated employed a dual reflectivity principle, having a narrow band of low reflectivity (about 14%) against a higher reflectivity background (about 45%). The first study required subjects to detect the presence of a following car, and indicate which lane it was in. This was conducted as a laboratory study using movies of the car and roadway and simulating a twilight condition. Reaction times, error scores, and preferences favored mirrors of 36% reflectance or more. The banded mirror had comparable error performance to the other mirrors but significantly longer reaction times and poorer preference ratings. In the second study, conducted at night on the road, subjects were asked to rate interior and exterior mirrors for their visibility and glare reduction effectiveness. Only the 85% mirror was rated significantly higher than the banded mirror in visibility. The 4% and 14% reflectivities were rated significantly higher in reducing glare than most other mirrors. The differences were not significant, however, between the 14% and 14% banded mirrors. Thus, the banded mirror was about as effective as the 14% mirror in reducing glare yet gave better visibility to the rear. The final road study called for subjects to make passing maneuvers in front of an overtaking vehicle at what they considered to be the last safe moment. This study was conducted during the day and at night with the same subjects in each group. Results based on mean glance durations and frequencies and subject evaluations favored the 45% uniform and 14% banded mirror as compared to a 14% uniform mirror. One of the most significant findings of the study was that subjects did not allow enough time to pull out and pass at 15 mph closing speed. Almost half of the trials would have resulted in collisions at this relative speed.

  • Supplemental Notes:
    • Study sponsored by Harmon International Industries, Incorporated.
  • Corporate Authors:

    Highway Safety Research Institute

    Huron Parkway and Baxter Road
    Ann Arbor, MI  United States  48109
  • Authors:
    • Olson, P L
    • Jorgeson, C M
    • Mortimer, R G
  • Publication Date: 1974-4-17

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: 58 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00081237
  • Record Type: Publication
  • Source Agency: Highway Safety Research Institute
  • Report/Paper Numbers: UM-HSRI-HF-74-22 Final Rpt.
  • Contract Numbers: UM-320298
  • Files: TRIS
  • Created Date: Mar 26 1975 12:00AM