Twelve subjects (20-37 years old) were tested in the laboratory and 11 out of these were also tested in a car in the field, first under a no alcohol condition and then under an alcohol condition (approximately 0.10% BAC). In the laboratory the subjects' simple and choice reaction times for two uncertainty modes were measured and their information processing rates were determined. In the field the subjects' driving skill for driving through a gap (soft obstacles, 20 inches clearance) at 20 miles/hour, their static visual gap (car and Post) judgement of abilities and their gap risk acceptance decisions for a 50 feet viewing distance (using psychophysical experimental methods) were measured. Based upon the driving skill measure (standard deviation of centerline deviations in the gap), the mean of the psychometric visual gap perception function and the mean of the psychometric gap risk acceptance function the Safety Distance and the Driver Safety Index (DSI), developed by Zwahlen were obtained. A conceptual model illustrating a phypothetical localized system failure, developed by Blumenthal (1968), has been modified in such a way that the system demands on the driver-vehicle system are represented in terms of choice reaction times, while the driver performance at any point in time is represented by two choice reaction time probability distributions, one representing the sober condition, the other representing the alcohol condition. This modified system model is used to demonstrate that the combined time increase in mean performance and performance variability under the influence of alcohol provide a much better explanation for the higher small decrements in mean performance. /Author/

  • Supplemental Notes:
    • This paper is based upon a presentation given at the 18th Annual Meeting of the Human Factors Society, Huntsville, Alabama, October 15-17, 1974.
  • Corporate Authors:

    Elsevier Publishing Company, Incorporated

    52 Vanderbilt Avenue
    New York, NY  United States  10017
  • Authors:
    • Zwahlen, H T
  • Publication Date: 1976-7

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Filing Info

  • Accession Number: 00148752
  • Record Type: Publication
  • Source Agency: National Safety Council
  • Files: TRIS
  • Created Date: May 11 1977 12:00AM