PERCLOS: A VALID PSYCHOPHYSIOLOGICAL MEASURE OF ALERTNESS AS ASSESSED BY PSYCHOMOTOR VIGILANCE

This Tech Brief summarizes an Intelligent Transportation System (ITS) study titled "Evaluation of Techniques for Ocular Measurement as an Index of Fatigue and as the Basis for Alertness Management." The study was funded in part by the Federal Highway Administration's (FHWA's) Office of Motor Carriers and managed by the National Highway Traffic Safety Administration (NHTSA). The project's goal was to evaluate the validity and reliability of several drowsiness-detection measures and technologies in a controlled laboratory setting, and to analyze the effects of alerting stimuli on drivers' alertness levels. Of the drowsiness-detection measures and technologies evaluated in this study, the measure referred to as "PERCLOS" was found to be the most reliable and valid determination of a driver's alertness level. PERCLOS is the percentage of eyelid closure over the pupil over time and reflects slow eyelid closures ("droops") rather than blinks. A PERCLOS drowsiness metric was established in a 1994 driving simulator study as the proportion of time in a minute that the eyes are at least 80% closed. FHWA and NHTSA consider PERCLOS to be among the most promising known real-time measures of alertness for in-vehicle drowsiness-detection systems. The results of this research support the development of a "first-ever" real-time drowsiness detection sensor that would measure the percentage of eyelid closure over the pupil, over time (i.e., PERCLOS).

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• Record URL:
  https://rosap.ntl.bts.gov/view/dot/14304
• Record URL:
  https://rosap.ntl.bts.gov/view/dot/113
• Corporate Authors:

  Federal Highway Administration

  Office of Motor Carrier Research and Standards, 1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Publication Date: 1998-10

Language

• English

Media Info

• Features: Figures; References; Tables;
• Pagination: 4 p.
• Serial:
  • Tech Brief
  • Publisher: Federal Motor Carrier Safety Administration

Subject/Index Terms

• TRT Terms: Alertness; Drivers; Drowsiness; Fatigue (Physiological condition); In vehicle sensors; Intelligent transportation systems; Truck drivers
• Subject Areas: Highways; Operations and Traffic Management; Safety and Human Factors; I83: Accidents and the Human Factor;

Filing Info

• Accession Number: 00760599
• Record Type: Publication
• Report/Paper Numbers: FHWA-MCRT-98-006
• Files: NTL, TRIS, USDOT
• Created Date: Mar 31 1999 12:00AM