SOME PSYCHOPHYSICAL TESTS OF THE CONSPICUITIES OF EMERGENCY VEHICLE WARNING LIGHTS

• NCJ Number: 59302
• Author(s): G L HOWETT
• Date Published: 1979
• Length: 27 pages
• Sponsoring Agency: US Dept of Justice; US Dept of Justice NIJ Pub
• Corporate Author: US Dept of Commerce
• Sale Source: Superintendent of Documents, GPO; US Dept of Commerce; National Institute of Justice/
• Language: English
• Country: United States of America
• Note: LIMITED NUMBER OF COPIES AVAILABLE FROM NBS

Annotation

PART OF A PILOT STUDY OF THE ATTENTION-ATTRACTING POWERS OF SOME COMMERCIAL WARNING LIGHTS FOR EMERGENCY VEHICLES, THIS REPORT SUMMARIZES RESULTS FROM CONSPICUITY STUDIES AND PSYCHOPHYSICAL TESTS.

Abstract

THE REPORT RESULTS FROM A PROJECT ON EMERGENCY VEHICLE LIGHTS, WHICH INCLUDED THE PHYSICAL MEASUREMENT (PHOTOMETRY) OF THE INTENSITIES OF SOME LIGHTS, PSYCHOPHYSICAL (PERCEPTUAL) TESTS OF LIGHTS FOR CONSPICUITY, AND SEVERAL REPORTS. THE MAIN EXPERIMENT USED A NOVEL TECHNIQUE OF CONSPICUITY MATCHING. EACH OBSERVER VIEWED TWO FLASHING LIGHTS PERIPHERALLY, ONE LOCATED 20 DEGREES TO THE LEFT OF THE FIXATION POINT, AND THE OTHER 20 DEGREES TO THE RIGHT. ONE OF THE TWO LIGHTS WAS ALWAYS A REFERENCE LIGHT WHOSE INTENSITY COULD BE ADJUSTED BY THE OBSERVER UNTIL THE TWO LIGHTS APPEARED EQUALLY CONSPICUOUS. ALL THE LIGHTS WERE RANKED ON A SINGLE SCALE OF CONSPICUITY, BASED ON THE ADJUSTABLE-LIGHT INTENSITIES. THERE WAS A GOOD CORRELATION BETWEEN THESE RANKS AND THE MEASURED EFFECTIVE INTENSITIES OF LIGHTS. ANOTHER, VERY BRIEF PILOT EXPERIMENT RANKED SOME OF THE LIGHTS BY THE NUMBER OF DEGREES INTO THE LEFT SIDE OF THE VISUAL FIELD THE FLASHES COULD BE SEEN. THIS DISAPPEARANCE-ANGLE ALSO CORRELATED WELL WITH CONSPICUITY RANK. SUGGESTIONS FOR FUTURE WORK IN THIS FIELD ARE PROVIDED, ALONG WITH DISCUSSION OF SOME OF THE PROBLEMS ENCOUNTERED IN THE PILOT STUDY. REFERENCES AND TABULAR AND GRAPHIC DATA ARE ALSO PROVIDED. THE TEXT OF THE INSTRUCTIONS PROVIDED OBSERVERS IS INCLUDED IN AN APPENDIX.