OPTIMAL FLASH RATE AND DUTY CYCLE FOR FLASHING VISUAL INDICATORS

THIS EXPERIMENT EXAMINED THE ABILITY OF OBSERVERS TO DETERMINE, AS QUICKLY AS POSSIBLE, WHETHER A VISUAL INDICATOR WAS STEADILY ON OR FLASHING. SIXFLASH RATES (PERIODS) WERE COMBINED FACTORIALLY WITH THREE DUTY CYCLES (ON-OFF RATIOS) TO DEFINE 18 "TYPES" OF INTERMITTENT SIGNALS. EXPERIMENTAL SESSIONS WERE DIVIDED INTO SIX RUNS OF 100 TRIALS, EACH RUN UTILIZING ONE OF THE SIX FLASH RATES. ON ANY GIVEN TRIAL IN A RUN, THE PROBABILITY OF A STEADY SIGNAL OCCURRING WAS 0.5 AND THE PROBABILITY OF A FLASHING SIGNAL OCCURRING WAS 0.5. A DIFFERENT DUTY CYCLE WAS EMPLOYED DAILY FOR EACH EXPERIMENTAL SESSION. IN ALL, 400 TRIALS WERE DEVOTED TO EACH OF THE FLASH RATES AT EACH DUTY CYCLE. ACCURACY AND LATENCY OF RESPONSE WERE THE DEPENDENT VARIABLES OF INTEREST. THE RESULTS SHOW THAT THE OBSERVERS VIEW THE LIGHT FOR AN INTERVAL OF TIME APPROPRIATE TO THE EXPECTED FLASH RATE AND DUTY CYCLE; WHETHER THEY JUDGE THE LIGHT TO BE STEADY OR INTERMITTENT DEPENDS UPON WHETHER THE LIGHT IS EXTINGUISHED DURING THE PREDETERMINED WAITING PERIOD. ADOPTION OF THIS TEMPORAL CRITERION DELAYS RESPONDING IN COMPARISON TO THOSE TASKS INVOLVING RESPONSES TO LIGHT ONSET. THE DECISION OR RESPONSE CRITERIA HELD BY THE OBSERVERS ARE ALSO SENSITIVE TO THE PARAMETERS OF THE FLASHING LIGHT: OBSERVERS BECOME INCREASINGLY WILLING TO CALL A FLASHING LIGHT "STEADY" AS FLASH DURATION INCREASES. /AUTHOR/

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/oclc/1329271
• Corporate Authors:

  Human Factors Society

  Johns Hopkins University Press
  Baltimore, MD  United States  21218
• Authors:
  • MARKOWITZ, J
• Publication Date: 1971-10

Language

• English

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 427-33
• Serial:
  • Human Factors
  • Volume: 13
  • Issue Number: 5
  • Publisher: Sage Publications, Incorporated
  • ISSN: 0018-7208
  • EISSN: 1547-8181
  • Serial URL: http://hfs.sagepub.com/

Subject/Index Terms

• TRT Terms: Flashing; Flashing traffic signals; Light; Perception; Testing
• Uncontrolled Terms: Observation
• Subject Areas: Highways; Safety and Human Factors;

Filing Info

• Accession Number: 00222461
• Record Type: Publication
• Source Agency: Transport and Road Research Laboratory (TRRL)
• Report/Paper Numbers: HS-011 230
• Files: TRIS
• Created Date: Jun 19 1973 12:00AM