CONTRAST SENSITIVITY OF PARTICIPANTS IN AUTOMOBILE HIGHLIGHT EXPERIMENTS

SINCE THE DETECTION OF LOW CONTRAST OBJECTS IS CONSIDERED TO BE A MAJOR TASK OF NIGHT DRIVING RELATING TO SAFETY, A PROGRAM HAS BEEN DEVELOPED TO MEASURE CONTRAST SENSITIVITY AT LIGHT LEVELS COMPARABLE TO THOSE PREVAILING ON ROADWAYS AT NIGHT. CONTRAST IS DETERMINED BY THE LUMINANCE DIFFERENCE BETWEEN THE ADAPTING BACKGROUND AND THE TARGET TO BE DETECTED. THE BASIC TECHNIQUE USED IS THE PSYCHO-PHYSICAL ONE IN WHICH PARTICIPANTS RESPOND TO A PRESENTED STIMULUS AND THE RESULTING BEHAVIOURAL EFFECT IS RECORDED IN A LABORATORY ENVIRONMENT. THE TASK IS THE DETECTION OF A TARGET WHICH IS BRIGHTER THAN ITS BACKGROUND AND SIMILAR IN DIFFICULTY TO THE DETECTION OF DARK HAZARD-LIKE OBJECTS WHILE NIGHT DRIVING. DRIVERS PARTICIPATING IN CONTROLLED HIGHWAY EXPERIMENTS DESIGNED TO EVALUATE EXISTING HEADLAMP SYSTEMS WERE TESTED FOR BRIGHTNESS DISCRIMINATION. CONTRAST SENSITIVITY IN A DETECTION TASK MAY BE RELATED TO ACUITY AS MEASURED IN A RECOGNITION TASK (REF. 3), ALTHOUGH CONTRAST SENSITIVITY AT LOW LUMINANCE LEVELS DOES NOT GENERALLY CORRELATE WITH ACUITY AT HIGH LUMINANCE LEVELS SUCH AS THOSE EMPLOYED IN A SNELLEN TEST. THE TECHNIQUE SELECTED TO MEASURE CONTRAST SENSITIVITY IS THE ONE DEVELOPED BY H.R. BLACKWELL (REF. 1). THE METHOD IS BASICALLY A FORCED-CHOICE TASK WHEREIN A PARTICIPANT MUST RESPOND TO EVERY POSSIBLE OCCURRENCE OF A TARGET PRESENTATION. THE TARGET SIZE, SHAPE AND POSITION ARE KNOWN. THE PARTICIPANT MUST INDICATE IN WHICH ONE OF 4 WELL DEFINED TEMPORAL INTERVALS THE RANDOMLY PRESENTED LUMINANCE INCREMENT HAS OCCURRED. AT LOW RELATIVE CONTRAST RATIOS, CORRECT SCORES MAY BE ATTRIBUTED TO CHANCE. IT IS IN THIS MANNER THAT THE EXTREMELY IMPORTANT MATTER OF DETECTION LEVEL IS DEFINED BY THE EXPERIMENT AND NOT BY THE PARTICIPANT AS IN A FREE-CHOICE TASK.

  • Supplemental Notes:
    • RPT NO LTR-ST. 600
  • Corporate Authors:

    Nat Aeronautical Establishment /Can

    /Nat Res Council
    ,   USA 
  • Authors:
    • HUCULAK, P
    • Blais, R
  • Publication Date: 1973-3-13

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 15 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00222314
  • Record Type: Publication
  • Source Agency: Highway Safety Research Institute
  • Files: TRIS
  • Created Date: Jul 31 1974 12:00AM