Readability of Alphanumeric Characters Having Various Contrast Levels as a Function of Age and Illumination Mode

Readability data of alphanumeric characters that vary in figure-to- ground contrast ratio were obtained from 36 subjects; 12 subjects were placed in each of three age groups (20-25 yr, 40-45 yr, and 60-65 yr). Minimum illuminance required to identify all contrast combinations was determined at a vie...

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Bibliographic Details
Main Authors: Welsh, Kenneth W, Rasmussen, Paul G, Vaughan, John A
Format: Report
Language:English
Subjects:
AGING(PHYSIOLOGY)
ALPHANUMERIC DISPLAYS
Anatomy and Physiology
BACKGROUND
CHARTS
COLORS
CONTRAST
INCANDESCENT LAMPS
LPN-FAA-AM-D-77-PHY-93
LUMINANCE
READING
TARGET DISCRIMINATION
THRESHOLDS(PHYSIOLOGY)
VISUAL ACUITY
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Summary:Readability data of alphanumeric characters that vary in figure-to- ground contrast ratio were obtained from 36 subjects; 12 subjects were placed in each of three age groups (20-25 yr, 40-45 yr, and 60-65 yr). Minimum illuminance required to identify all contrast combinations was determined at a viewing distance of 40 cm (15.7 in) under dim white and red illumination. Subjects identified all characters while viewing through an artificial pupil (2.0mm) and, when required, while wearing a spectacle lens correction. Data indicate a significant difference in luminance values for successive changes in contrast ratio under both illumination modes. Under red illumination, threshold luminance values showed a significant trend with age for all five contrast levels. Under white illumination, significant trends were indicated for three of the five contrast levels. With reference to the younger group, individuals in the middle- aged and older groups required an average luminance increase of 18 and 63 percent respectively for equivalent readability scores under white illumination. Under red lighting, corresponding values were 18 and 58 percent.