title: Contrast detection and discrimination in young and older adults.
abstract: OBJECTIVE
  To determine if age differences in contrast detection thresholds extend to suprathreshold contrast discrimination.
  
  
  METHODS
  Psychophysical contrast detection and discrimination thresholds were determined in 56 adults ranging in age from 22 to 72 years. In experiment 1, thresholds were measured using a two-interval forced-choice procedure across a range of pedestal grating contrasts. In experiment 2, detection and discrimination thresholds were measured at two spatial frequencies and two luminance levels.
  
  
  RESULTS
  When normalized to the contrast detection threshold, contrast discrimination thresholds were similar in young and older adults. This result is akin to previous findings for clinical patients with contrast detection deficits. In addition, contrast discrimination in the elderly is independent of mean display luminance as has been found in young adults.
  
  
  CONCLUSIONS
  Normalized contrast discrimination functions have the same shape in young and older adults and show no change with a 4-fold reduction in luminance.
authors.affiliation: State College of Optometry, State University of New York, New York.
authors.forename: B L
authors.initials: BL
authors.lastname: Beard
authors.forename: D
authors.initials: D
authors.lastname: Yager
authors.forename: S
authors.initials: S
authors.lastname: Neufeld
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology*; D006801:Humans; D008027:Light; D008875:Middle Aged; D011597:Psychomotor Performance; D011601:Psychophysics / Q000379:methods; D012684:Sensory Thresholds / Q000502:physiology; D013028:Space Perception / Q000502:physiology