The dependence of perceived contrast on stimulus contrast of sinewave gratings was measured by the method of magnitude estimation. The resulting perceived contrast functions are well described by threshold-corrected power functions with exponents near 0.7. The exponents are insensitive to changes in mean luminance from 10-340 cd/m2 and to changes in spatial frequency from 0.25 to 12 c/deg. The exponents are also insensitive to a change in the range of grating contrasts from 1-2 log units. However, the distribution of contrast levels within the range produces small, but predictable, effects. Several factors are identified that may account for discrepancies in previous measurements of perceived contrast functions.
Bibliographical noteFunding Information:
~c~now~edge~ents-tWhea nk Dr DwightB urkhardat nd Dr Neal Viemeisterf or their helpful commentso n the manuscript.T his researchw as supported,i n part by a grantf rom the National Eye Institute( EY02857t)o G.E.L. and by grantst o the University of Minnesota,C enter for Researchin Human Learning,f rom the National Science Foundation( NSF/BNS-77-22075a)n d the National Institute for Child Health and Human Development (T36-HD-07151an d HD-01136t)o G.S.R.