Abstract

Subjects estimated the perceived contrast of 2°-diameter sine-wave grating patches for spatial frequencies of 2, 4, 8, and 16 cycles/deg, at eccentricities from 0° to 40° and contrasts up to 0.8. The data were well fitted in all cases by power functions of contrast minus threshold, with exponents of the order of 0.5 implying similar mechanisms in both fovea and periphery. The data also demonstrate that, at high physical contrast, the visual system is generally driven toward an operating state in which two stimuli of equal physical contrast have equal perceived contrast even if the thresholds are quite different. As a consequence, peripheral perceived contrasts produced by high physical contrasts show almost no change with eccentricity, whereas thresholds increase by at least an order of magnitude. This implies that mechanisms mediating threshold detection and suprathreshold perception may be different.

© 1985 Optical Society of America

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References

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  1. A. Watanabe, T. Mori, S. Nagata, K. Hiwatashi, “Spatial sine-wave responses of the human visual system,” Vision Res. 8, 1245–1263 (1968).
    [CrossRef] [PubMed]
  2. C. Blakemore, J. P. J. Muncey, R. M. Ridley, “Stimulus specificity in the human visual system,” Vision Res. 13, 195–1931 (1973).
    [CrossRef]
  3. M. A. Georgeson, G. D. Sullivan, “Contrast constancy: deblurring in human vision by spatial frequency channels,” J. Physiol. (London) 252, 627–656 (1975).
  4. D. O. Bowker, “Suprathreshold spatiotemporal response characteristics of the human visual system,” J. Opt. Soc. Am. 73, 426–440 (1983).
    [CrossRef]
  5. G. E. Legge, “A power law for contrast discrimination,” Vision Res. 21, 457–467 (1981).
    [CrossRef] [PubMed]
  6. G. E. Legge, J. M. Foley, “Contrast masking in human vision,” J. Opt. Soc. Am. 70, 1458–1471 (1980).
    [CrossRef] [PubMed]
  7. W. H. Swanson, H. R. Wilson, S. C. Giese, “Contrast matching data predicted from contrast increment thresholds,” Vision Res. 24, 63–75 (1984).
    [CrossRef] [PubMed]
  8. S. S. Stevens, “The direct estimation of sensory magnitudes—loudness,” Am. J. Psychol. 69, 1–25 (1956).
    [CrossRef] [PubMed]
  9. O. Franzen, M. Berkley, “Apparent contrast as a function of modulation depth and spatial frequency: a comparison between perceptual and electrophysiological measures,” Vision Res. 15, 655–660 (1975).
    [CrossRef] [PubMed]
  10. J. R. Hamerly, R. F. Quick, T. A. Reichert, “A study of grating contrast judgment,” Vision Res. 17, 201–207 (1977).
    [CrossRef] [PubMed]
  11. M. W. Cannon, “Contrast sensation: a linear function of stimulus contrast,” Vision Res. 19, 1405–1452 (1979).
    [CrossRef]
  12. J. Gottesman, G. S. Rubin, G. E. Legge, “A power law for perceived contrast in human vision,” Vision Res. 21, 791–799 (1981).
    [CrossRef] [PubMed]
  13. M. W. Cannon, “A study of stimulus range effects in free modulus magnitude estimation of contrast,” Vision Res. 24, 1049–1055 (1984).
    [CrossRef] [PubMed]
  14. M. W. Cannon, “Range effects in magnitude estimation of contrast,” Invest. Ophthalmol. Vis. Sci. Suppl. 25, 296 (1984).
  15. R. F. Hess, A. Bradley, “Contrast perception above threshold is only minimally impaired in human amblyopia,” Nature 287, 463–464 (1980).
    [CrossRef] [PubMed]
  16. D. S. Loshin, D. M. Levi, “Suprathreshold contrast perception in functional amblyopia,” Doc. Ophthalmol. 55, 213–236 (1983).
    [CrossRef] [PubMed]
  17. J. C. Stevens, S. S. Stevens, “Brightness function: effects of adaptation,” J. Opt. Soc. Am. 53, 375–385 (1963).
    [CrossRef] [PubMed]
  18. S. Takahashi, Y. Ejima, “Dependence of apparent contrast of a sinusoidal grating on stimulus size,” J. Opt. Soc. Am. A 12, 1197–1201 (1984).
    [CrossRef]
  19. P. M. Daniel, D. Witteridge, “The representation of the visual field in the cerebral cortex in monkey,” J. Physiol. 186, 558–578 (1961).
  20. D. H. Hubel, T. N. Wiesel, “Uniformity of monkey striate cortex. A parallel relationship between field size, scatter, and magnification factor,” J. Comp. Neurol. 158, 295–306 (1974).
    [CrossRef] [PubMed]
  21. C. Guld, A. Bertulis, “Representation of fovea in the striate cortex of vervet monkey, Cercopithecus aethiops pygerythrus,” Vision Res. 16, 629–631 (1976).
    [CrossRef] [PubMed]
  22. B. M. Dow, A. Z. Synder, R. B. Vautin, R. Bauer, “Magnification factor and receptive field size in foveal striate cortex of the monkey,” Exp. Brain Res. 44, 213–228 (1981).
    [CrossRef] [PubMed]
  23. V. Virsu, J. Rovamo, “Visual resolution, contrast sensitivity and the cortical magnification factor,” Exp. Brain Res. 37, 475–494 (1979).
    [CrossRef]
  24. J. Rovamo, V. Virsu, “An estimation and application of the human cortical magnification factor,” Exp. Brain Res. 37, 495–510 (1979).
    [CrossRef] [PubMed]

1984 (4)

W. H. Swanson, H. R. Wilson, S. C. Giese, “Contrast matching data predicted from contrast increment thresholds,” Vision Res. 24, 63–75 (1984).
[CrossRef] [PubMed]

M. W. Cannon, “A study of stimulus range effects in free modulus magnitude estimation of contrast,” Vision Res. 24, 1049–1055 (1984).
[CrossRef] [PubMed]

M. W. Cannon, “Range effects in magnitude estimation of contrast,” Invest. Ophthalmol. Vis. Sci. Suppl. 25, 296 (1984).

S. Takahashi, Y. Ejima, “Dependence of apparent contrast of a sinusoidal grating on stimulus size,” J. Opt. Soc. Am. A 12, 1197–1201 (1984).
[CrossRef]

1983 (2)

D. S. Loshin, D. M. Levi, “Suprathreshold contrast perception in functional amblyopia,” Doc. Ophthalmol. 55, 213–236 (1983).
[CrossRef] [PubMed]

D. O. Bowker, “Suprathreshold spatiotemporal response characteristics of the human visual system,” J. Opt. Soc. Am. 73, 426–440 (1983).
[CrossRef]

1981 (3)

G. E. Legge, “A power law for contrast discrimination,” Vision Res. 21, 457–467 (1981).
[CrossRef] [PubMed]

J. Gottesman, G. S. Rubin, G. E. Legge, “A power law for perceived contrast in human vision,” Vision Res. 21, 791–799 (1981).
[CrossRef] [PubMed]

B. M. Dow, A. Z. Synder, R. B. Vautin, R. Bauer, “Magnification factor and receptive field size in foveal striate cortex of the monkey,” Exp. Brain Res. 44, 213–228 (1981).
[CrossRef] [PubMed]

1980 (2)

G. E. Legge, J. M. Foley, “Contrast masking in human vision,” J. Opt. Soc. Am. 70, 1458–1471 (1980).
[CrossRef] [PubMed]

R. F. Hess, A. Bradley, “Contrast perception above threshold is only minimally impaired in human amblyopia,” Nature 287, 463–464 (1980).
[CrossRef] [PubMed]

1979 (3)

M. W. Cannon, “Contrast sensation: a linear function of stimulus contrast,” Vision Res. 19, 1405–1452 (1979).
[CrossRef]

V. Virsu, J. Rovamo, “Visual resolution, contrast sensitivity and the cortical magnification factor,” Exp. Brain Res. 37, 475–494 (1979).
[CrossRef]

J. Rovamo, V. Virsu, “An estimation and application of the human cortical magnification factor,” Exp. Brain Res. 37, 495–510 (1979).
[CrossRef] [PubMed]

1977 (1)

J. R. Hamerly, R. F. Quick, T. A. Reichert, “A study of grating contrast judgment,” Vision Res. 17, 201–207 (1977).
[CrossRef] [PubMed]

1976 (1)

C. Guld, A. Bertulis, “Representation of fovea in the striate cortex of vervet monkey, Cercopithecus aethiops pygerythrus,” Vision Res. 16, 629–631 (1976).
[CrossRef] [PubMed]

1975 (2)

M. A. Georgeson, G. D. Sullivan, “Contrast constancy: deblurring in human vision by spatial frequency channels,” J. Physiol. (London) 252, 627–656 (1975).

O. Franzen, M. Berkley, “Apparent contrast as a function of modulation depth and spatial frequency: a comparison between perceptual and electrophysiological measures,” Vision Res. 15, 655–660 (1975).
[CrossRef] [PubMed]

1974 (1)

D. H. Hubel, T. N. Wiesel, “Uniformity of monkey striate cortex. A parallel relationship between field size, scatter, and magnification factor,” J. Comp. Neurol. 158, 295–306 (1974).
[CrossRef] [PubMed]

1973 (1)

C. Blakemore, J. P. J. Muncey, R. M. Ridley, “Stimulus specificity in the human visual system,” Vision Res. 13, 195–1931 (1973).
[CrossRef]

1968 (1)

A. Watanabe, T. Mori, S. Nagata, K. Hiwatashi, “Spatial sine-wave responses of the human visual system,” Vision Res. 8, 1245–1263 (1968).
[CrossRef] [PubMed]

1963 (1)

1961 (1)

P. M. Daniel, D. Witteridge, “The representation of the visual field in the cerebral cortex in monkey,” J. Physiol. 186, 558–578 (1961).

1956 (1)

S. S. Stevens, “The direct estimation of sensory magnitudes—loudness,” Am. J. Psychol. 69, 1–25 (1956).
[CrossRef] [PubMed]

Bauer, R.

B. M. Dow, A. Z. Synder, R. B. Vautin, R. Bauer, “Magnification factor and receptive field size in foveal striate cortex of the monkey,” Exp. Brain Res. 44, 213–228 (1981).
[CrossRef] [PubMed]

Berkley, M.

O. Franzen, M. Berkley, “Apparent contrast as a function of modulation depth and spatial frequency: a comparison between perceptual and electrophysiological measures,” Vision Res. 15, 655–660 (1975).
[CrossRef] [PubMed]

Bertulis, A.

C. Guld, A. Bertulis, “Representation of fovea in the striate cortex of vervet monkey, Cercopithecus aethiops pygerythrus,” Vision Res. 16, 629–631 (1976).
[CrossRef] [PubMed]

Blakemore, C.

C. Blakemore, J. P. J. Muncey, R. M. Ridley, “Stimulus specificity in the human visual system,” Vision Res. 13, 195–1931 (1973).
[CrossRef]

Bowker, D. O.

D. O. Bowker, “Suprathreshold spatiotemporal response characteristics of the human visual system,” J. Opt. Soc. Am. 73, 426–440 (1983).
[CrossRef]

Bradley, A.

R. F. Hess, A. Bradley, “Contrast perception above threshold is only minimally impaired in human amblyopia,” Nature 287, 463–464 (1980).
[CrossRef] [PubMed]

Cannon, M. W.

M. W. Cannon, “A study of stimulus range effects in free modulus magnitude estimation of contrast,” Vision Res. 24, 1049–1055 (1984).
[CrossRef] [PubMed]

M. W. Cannon, “Range effects in magnitude estimation of contrast,” Invest. Ophthalmol. Vis. Sci. Suppl. 25, 296 (1984).

M. W. Cannon, “Contrast sensation: a linear function of stimulus contrast,” Vision Res. 19, 1405–1452 (1979).
[CrossRef]

Daniel, P. M.

P. M. Daniel, D. Witteridge, “The representation of the visual field in the cerebral cortex in monkey,” J. Physiol. 186, 558–578 (1961).

Dow, B. M.

B. M. Dow, A. Z. Synder, R. B. Vautin, R. Bauer, “Magnification factor and receptive field size in foveal striate cortex of the monkey,” Exp. Brain Res. 44, 213–228 (1981).
[CrossRef] [PubMed]

Ejima, Y.

S. Takahashi, Y. Ejima, “Dependence of apparent contrast of a sinusoidal grating on stimulus size,” J. Opt. Soc. Am. A 12, 1197–1201 (1984).
[CrossRef]

Foley, J. M.

Franzen, O.

O. Franzen, M. Berkley, “Apparent contrast as a function of modulation depth and spatial frequency: a comparison between perceptual and electrophysiological measures,” Vision Res. 15, 655–660 (1975).
[CrossRef] [PubMed]

Georgeson, M. A.

M. A. Georgeson, G. D. Sullivan, “Contrast constancy: deblurring in human vision by spatial frequency channels,” J. Physiol. (London) 252, 627–656 (1975).

Giese, S. C.

W. H. Swanson, H. R. Wilson, S. C. Giese, “Contrast matching data predicted from contrast increment thresholds,” Vision Res. 24, 63–75 (1984).
[CrossRef] [PubMed]

Gottesman, J.

J. Gottesman, G. S. Rubin, G. E. Legge, “A power law for perceived contrast in human vision,” Vision Res. 21, 791–799 (1981).
[CrossRef] [PubMed]

Guld, C.

C. Guld, A. Bertulis, “Representation of fovea in the striate cortex of vervet monkey, Cercopithecus aethiops pygerythrus,” Vision Res. 16, 629–631 (1976).
[CrossRef] [PubMed]

Hamerly, J. R.

J. R. Hamerly, R. F. Quick, T. A. Reichert, “A study of grating contrast judgment,” Vision Res. 17, 201–207 (1977).
[CrossRef] [PubMed]

Hess, R. F.

R. F. Hess, A. Bradley, “Contrast perception above threshold is only minimally impaired in human amblyopia,” Nature 287, 463–464 (1980).
[CrossRef] [PubMed]

Hiwatashi, K.

A. Watanabe, T. Mori, S. Nagata, K. Hiwatashi, “Spatial sine-wave responses of the human visual system,” Vision Res. 8, 1245–1263 (1968).
[CrossRef] [PubMed]

Hubel, D. H.

D. H. Hubel, T. N. Wiesel, “Uniformity of monkey striate cortex. A parallel relationship between field size, scatter, and magnification factor,” J. Comp. Neurol. 158, 295–306 (1974).
[CrossRef] [PubMed]

Legge, G. E.

G. E. Legge, “A power law for contrast discrimination,” Vision Res. 21, 457–467 (1981).
[CrossRef] [PubMed]

J. Gottesman, G. S. Rubin, G. E. Legge, “A power law for perceived contrast in human vision,” Vision Res. 21, 791–799 (1981).
[CrossRef] [PubMed]

G. E. Legge, J. M. Foley, “Contrast masking in human vision,” J. Opt. Soc. Am. 70, 1458–1471 (1980).
[CrossRef] [PubMed]

Levi, D. M.

D. S. Loshin, D. M. Levi, “Suprathreshold contrast perception in functional amblyopia,” Doc. Ophthalmol. 55, 213–236 (1983).
[CrossRef] [PubMed]

Loshin, D. S.

D. S. Loshin, D. M. Levi, “Suprathreshold contrast perception in functional amblyopia,” Doc. Ophthalmol. 55, 213–236 (1983).
[CrossRef] [PubMed]

Mori, T.

A. Watanabe, T. Mori, S. Nagata, K. Hiwatashi, “Spatial sine-wave responses of the human visual system,” Vision Res. 8, 1245–1263 (1968).
[CrossRef] [PubMed]

Muncey, J. P. J.

C. Blakemore, J. P. J. Muncey, R. M. Ridley, “Stimulus specificity in the human visual system,” Vision Res. 13, 195–1931 (1973).
[CrossRef]

Nagata, S.

A. Watanabe, T. Mori, S. Nagata, K. Hiwatashi, “Spatial sine-wave responses of the human visual system,” Vision Res. 8, 1245–1263 (1968).
[CrossRef] [PubMed]

Quick, R. F.

J. R. Hamerly, R. F. Quick, T. A. Reichert, “A study of grating contrast judgment,” Vision Res. 17, 201–207 (1977).
[CrossRef] [PubMed]

Reichert, T. A.

J. R. Hamerly, R. F. Quick, T. A. Reichert, “A study of grating contrast judgment,” Vision Res. 17, 201–207 (1977).
[CrossRef] [PubMed]

Ridley, R. M.

C. Blakemore, J. P. J. Muncey, R. M. Ridley, “Stimulus specificity in the human visual system,” Vision Res. 13, 195–1931 (1973).
[CrossRef]

Rovamo, J.

V. Virsu, J. Rovamo, “Visual resolution, contrast sensitivity and the cortical magnification factor,” Exp. Brain Res. 37, 475–494 (1979).
[CrossRef]

J. Rovamo, V. Virsu, “An estimation and application of the human cortical magnification factor,” Exp. Brain Res. 37, 495–510 (1979).
[CrossRef] [PubMed]

Rubin, G. S.

J. Gottesman, G. S. Rubin, G. E. Legge, “A power law for perceived contrast in human vision,” Vision Res. 21, 791–799 (1981).
[CrossRef] [PubMed]

Stevens, J. C.

Stevens, S. S.

J. C. Stevens, S. S. Stevens, “Brightness function: effects of adaptation,” J. Opt. Soc. Am. 53, 375–385 (1963).
[CrossRef] [PubMed]

S. S. Stevens, “The direct estimation of sensory magnitudes—loudness,” Am. J. Psychol. 69, 1–25 (1956).
[CrossRef] [PubMed]

Sullivan, G. D.

M. A. Georgeson, G. D. Sullivan, “Contrast constancy: deblurring in human vision by spatial frequency channels,” J. Physiol. (London) 252, 627–656 (1975).

Swanson, W. H.

W. H. Swanson, H. R. Wilson, S. C. Giese, “Contrast matching data predicted from contrast increment thresholds,” Vision Res. 24, 63–75 (1984).
[CrossRef] [PubMed]

Synder, A. Z.

B. M. Dow, A. Z. Synder, R. B. Vautin, R. Bauer, “Magnification factor and receptive field size in foveal striate cortex of the monkey,” Exp. Brain Res. 44, 213–228 (1981).
[CrossRef] [PubMed]

Takahashi, S.

S. Takahashi, Y. Ejima, “Dependence of apparent contrast of a sinusoidal grating on stimulus size,” J. Opt. Soc. Am. A 12, 1197–1201 (1984).
[CrossRef]

Vautin, R. B.

B. M. Dow, A. Z. Synder, R. B. Vautin, R. Bauer, “Magnification factor and receptive field size in foveal striate cortex of the monkey,” Exp. Brain Res. 44, 213–228 (1981).
[CrossRef] [PubMed]

Virsu, V.

J. Rovamo, V. Virsu, “An estimation and application of the human cortical magnification factor,” Exp. Brain Res. 37, 495–510 (1979).
[CrossRef] [PubMed]

V. Virsu, J. Rovamo, “Visual resolution, contrast sensitivity and the cortical magnification factor,” Exp. Brain Res. 37, 475–494 (1979).
[CrossRef]

Watanabe, A.

A. Watanabe, T. Mori, S. Nagata, K. Hiwatashi, “Spatial sine-wave responses of the human visual system,” Vision Res. 8, 1245–1263 (1968).
[CrossRef] [PubMed]

Wiesel, T. N.

D. H. Hubel, T. N. Wiesel, “Uniformity of monkey striate cortex. A parallel relationship between field size, scatter, and magnification factor,” J. Comp. Neurol. 158, 295–306 (1974).
[CrossRef] [PubMed]

Wilson, H. R.

W. H. Swanson, H. R. Wilson, S. C. Giese, “Contrast matching data predicted from contrast increment thresholds,” Vision Res. 24, 63–75 (1984).
[CrossRef] [PubMed]

Witteridge, D.

P. M. Daniel, D. Witteridge, “The representation of the visual field in the cerebral cortex in monkey,” J. Physiol. 186, 558–578 (1961).

Am. J. Psychol. (1)

S. S. Stevens, “The direct estimation of sensory magnitudes—loudness,” Am. J. Psychol. 69, 1–25 (1956).
[CrossRef] [PubMed]

Doc. Ophthalmol. (1)

D. S. Loshin, D. M. Levi, “Suprathreshold contrast perception in functional amblyopia,” Doc. Ophthalmol. 55, 213–236 (1983).
[CrossRef] [PubMed]

Exp. Brain Res. (3)

B. M. Dow, A. Z. Synder, R. B. Vautin, R. Bauer, “Magnification factor and receptive field size in foveal striate cortex of the monkey,” Exp. Brain Res. 44, 213–228 (1981).
[CrossRef] [PubMed]

V. Virsu, J. Rovamo, “Visual resolution, contrast sensitivity and the cortical magnification factor,” Exp. Brain Res. 37, 475–494 (1979).
[CrossRef]

J. Rovamo, V. Virsu, “An estimation and application of the human cortical magnification factor,” Exp. Brain Res. 37, 495–510 (1979).
[CrossRef] [PubMed]

Invest. Ophthalmol. Vis. Sci. Suppl. (1)

M. W. Cannon, “Range effects in magnitude estimation of contrast,” Invest. Ophthalmol. Vis. Sci. Suppl. 25, 296 (1984).

J. Comp. Neurol. (1)

D. H. Hubel, T. N. Wiesel, “Uniformity of monkey striate cortex. A parallel relationship between field size, scatter, and magnification factor,” J. Comp. Neurol. 158, 295–306 (1974).
[CrossRef] [PubMed]

J. Opt. Soc. Am. (3)

J. Opt. Soc. Am. A (1)

S. Takahashi, Y. Ejima, “Dependence of apparent contrast of a sinusoidal grating on stimulus size,” J. Opt. Soc. Am. A 12, 1197–1201 (1984).
[CrossRef]

J. Physiol. (1)

P. M. Daniel, D. Witteridge, “The representation of the visual field in the cerebral cortex in monkey,” J. Physiol. 186, 558–578 (1961).

J. Physiol. (London) (1)

M. A. Georgeson, G. D. Sullivan, “Contrast constancy: deblurring in human vision by spatial frequency channels,” J. Physiol. (London) 252, 627–656 (1975).

Nature (1)

R. F. Hess, A. Bradley, “Contrast perception above threshold is only minimally impaired in human amblyopia,” Nature 287, 463–464 (1980).
[CrossRef] [PubMed]

Vision Res. (10)

W. H. Swanson, H. R. Wilson, S. C. Giese, “Contrast matching data predicted from contrast increment thresholds,” Vision Res. 24, 63–75 (1984).
[CrossRef] [PubMed]

G. E. Legge, “A power law for contrast discrimination,” Vision Res. 21, 457–467 (1981).
[CrossRef] [PubMed]

A. Watanabe, T. Mori, S. Nagata, K. Hiwatashi, “Spatial sine-wave responses of the human visual system,” Vision Res. 8, 1245–1263 (1968).
[CrossRef] [PubMed]

C. Blakemore, J. P. J. Muncey, R. M. Ridley, “Stimulus specificity in the human visual system,” Vision Res. 13, 195–1931 (1973).
[CrossRef]

O. Franzen, M. Berkley, “Apparent contrast as a function of modulation depth and spatial frequency: a comparison between perceptual and electrophysiological measures,” Vision Res. 15, 655–660 (1975).
[CrossRef] [PubMed]

J. R. Hamerly, R. F. Quick, T. A. Reichert, “A study of grating contrast judgment,” Vision Res. 17, 201–207 (1977).
[CrossRef] [PubMed]

M. W. Cannon, “Contrast sensation: a linear function of stimulus contrast,” Vision Res. 19, 1405–1452 (1979).
[CrossRef]

J. Gottesman, G. S. Rubin, G. E. Legge, “A power law for perceived contrast in human vision,” Vision Res. 21, 791–799 (1981).
[CrossRef] [PubMed]

M. W. Cannon, “A study of stimulus range effects in free modulus magnitude estimation of contrast,” Vision Res. 24, 1049–1055 (1984).
[CrossRef] [PubMed]

C. Guld, A. Bertulis, “Representation of fovea in the striate cortex of vervet monkey, Cercopithecus aethiops pygerythrus,” Vision Res. 16, 629–631 (1976).
[CrossRef] [PubMed]

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Figures (7)

Fig. 1
Fig. 1

Perceived-contrast estimates for stimuli with different contrast ranges (0.6 and 1.9 log units), presented in an interleaved manner in a single experimental session. If these stimuli are presented independently, previous research (see text) has shown that the exponent for the short-range stimulus will be artificially high. The data in the figure demonstrate that if the two sets of stimuli are presented interleaved in the same experimental session, the range effect is no longer a factor, and subjects can accurately estimate the contrast of the short-range stimulus relative to the long-range stimulus. This is important for subsequent experiments in which perceived contrast will be estimated for foveal and peripheral viewing, since the available contrast range in the periphery is small.

Fig. 2
Fig. 2

Perceived-contrast functions for foveal viewing. The individual data points are geometric means, and standard deviations of normalized contrast estimates from nine subjects and were obtained in three experiments. These involved presentations of a 4-c/deg grating interleaved with a 2-, 8-, or 16-c/deg grating. The curves represented least-square fits of functions of the form PC = k(CT)α where PC is perceived contrast, T is threshold, and C is the physical contrast of the stimuli. Threshold contrasts are indicated by the arrows just above the contrast axis.

Fig. 3
Fig. 3

Equal perceived-contrast contours derived from the perceived-contrast functions in Fig. 2.

Fig. 4
Fig. 4

Foveal and peripheral perceived-contrast functions for 2- and 4-c/deg stimuli. The perceived-contrast data points are geometric means and standard deviations of normalized perceived-contrast estimates from nine subjects. The perceived-contrast data in each panel represent the results of a single experimental session for each subject, so all contrast estimates were apparently made using the same perceptual scale. Eccentricities are indicated by the numbers near the bottom of each panel, and thresholds are indicated as in Fig. 2 by the arrows adjacent to the contrast axis at the bottom of each panel.

Fig. 5
Fig. 5

Foveal and peripheral perceived-contrast functions for 8 and 16 c/deg. Data description is the same as for Fig. 4. At these spatial frequencies perceived-contrast functions for higher eccentricities approach but never reach the foveal perceived-contrast function.

Fig. 6
Fig. 6

Foveal perceived-contrast functions for stimuli of different spatial extent. Data description is the same as in previous figures, and again perceived-contrast functions of the form PC = k(CT)α are fitted. Whereas thresholds differ by about a factor of 2, the perceived-contrast functions approach equality at high physical contrast.

Fig. 7
Fig. 7

Summary of perceived-contrast data plotted as a function of contrast minus threshold. The data points are the data of Figs. 2 and 46 replotted with new horizontal-axis coordinates and displaced vertically for clarity. Correspondence between letter label and data set may be found in the text. This transformation to CT coordinates produces a rather uniform clustering of all data sets around power functions with similar exponents.

Tables (1)

Tables Icon

Table 1 Individual Subject Exponents for Perceived-Contrast Functions Displayed in Fig. 2

Equations (1)

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F = a 1 ( | r | α + β ) / ( | r | β + a 2 β ) .

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