Abstract

Contrast detection thresholds for moving spatial sine wave gratings were obtained, at the fovea, and at eccentricities of 1°, 2°, 4°, 6°, and 8° on the nasal horizontal meridian, for two subjects. The target field subtended 30 × 30 minutes of arc. The spatial frequency range extended from 2 cpd up to the spatial resolution limit, the temporal frequency range from 0.1 Hz up to the CFF. Mean retinal illuminance was 10 trolands. We find for these conditions: (i) Contrast detection thresholds are higher, the higher the spatial and/or temporal frequency of the stimulus. (ii) Acuity appears to be independent of the temporal frequency, the CFF appears to be independent of the spatial frequency. (iii) The higher the eccentricity, the higher the contrast detection threshold for any drifting sine wave pattern. The threshold doubles roughly any 2°–3° for spatial frequencies of 2–20 cpd, except that the visual field for a given fineness of grating is blind beyond a certain critical eccentricity. This critical eccentricity is a monotonically decreasing function of the spatial frequency of the grating. These measurements do not support the hypothesis that coarse patterns are preferentially detected at extrafoveal sites in the visual field.

© 1978 Optical Society of America

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References

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  1. M. Millodot, “Foveal and extra-foveal acuity with and without stabilized retinal images,” Br. J. Physiol. Opt. 23, 75–106 (1966).
    [PubMed]
  2. E. Pöppel and L. O. Harvey, “Light-difference threshold and subjective brightness in the periphery of the visual field,” Psychol. Forsch. 36, 145–161 (1973).
    [CrossRef] [PubMed]
  3. M. A. Berkley, F. Kitterle, and D. W. Watkins, “Grating visibility as a function of orientation and retinal eccentricity,” Vis. Res. 15, 239–244 (1975).
    [CrossRef] [PubMed]
  4. B. O’Brien, “Vision and resolution in the central retina,” J. Opt. Soc. Am. 41, 882–894 (1951).
    [CrossRef]
  5. F. L. van Nes, J. J. Koenderink, H. Nas, and M. A. Bouman, “Spatiotemporal modulation transfer in the human eye,” J. Opt. Soc. Am. 57, 1082–1087 (1967).
    [CrossRef] [PubMed]
  6. F. L. van Nes, “Experimental studies in spatiotemporal contrast transfer by the human eye” (Thesis, University of Utrecht, 1968).
  7. C. R. Sharpe, “The contrast sensitivity of the peripheral visual field to drifting sinusoidal gratings,” Vis. Res. 14, 905–906 (1974).
    [CrossRef]
  8. J. J. Koenderink, M. A. Bouman, A. E. Bueno de Mesquita, and S. Slappendel, “Perimetry of contrast detection thresholds of moving spatial sine wave patterns. II. The far peripheral visual field (eccentricity 0°–50°),” J. Opt. Soc. Am. 68, 850–854 (1978).
    [CrossRef] [PubMed]
  9. J. J. Koenderink, M. A. Bouman, A. E. Bueno de Mesquita, and S. Slappendel, “Perimetry of contrast detection thresholds of moving spatial sine wave patterns. III. The target extent as a sensitivity controlling parameter,” J. Opt. Soc. Am. 68, 854–860 (1978).
    [CrossRef] [PubMed]
  10. J. J. Koenderink, M. A. Bouman, A. E. Bueno de Mesquita, and S. Slappendel, “Perimetry of contrast detection thresholds of moving spatial sine wave patterns. IV. The influence of the mean retinal illuminance,” J. Opt. Soc. Am. 68, 860–865 (1978).
    [CrossRef] [PubMed]
  11. C. E. Ferree, R. Rand, and C. Hardy, “Refraction for the peripheral field of vision,” A.M.A. Archs. Ophthal. 5, 717–731 (1931).
    [CrossRef]
  12. M. Millodot, C. A. Johnson, A. Lamont, and H. W. Leibowitz, “Effect of dioptrics on peripheral visual acuity,” Vis. Res. 15, 1357–1362 (1975).
    [CrossRef] [PubMed]
  13. F. Rempt, J. Hoogerheide, and W. P. H. Hoogenboom, “Influence of correction of peripheral refractive errors on peripheral static vision,” Ophthalmologica, Basel,  173, 128–135 (1976).
    [CrossRef] [PubMed]
  14. Dor (1873) who utilized a grating found that at an eccentricity of 5° the acuity was only ¼ of the foveal acuity; Wertheim (1887) utilized two points of light and found an acuity of 0.4 at an eccentricity of 5°, using a grating he found an acuity of 0.3 at an eccentricity of 5°; Ludvigh (1941) using Snellen letters found an acuity of 0.3 at an eccentricity of 5°. See Millodot (Ref. 1).
  15. Berkley and et al. (Ref. 3) report an acuity of 0.2–0.4 at an eccentricity of 8°; Limb and Rubinstein18report a doubling of the width of the line-spread function from the fovea to an eccentricity of 8°.
  16. R. Hilz and C. R. Cavonius, “Functional organization of the peripheral retina: sensitivity to periodic stimuli,” Vis. Res. 14, 1333–1337 (1974).
    [CrossRef] [PubMed]
  17. M. Hines, “Line spread function variation near the fovea,” Vis. Res. 16, 567–572 (1976).
    [CrossRef] [PubMed]
  18. J. O. Limb and C. B. Rubinstein, “A model of threshold vision incorporating inhomogeneity of the visual field,” Vis. Res. 17, 571–584 (1977).
    [CrossRef] [PubMed]
  19. B. S. Hylkema (1942), quoted by W. A. van de Grind, O.-J. Grüsser, and H. U. Lunkenheimer, “Temporal transfer properties of the afferent visual system. Psychophysical, neurophysiological and theoretical investigations,” in Handbook of Sensory Physiology, edited by H. Autrum, R. Jung, W. R. Loewenstein, D. M. McKay, and H. L. Teuber (Springer-Verlag, Berlin-Heidelberg-New York, 1973). Vol. VII/3A, Central processing of visual information, Part A, pp. 431–573.
  20. A. J. van Doorn, J. J. Koenderink, and M. A. Bouman, “The influence of the retinal inhomogeneity on the perception of spatial patterns,” Kybernetik 10, 223–230 (1972).
    [CrossRef] [PubMed]
  21. H. R. Wilson, “The significance of frequency gradients in binocular grating perception,” Vis. Res. 16, 983–989 (1976).
    [CrossRef] [PubMed]
  22. G. J. van der Wildt, C. J. Keemink, and G. van den Brink, “Gradient detection and contrast transfer by the human eye,” Vis. Res. 16, 1047–1053 (1976).
    [CrossRef] [PubMed]
  23. N. Graham, J. G. Robson, and J. Nachmias, “Grating summation in fovea and periphery,” ARVO Spring Meeting, Sarasota (1977).
  24. J. J. Koenderink, “Current models of contrast processing,” in Spatial Contrast, edited by H. Spekreÿse and L. H. van der Tweel (North-Holland, Amsterdam, 1977).
  25. O. Bryngdahl, “Perceived contrast variation with eccentricity of spatial sine-wave stimuli,” Vis. Res. 6, 553–565 (1966).
    [CrossRef]

1978 (3)

1977 (1)

J. O. Limb and C. B. Rubinstein, “A model of threshold vision incorporating inhomogeneity of the visual field,” Vis. Res. 17, 571–584 (1977).
[CrossRef] [PubMed]

1976 (4)

H. R. Wilson, “The significance of frequency gradients in binocular grating perception,” Vis. Res. 16, 983–989 (1976).
[CrossRef] [PubMed]

G. J. van der Wildt, C. J. Keemink, and G. van den Brink, “Gradient detection and contrast transfer by the human eye,” Vis. Res. 16, 1047–1053 (1976).
[CrossRef] [PubMed]

F. Rempt, J. Hoogerheide, and W. P. H. Hoogenboom, “Influence of correction of peripheral refractive errors on peripheral static vision,” Ophthalmologica, Basel,  173, 128–135 (1976).
[CrossRef] [PubMed]

M. Hines, “Line spread function variation near the fovea,” Vis. Res. 16, 567–572 (1976).
[CrossRef] [PubMed]

1975 (2)

M. Millodot, C. A. Johnson, A. Lamont, and H. W. Leibowitz, “Effect of dioptrics on peripheral visual acuity,” Vis. Res. 15, 1357–1362 (1975).
[CrossRef] [PubMed]

M. A. Berkley, F. Kitterle, and D. W. Watkins, “Grating visibility as a function of orientation and retinal eccentricity,” Vis. Res. 15, 239–244 (1975).
[CrossRef] [PubMed]

1974 (2)

C. R. Sharpe, “The contrast sensitivity of the peripheral visual field to drifting sinusoidal gratings,” Vis. Res. 14, 905–906 (1974).
[CrossRef]

R. Hilz and C. R. Cavonius, “Functional organization of the peripheral retina: sensitivity to periodic stimuli,” Vis. Res. 14, 1333–1337 (1974).
[CrossRef] [PubMed]

1973 (1)

E. Pöppel and L. O. Harvey, “Light-difference threshold and subjective brightness in the periphery of the visual field,” Psychol. Forsch. 36, 145–161 (1973).
[CrossRef] [PubMed]

1972 (1)

A. J. van Doorn, J. J. Koenderink, and M. A. Bouman, “The influence of the retinal inhomogeneity on the perception of spatial patterns,” Kybernetik 10, 223–230 (1972).
[CrossRef] [PubMed]

1967 (1)

1966 (2)

O. Bryngdahl, “Perceived contrast variation with eccentricity of spatial sine-wave stimuli,” Vis. Res. 6, 553–565 (1966).
[CrossRef]

M. Millodot, “Foveal and extra-foveal acuity with and without stabilized retinal images,” Br. J. Physiol. Opt. 23, 75–106 (1966).
[PubMed]

1951 (1)

1931 (1)

C. E. Ferree, R. Rand, and C. Hardy, “Refraction for the peripheral field of vision,” A.M.A. Archs. Ophthal. 5, 717–731 (1931).
[CrossRef]

Berkley,

Berkley and et al. (Ref. 3) report an acuity of 0.2–0.4 at an eccentricity of 8°; Limb and Rubinstein18report a doubling of the width of the line-spread function from the fovea to an eccentricity of 8°.

Berkley, M. A.

M. A. Berkley, F. Kitterle, and D. W. Watkins, “Grating visibility as a function of orientation and retinal eccentricity,” Vis. Res. 15, 239–244 (1975).
[CrossRef] [PubMed]

Bouman, M. A.

Bryngdahl, O.

O. Bryngdahl, “Perceived contrast variation with eccentricity of spatial sine-wave stimuli,” Vis. Res. 6, 553–565 (1966).
[CrossRef]

Bueno de Mesquita, A. E.

Cavonius, C. R.

R. Hilz and C. R. Cavonius, “Functional organization of the peripheral retina: sensitivity to periodic stimuli,” Vis. Res. 14, 1333–1337 (1974).
[CrossRef] [PubMed]

Dor,

Dor (1873) who utilized a grating found that at an eccentricity of 5° the acuity was only ¼ of the foveal acuity; Wertheim (1887) utilized two points of light and found an acuity of 0.4 at an eccentricity of 5°, using a grating he found an acuity of 0.3 at an eccentricity of 5°; Ludvigh (1941) using Snellen letters found an acuity of 0.3 at an eccentricity of 5°. See Millodot (Ref. 1).

Ferree, C. E.

C. E. Ferree, R. Rand, and C. Hardy, “Refraction for the peripheral field of vision,” A.M.A. Archs. Ophthal. 5, 717–731 (1931).
[CrossRef]

Graham, N.

N. Graham, J. G. Robson, and J. Nachmias, “Grating summation in fovea and periphery,” ARVO Spring Meeting, Sarasota (1977).

Grüsser, O.-J.

B. S. Hylkema (1942), quoted by W. A. van de Grind, O.-J. Grüsser, and H. U. Lunkenheimer, “Temporal transfer properties of the afferent visual system. Psychophysical, neurophysiological and theoretical investigations,” in Handbook of Sensory Physiology, edited by H. Autrum, R. Jung, W. R. Loewenstein, D. M. McKay, and H. L. Teuber (Springer-Verlag, Berlin-Heidelberg-New York, 1973). Vol. VII/3A, Central processing of visual information, Part A, pp. 431–573.

Hardy, C.

C. E. Ferree, R. Rand, and C. Hardy, “Refraction for the peripheral field of vision,” A.M.A. Archs. Ophthal. 5, 717–731 (1931).
[CrossRef]

Harvey, L. O.

E. Pöppel and L. O. Harvey, “Light-difference threshold and subjective brightness in the periphery of the visual field,” Psychol. Forsch. 36, 145–161 (1973).
[CrossRef] [PubMed]

Hilz, R.

R. Hilz and C. R. Cavonius, “Functional organization of the peripheral retina: sensitivity to periodic stimuli,” Vis. Res. 14, 1333–1337 (1974).
[CrossRef] [PubMed]

Hines, M.

M. Hines, “Line spread function variation near the fovea,” Vis. Res. 16, 567–572 (1976).
[CrossRef] [PubMed]

Hoogenboom, W. P. H.

F. Rempt, J. Hoogerheide, and W. P. H. Hoogenboom, “Influence of correction of peripheral refractive errors on peripheral static vision,” Ophthalmologica, Basel,  173, 128–135 (1976).
[CrossRef] [PubMed]

Hoogerheide, J.

F. Rempt, J. Hoogerheide, and W. P. H. Hoogenboom, “Influence of correction of peripheral refractive errors on peripheral static vision,” Ophthalmologica, Basel,  173, 128–135 (1976).
[CrossRef] [PubMed]

Hylkema, B. S.

B. S. Hylkema (1942), quoted by W. A. van de Grind, O.-J. Grüsser, and H. U. Lunkenheimer, “Temporal transfer properties of the afferent visual system. Psychophysical, neurophysiological and theoretical investigations,” in Handbook of Sensory Physiology, edited by H. Autrum, R. Jung, W. R. Loewenstein, D. M. McKay, and H. L. Teuber (Springer-Verlag, Berlin-Heidelberg-New York, 1973). Vol. VII/3A, Central processing of visual information, Part A, pp. 431–573.

Johnson, C. A.

M. Millodot, C. A. Johnson, A. Lamont, and H. W. Leibowitz, “Effect of dioptrics on peripheral visual acuity,” Vis. Res. 15, 1357–1362 (1975).
[CrossRef] [PubMed]

Keemink, C. J.

G. J. van der Wildt, C. J. Keemink, and G. van den Brink, “Gradient detection and contrast transfer by the human eye,” Vis. Res. 16, 1047–1053 (1976).
[CrossRef] [PubMed]

Kitterle, F.

M. A. Berkley, F. Kitterle, and D. W. Watkins, “Grating visibility as a function of orientation and retinal eccentricity,” Vis. Res. 15, 239–244 (1975).
[CrossRef] [PubMed]

Koenderink, J. J.

Lamont, A.

M. Millodot, C. A. Johnson, A. Lamont, and H. W. Leibowitz, “Effect of dioptrics on peripheral visual acuity,” Vis. Res. 15, 1357–1362 (1975).
[CrossRef] [PubMed]

Leibowitz, H. W.

M. Millodot, C. A. Johnson, A. Lamont, and H. W. Leibowitz, “Effect of dioptrics on peripheral visual acuity,” Vis. Res. 15, 1357–1362 (1975).
[CrossRef] [PubMed]

Limb, J. O.

J. O. Limb and C. B. Rubinstein, “A model of threshold vision incorporating inhomogeneity of the visual field,” Vis. Res. 17, 571–584 (1977).
[CrossRef] [PubMed]

Lunkenheimer, H. U.

B. S. Hylkema (1942), quoted by W. A. van de Grind, O.-J. Grüsser, and H. U. Lunkenheimer, “Temporal transfer properties of the afferent visual system. Psychophysical, neurophysiological and theoretical investigations,” in Handbook of Sensory Physiology, edited by H. Autrum, R. Jung, W. R. Loewenstein, D. M. McKay, and H. L. Teuber (Springer-Verlag, Berlin-Heidelberg-New York, 1973). Vol. VII/3A, Central processing of visual information, Part A, pp. 431–573.

Millodot, M.

M. Millodot, C. A. Johnson, A. Lamont, and H. W. Leibowitz, “Effect of dioptrics on peripheral visual acuity,” Vis. Res. 15, 1357–1362 (1975).
[CrossRef] [PubMed]

M. Millodot, “Foveal and extra-foveal acuity with and without stabilized retinal images,” Br. J. Physiol. Opt. 23, 75–106 (1966).
[PubMed]

Nachmias, J.

N. Graham, J. G. Robson, and J. Nachmias, “Grating summation in fovea and periphery,” ARVO Spring Meeting, Sarasota (1977).

Nas, H.

O’Brien, B.

Pöppel, E.

E. Pöppel and L. O. Harvey, “Light-difference threshold and subjective brightness in the periphery of the visual field,” Psychol. Forsch. 36, 145–161 (1973).
[CrossRef] [PubMed]

Rand, R.

C. E. Ferree, R. Rand, and C. Hardy, “Refraction for the peripheral field of vision,” A.M.A. Archs. Ophthal. 5, 717–731 (1931).
[CrossRef]

Rempt, F.

F. Rempt, J. Hoogerheide, and W. P. H. Hoogenboom, “Influence of correction of peripheral refractive errors on peripheral static vision,” Ophthalmologica, Basel,  173, 128–135 (1976).
[CrossRef] [PubMed]

Robson, J. G.

N. Graham, J. G. Robson, and J. Nachmias, “Grating summation in fovea and periphery,” ARVO Spring Meeting, Sarasota (1977).

Rubinstein, C. B.

J. O. Limb and C. B. Rubinstein, “A model of threshold vision incorporating inhomogeneity of the visual field,” Vis. Res. 17, 571–584 (1977).
[CrossRef] [PubMed]

Sharpe, C. R.

C. R. Sharpe, “The contrast sensitivity of the peripheral visual field to drifting sinusoidal gratings,” Vis. Res. 14, 905–906 (1974).
[CrossRef]

Slappendel, S.

van de Grind, W. A.

B. S. Hylkema (1942), quoted by W. A. van de Grind, O.-J. Grüsser, and H. U. Lunkenheimer, “Temporal transfer properties of the afferent visual system. Psychophysical, neurophysiological and theoretical investigations,” in Handbook of Sensory Physiology, edited by H. Autrum, R. Jung, W. R. Loewenstein, D. M. McKay, and H. L. Teuber (Springer-Verlag, Berlin-Heidelberg-New York, 1973). Vol. VII/3A, Central processing of visual information, Part A, pp. 431–573.

van den Brink, G.

G. J. van der Wildt, C. J. Keemink, and G. van den Brink, “Gradient detection and contrast transfer by the human eye,” Vis. Res. 16, 1047–1053 (1976).
[CrossRef] [PubMed]

van der Wildt, G. J.

G. J. van der Wildt, C. J. Keemink, and G. van den Brink, “Gradient detection and contrast transfer by the human eye,” Vis. Res. 16, 1047–1053 (1976).
[CrossRef] [PubMed]

van Doorn, A. J.

A. J. van Doorn, J. J. Koenderink, and M. A. Bouman, “The influence of the retinal inhomogeneity on the perception of spatial patterns,” Kybernetik 10, 223–230 (1972).
[CrossRef] [PubMed]

van Nes, F. L.

F. L. van Nes, J. J. Koenderink, H. Nas, and M. A. Bouman, “Spatiotemporal modulation transfer in the human eye,” J. Opt. Soc. Am. 57, 1082–1087 (1967).
[CrossRef] [PubMed]

F. L. van Nes, “Experimental studies in spatiotemporal contrast transfer by the human eye” (Thesis, University of Utrecht, 1968).

Watkins, D. W.

M. A. Berkley, F. Kitterle, and D. W. Watkins, “Grating visibility as a function of orientation and retinal eccentricity,” Vis. Res. 15, 239–244 (1975).
[CrossRef] [PubMed]

Wilson, H. R.

H. R. Wilson, “The significance of frequency gradients in binocular grating perception,” Vis. Res. 16, 983–989 (1976).
[CrossRef] [PubMed]

A.M.A. Archs. Ophthal. (1)

C. E. Ferree, R. Rand, and C. Hardy, “Refraction for the peripheral field of vision,” A.M.A. Archs. Ophthal. 5, 717–731 (1931).
[CrossRef]

Br. J. Physiol. Opt. (1)

M. Millodot, “Foveal and extra-foveal acuity with and without stabilized retinal images,” Br. J. Physiol. Opt. 23, 75–106 (1966).
[PubMed]

J. Opt. Soc. Am. (5)

Kybernetik (1)

A. J. van Doorn, J. J. Koenderink, and M. A. Bouman, “The influence of the retinal inhomogeneity on the perception of spatial patterns,” Kybernetik 10, 223–230 (1972).
[CrossRef] [PubMed]

Ophthalmologica, Basel (1)

F. Rempt, J. Hoogerheide, and W. P. H. Hoogenboom, “Influence of correction of peripheral refractive errors on peripheral static vision,” Ophthalmologica, Basel,  173, 128–135 (1976).
[CrossRef] [PubMed]

Psychol. Forsch. (1)

E. Pöppel and L. O. Harvey, “Light-difference threshold and subjective brightness in the periphery of the visual field,” Psychol. Forsch. 36, 145–161 (1973).
[CrossRef] [PubMed]

Vis. Res. (9)

M. A. Berkley, F. Kitterle, and D. W. Watkins, “Grating visibility as a function of orientation and retinal eccentricity,” Vis. Res. 15, 239–244 (1975).
[CrossRef] [PubMed]

M. Millodot, C. A. Johnson, A. Lamont, and H. W. Leibowitz, “Effect of dioptrics on peripheral visual acuity,” Vis. Res. 15, 1357–1362 (1975).
[CrossRef] [PubMed]

H. R. Wilson, “The significance of frequency gradients in binocular grating perception,” Vis. Res. 16, 983–989 (1976).
[CrossRef] [PubMed]

G. J. van der Wildt, C. J. Keemink, and G. van den Brink, “Gradient detection and contrast transfer by the human eye,” Vis. Res. 16, 1047–1053 (1976).
[CrossRef] [PubMed]

R. Hilz and C. R. Cavonius, “Functional organization of the peripheral retina: sensitivity to periodic stimuli,” Vis. Res. 14, 1333–1337 (1974).
[CrossRef] [PubMed]

M. Hines, “Line spread function variation near the fovea,” Vis. Res. 16, 567–572 (1976).
[CrossRef] [PubMed]

J. O. Limb and C. B. Rubinstein, “A model of threshold vision incorporating inhomogeneity of the visual field,” Vis. Res. 17, 571–584 (1977).
[CrossRef] [PubMed]

C. R. Sharpe, “The contrast sensitivity of the peripheral visual field to drifting sinusoidal gratings,” Vis. Res. 14, 905–906 (1974).
[CrossRef]

O. Bryngdahl, “Perceived contrast variation with eccentricity of spatial sine-wave stimuli,” Vis. Res. 6, 553–565 (1966).
[CrossRef]

Other (6)

Dor (1873) who utilized a grating found that at an eccentricity of 5° the acuity was only ¼ of the foveal acuity; Wertheim (1887) utilized two points of light and found an acuity of 0.4 at an eccentricity of 5°, using a grating he found an acuity of 0.3 at an eccentricity of 5°; Ludvigh (1941) using Snellen letters found an acuity of 0.3 at an eccentricity of 5°. See Millodot (Ref. 1).

Berkley and et al. (Ref. 3) report an acuity of 0.2–0.4 at an eccentricity of 8°; Limb and Rubinstein18report a doubling of the width of the line-spread function from the fovea to an eccentricity of 8°.

B. S. Hylkema (1942), quoted by W. A. van de Grind, O.-J. Grüsser, and H. U. Lunkenheimer, “Temporal transfer properties of the afferent visual system. Psychophysical, neurophysiological and theoretical investigations,” in Handbook of Sensory Physiology, edited by H. Autrum, R. Jung, W. R. Loewenstein, D. M. McKay, and H. L. Teuber (Springer-Verlag, Berlin-Heidelberg-New York, 1973). Vol. VII/3A, Central processing of visual information, Part A, pp. 431–573.

N. Graham, J. G. Robson, and J. Nachmias, “Grating summation in fovea and periphery,” ARVO Spring Meeting, Sarasota (1977).

J. J. Koenderink, “Current models of contrast processing,” in Spatial Contrast, edited by H. Spekreÿse and L. H. van der Tweel (North-Holland, Amsterdam, 1977).

F. L. van Nes, “Experimental studies in spatiotemporal contrast transfer by the human eye” (Thesis, University of Utrecht, 1968).

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Figures (5)

FIG. 1
FIG. 1

The refractive condition of the peripheral fields of the right eyes of the subjects AB and SS. On the abscissa the eccentricity in degrees of visual angle; on the ordinate the necessary correction in diopters. Measurements were confined to the nasal meridian. Circles with the vertical bar refer to the vertical focal line, circles with the horizontal bar to the horizontal focal line.

FIG. 2
FIG. 2

Schematic diagrams of the spatiotemporal contrast detection threshold surface at eccentricities of 0°, 1°, 2°, 4°, 6°, and 8°. In the central white area contrast thresholds were below 3%; in the singly hatched area threshold contrasts ranged from 3% to 8%; in the doubly hatched area from 8% to 20%; in the black area from 20% to 50%. In the blank area at the high (spatial and/or temporal) frequency side of the diagrams thresholds were in excess of 50%. The location of the minimum contrast threshold is indicated with a white or black dot. Minimum values of the contrast detection threshold were: at the fovea 2.3% modulation depth; at eccentricities of 1°, 2°, 4°, 6°, and 8°, respectively, 2.9%, 5.6%, 16%, 21%, and 31% modulation depth. Subject SS. The spatial frequency scale is in cycles per degree, the temporal frequency scale in Hz.

FIG. 3
FIG. 3

Contrast detection thresholds (m in percent modulation depth) as a function of the spatial frequency (fs in cycles per degree) for a fixed temporal frequency of 0.5 Hz. The letters refer to the different eccentricities at which the curves were obtained: a at the fovea; b, c, d, e, and f at eccentricities of, respectively, 1°, 2°, 4°, 6°, and 8°. Subject SS.

FIG. 4
FIG. 4

Contrast detection thresholds (m in percent modulation depth) as a function of the temporal frequency (ft in Hz) for a fixed spatial frequency of 4 cycles per degree. The letters refer to the different eccentricities at which the curves were obtained: a at the fovea; b, c, d, e, and f at eccentricities of, respectively, 1°, 2°, 4°, 6°, and 8°. Subject SS. Note that the temporal frequency scale can also be used as a velocity scale, if one takes v (deg s−1) = 0.25ft (Hz).

FIG. 5
FIG. 5

At the ordinate is plotted R, the relative contrast threshold of a given spatial frequency at a certain eccentricity, on a logarithmic scale (that is, relative to the contrast threshold of that spatial frequency at the fovea). The eccentricity (in degrees) is plotted along the abscissa. Subject SS. The different curves are for different spatial frequencies. The numerical values of the spatial frequencies (in cycles per degree) are indicated at the endpoints of the curves. For reasons of clarity we omit the data points in this figure, but connect these points (always located at abscissa values of 0°, 1°, 2°, 4°, or 8°) with straight lines. If the grating proves invisible at the next higher eccentricity the curve is drawn vertically upwards.