Abstract

Spatiotemporal incremental and decremental thresholds were measured for a thin vertical line (target) positioned adjacent to a briefly presented vertical edge. A significant difference between the stimuli used here and those used in previous studies is the background level against which the edge was presented. Here the edge was formed by briefly decreasing the luminance of the left side of a light background. This novel condition was compared with the more usual condition in which the edge is formed by briefly increasing the luminance of the right half of a dark background. In a further test the buildup of threshold after an edge was switched on was also measured. When the target was presented on the side of the edge that remained fixed in luminance, a small but reliable threshold change adjacent to the edge was measured. The effect was much larger for measurements made on the side of the edge that changed in luminance; however, the spread was comparable for the two conditions. For the target presented on the light side of the edge, decremental thresholds were much larger than incremental thresholds. This is attributed, at least in part, to the different types of tasks required of the observer. Maximum temporal threshold elevation occurs at or just before (i.e., <16 msec) 0 asynchrony between edge and target. The results are interpreted at a qualitative level as supporting a receptive-field type of model in which the edge, at various spatiotemporal locations relative to the target, inhibits or excites activity at the receptive field centered on the target.

© 1981 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. H. R. Blackwell, “Neural theories of simple visual discriminations,” J. Opt. Soc. Am. 53, 129–160 (1963).
    [Crossref] [PubMed]
  2. F. W. Campbell, R. H. S. Carpenter, and J. Z. Levinson, “Visibility of a periodic patterns compared with that of sinusoidal gratings,” J. Physiol. London 204, 283–298 (1969).
  3. C. F. Stromeyer and B. Julesz, “Spatial-frequency masking in vision: critical bands and spread of masking,” J. Opt. Soc. Am. 62, 1221–1232 (1972).
    [Crossref] [PubMed]
  4. C. Blakemore and F. W. Campbell, “On the existence of neurones in the human visual system selectively sensitive to the orientation and size of retinal images,” J. Physiol. London 203, 237–260 (1969).
  5. G. Westheimer, “Spatial interaction in human cone vision,” J. Physiol. London 190, 139–154 (1967).
  6. A. Vassilev, “Contrast sensitivity near borders: significance of test stimulus form, size and duration,” Vision Res. 13, 719–730 (1973).
    [Crossref] [PubMed]
  7. S. Novak, “Invariance of detection thresholds across a light–dark boundary using dichoptic presentation,” J. Opt. Soc. Am. 57, 1059–1060 (1967).
    [Crossref] [PubMed]
  8. A. Fiorentini, M. Jeanne, and G. Toraldo di Francia, “Measurements of differential threshold in the presence of spatial illumination gradient,” Atti Fond. Giorgio Ronchi 10, 371–379 (1955).
  9. M. L. Matthews, “Appearance of mach bands for short durations and at sharply focused contours,” J. Opt. Soc. Am. 56, 1401–1402 (1966)
    [Crossref]
  10. F. X. J. Lukas, U. Tulunay-Keesey, and J. O. Limb, “Thresholds at luminance edges under stabilized viewing conditions,” J. Opt. Soc. Am. 70, 418–422 (1980).
    [Crossref] [PubMed]
  11. S. Hagiwara and T. Furukawa, “Incremental and decremental thresholds on mach patterns,” Inst. Electron. Commun. Eng. Trans. Jpn. J61-C, 248–255 (1978).
  12. S. Novak and G. Sperling, “Visual threshold near a continuously visible or a briefly presented light–dark boundary,” Opt. Acta 10, 187–191 (1963).
    [Crossref]
  13. D. A. Burkhardt, “Brightness and the increment threshold,” J. Opt. Soc. Am. 56, 979–981 (1966).
    [Crossref] [PubMed]
  14. S. Petry, D. C. Hood, and F. Goodkin, “Time course of lateral inhibition in the human visual system,” J. Opt. Soc. Am. 63, 385–386 (1973).
    [Crossref] [PubMed]
  15. D. Y. Teller, “Increment thresholds on black bars,” Vision Res. 8, 713–718 (1968).
    [Crossref] [PubMed]
  16. U. Tulunay-Keesey and A. Vassilev, “Foveal spatial sensitization with stabilized vision,” Vision Res. 14, 101–105 (1974).
    [Crossref] [PubMed]
  17. In view of the large number of measurements that were planned, it was decided not to use the more time-consuming criterion-free procedures. There is some evidence to suggest that, although thresholds measured by method of adjustment may be somewhat higher than those measured by forced choice, the functional relations change little [D. H. Kelly and R. E. Savoie, “A study of sine wave contrast sensitivity by two psychophysical methods,” Percept. Psychopys. 14, 313–318 (1973)].
    [Crossref]
  18. A. Fiorentini and M. T. Zoli, “Detection of a target superimposed to a step pattern of illumination,” Atti Fond. Giorgio Ronchi 21, 338–356 (1966).
  19. B. H. Crawford, “Visual adaptation in relation to brief conditioning stimuli,” Proc. R. Soc. London Ser. B 134, 283–302 (1948).
    [Crossref]
  20. J. Krauskopf, “Discrimination and detection of changes in luminance,” Vision Res. 20, 671–677 (1980).
    [Crossref] [PubMed]
  21. We attempted to create a spatial analogue of Krauskopf’s temporal experiment.20 The threshold for light or dark target lines was measured as before but on a plain background. Between presentations of the target, the subject viewed a set of highly visible, 1-min-wide, dark lines spaced 20 min apart. This was an attempt to modify the dark threshold selectively. Adapting to this grid of lines did not change the visibility of the light and dark target lines relative to each other or to their visibility in the unadapted condition.
  22. J. O. Limb and C. B. Rubinstein, “A model of threshold vision incorporating inhomogeneity of the visual field,” Vision Res. 17, 571–584 (1977).
    [Crossref] [PubMed]
  23. A. Fiorentini and M. T. Zoli, “Detection of a target superimposed to a step pattern of illumination,” Atti Fond. Giorgio Ronchi 22, 207–217 (1967).
  24. U. Tulunay-Keesey and R. M. Jones, “Spatial sensitization as a function of delay,” Vision Res. 17, 1191–1199 (1977).
    [Crossref] [PubMed]
  25. R. W. Ditchburn, Eyemovements and Visual Perception (Clarendon, Oxford, 1973), pp. 84–85, Table 4.1.
  26. U. Tulunay-Keesey and J. O. Limb, “Eye movements during short intervals,” presented at Association for Research in Vision and Ophthalmology annual meeting, Sarasota, Florida, April 27, 1981.
  27. C. Rashbass, “The visibility of transient changes of luminance,” J. Physiol. London 210, 165–186 (1970).

1980 (2)

1978 (1)

S. Hagiwara and T. Furukawa, “Incremental and decremental thresholds on mach patterns,” Inst. Electron. Commun. Eng. Trans. Jpn. J61-C, 248–255 (1978).

1977 (2)

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

U. Tulunay-Keesey and R. M. Jones, “Spatial sensitization as a function of delay,” Vision Res. 17, 1191–1199 (1977).
[Crossref] [PubMed]

1974 (1)

U. Tulunay-Keesey and A. Vassilev, “Foveal spatial sensitization with stabilized vision,” Vision Res. 14, 101–105 (1974).
[Crossref] [PubMed]

1973 (3)

In view of the large number of measurements that were planned, it was decided not to use the more time-consuming criterion-free procedures. There is some evidence to suggest that, although thresholds measured by method of adjustment may be somewhat higher than those measured by forced choice, the functional relations change little [D. H. Kelly and R. E. Savoie, “A study of sine wave contrast sensitivity by two psychophysical methods,” Percept. Psychopys. 14, 313–318 (1973)].
[Crossref]

S. Petry, D. C. Hood, and F. Goodkin, “Time course of lateral inhibition in the human visual system,” J. Opt. Soc. Am. 63, 385–386 (1973).
[Crossref] [PubMed]

A. Vassilev, “Contrast sensitivity near borders: significance of test stimulus form, size and duration,” Vision Res. 13, 719–730 (1973).
[Crossref] [PubMed]

1972 (1)

1970 (1)

C. Rashbass, “The visibility of transient changes of luminance,” J. Physiol. London 210, 165–186 (1970).

1969 (2)

C. Blakemore and F. W. Campbell, “On the existence of neurones in the human visual system selectively sensitive to the orientation and size of retinal images,” J. Physiol. London 203, 237–260 (1969).

F. W. Campbell, R. H. S. Carpenter, and J. Z. Levinson, “Visibility of a periodic patterns compared with that of sinusoidal gratings,” J. Physiol. London 204, 283–298 (1969).

1968 (1)

D. Y. Teller, “Increment thresholds on black bars,” Vision Res. 8, 713–718 (1968).
[Crossref] [PubMed]

1967 (3)

G. Westheimer, “Spatial interaction in human cone vision,” J. Physiol. London 190, 139–154 (1967).

S. Novak, “Invariance of detection thresholds across a light–dark boundary using dichoptic presentation,” J. Opt. Soc. Am. 57, 1059–1060 (1967).
[Crossref] [PubMed]

A. Fiorentini and M. T. Zoli, “Detection of a target superimposed to a step pattern of illumination,” Atti Fond. Giorgio Ronchi 22, 207–217 (1967).

1966 (3)

1963 (2)

S. Novak and G. Sperling, “Visual threshold near a continuously visible or a briefly presented light–dark boundary,” Opt. Acta 10, 187–191 (1963).
[Crossref]

H. R. Blackwell, “Neural theories of simple visual discriminations,” J. Opt. Soc. Am. 53, 129–160 (1963).
[Crossref] [PubMed]

1955 (1)

A. Fiorentini, M. Jeanne, and G. Toraldo di Francia, “Measurements of differential threshold in the presence of spatial illumination gradient,” Atti Fond. Giorgio Ronchi 10, 371–379 (1955).

1948 (1)

B. H. Crawford, “Visual adaptation in relation to brief conditioning stimuli,” Proc. R. Soc. London Ser. B 134, 283–302 (1948).
[Crossref]

Blackwell, H. R.

Blakemore, C.

C. Blakemore and F. W. Campbell, “On the existence of neurones in the human visual system selectively sensitive to the orientation and size of retinal images,” J. Physiol. London 203, 237–260 (1969).

Burkhardt, D. A.

Campbell, F. W.

C. Blakemore and F. W. Campbell, “On the existence of neurones in the human visual system selectively sensitive to the orientation and size of retinal images,” J. Physiol. London 203, 237–260 (1969).

F. W. Campbell, R. H. S. Carpenter, and J. Z. Levinson, “Visibility of a periodic patterns compared with that of sinusoidal gratings,” J. Physiol. London 204, 283–298 (1969).

Carpenter, R. H. S.

F. W. Campbell, R. H. S. Carpenter, and J. Z. Levinson, “Visibility of a periodic patterns compared with that of sinusoidal gratings,” J. Physiol. London 204, 283–298 (1969).

Crawford, B. H.

B. H. Crawford, “Visual adaptation in relation to brief conditioning stimuli,” Proc. R. Soc. London Ser. B 134, 283–302 (1948).
[Crossref]

Ditchburn, R. W.

R. W. Ditchburn, Eyemovements and Visual Perception (Clarendon, Oxford, 1973), pp. 84–85, Table 4.1.

Fiorentini, A.

A. Fiorentini and M. T. Zoli, “Detection of a target superimposed to a step pattern of illumination,” Atti Fond. Giorgio Ronchi 22, 207–217 (1967).

A. Fiorentini and M. T. Zoli, “Detection of a target superimposed to a step pattern of illumination,” Atti Fond. Giorgio Ronchi 21, 338–356 (1966).

A. Fiorentini, M. Jeanne, and G. Toraldo di Francia, “Measurements of differential threshold in the presence of spatial illumination gradient,” Atti Fond. Giorgio Ronchi 10, 371–379 (1955).

Furukawa, T.

S. Hagiwara and T. Furukawa, “Incremental and decremental thresholds on mach patterns,” Inst. Electron. Commun. Eng. Trans. Jpn. J61-C, 248–255 (1978).

Goodkin, F.

Hagiwara, S.

S. Hagiwara and T. Furukawa, “Incremental and decremental thresholds on mach patterns,” Inst. Electron. Commun. Eng. Trans. Jpn. J61-C, 248–255 (1978).

Hood, D. C.

Jeanne, M.

A. Fiorentini, M. Jeanne, and G. Toraldo di Francia, “Measurements of differential threshold in the presence of spatial illumination gradient,” Atti Fond. Giorgio Ronchi 10, 371–379 (1955).

Jones, R. M.

U. Tulunay-Keesey and R. M. Jones, “Spatial sensitization as a function of delay,” Vision Res. 17, 1191–1199 (1977).
[Crossref] [PubMed]

Julesz, B.

Kelly, D. H.

In view of the large number of measurements that were planned, it was decided not to use the more time-consuming criterion-free procedures. There is some evidence to suggest that, although thresholds measured by method of adjustment may be somewhat higher than those measured by forced choice, the functional relations change little [D. H. Kelly and R. E. Savoie, “A study of sine wave contrast sensitivity by two psychophysical methods,” Percept. Psychopys. 14, 313–318 (1973)].
[Crossref]

Krauskopf, J.

J. Krauskopf, “Discrimination and detection of changes in luminance,” Vision Res. 20, 671–677 (1980).
[Crossref] [PubMed]

Levinson, J. Z.

F. W. Campbell, R. H. S. Carpenter, and J. Z. Levinson, “Visibility of a periodic patterns compared with that of sinusoidal gratings,” J. Physiol. London 204, 283–298 (1969).

Limb, J. O.

F. X. J. Lukas, U. Tulunay-Keesey, and J. O. Limb, “Thresholds at luminance edges under stabilized viewing conditions,” J. Opt. Soc. Am. 70, 418–422 (1980).
[Crossref] [PubMed]

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

U. Tulunay-Keesey and J. O. Limb, “Eye movements during short intervals,” presented at Association for Research in Vision and Ophthalmology annual meeting, Sarasota, Florida, April 27, 1981.

Lukas, F. X. J.

Matthews, M. L.

Novak, S.

S. Novak, “Invariance of detection thresholds across a light–dark boundary using dichoptic presentation,” J. Opt. Soc. Am. 57, 1059–1060 (1967).
[Crossref] [PubMed]

S. Novak and G. Sperling, “Visual threshold near a continuously visible or a briefly presented light–dark boundary,” Opt. Acta 10, 187–191 (1963).
[Crossref]

Petry, S.

Rashbass, C.

C. Rashbass, “The visibility of transient changes of luminance,” J. Physiol. London 210, 165–186 (1970).

Rubinstein, C. B.

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

Savoie, R. E.

In view of the large number of measurements that were planned, it was decided not to use the more time-consuming criterion-free procedures. There is some evidence to suggest that, although thresholds measured by method of adjustment may be somewhat higher than those measured by forced choice, the functional relations change little [D. H. Kelly and R. E. Savoie, “A study of sine wave contrast sensitivity by two psychophysical methods,” Percept. Psychopys. 14, 313–318 (1973)].
[Crossref]

Sperling, G.

S. Novak and G. Sperling, “Visual threshold near a continuously visible or a briefly presented light–dark boundary,” Opt. Acta 10, 187–191 (1963).
[Crossref]

Stromeyer, C. F.

Teller, D. Y.

D. Y. Teller, “Increment thresholds on black bars,” Vision Res. 8, 713–718 (1968).
[Crossref] [PubMed]

Toraldo di Francia, G.

A. Fiorentini, M. Jeanne, and G. Toraldo di Francia, “Measurements of differential threshold in the presence of spatial illumination gradient,” Atti Fond. Giorgio Ronchi 10, 371–379 (1955).

Tulunay-Keesey, U.

F. X. J. Lukas, U. Tulunay-Keesey, and J. O. Limb, “Thresholds at luminance edges under stabilized viewing conditions,” J. Opt. Soc. Am. 70, 418–422 (1980).
[Crossref] [PubMed]

U. Tulunay-Keesey and R. M. Jones, “Spatial sensitization as a function of delay,” Vision Res. 17, 1191–1199 (1977).
[Crossref] [PubMed]

U. Tulunay-Keesey and A. Vassilev, “Foveal spatial sensitization with stabilized vision,” Vision Res. 14, 101–105 (1974).
[Crossref] [PubMed]

U. Tulunay-Keesey and J. O. Limb, “Eye movements during short intervals,” presented at Association for Research in Vision and Ophthalmology annual meeting, Sarasota, Florida, April 27, 1981.

Vassilev, A.

U. Tulunay-Keesey and A. Vassilev, “Foveal spatial sensitization with stabilized vision,” Vision Res. 14, 101–105 (1974).
[Crossref] [PubMed]

A. Vassilev, “Contrast sensitivity near borders: significance of test stimulus form, size and duration,” Vision Res. 13, 719–730 (1973).
[Crossref] [PubMed]

Westheimer, G.

G. Westheimer, “Spatial interaction in human cone vision,” J. Physiol. London 190, 139–154 (1967).

Zoli, M. T.

A. Fiorentini and M. T. Zoli, “Detection of a target superimposed to a step pattern of illumination,” Atti Fond. Giorgio Ronchi 22, 207–217 (1967).

A. Fiorentini and M. T. Zoli, “Detection of a target superimposed to a step pattern of illumination,” Atti Fond. Giorgio Ronchi 21, 338–356 (1966).

Atti Fond. Giorgio Ronchi (3)

A. Fiorentini, M. Jeanne, and G. Toraldo di Francia, “Measurements of differential threshold in the presence of spatial illumination gradient,” Atti Fond. Giorgio Ronchi 10, 371–379 (1955).

A. Fiorentini and M. T. Zoli, “Detection of a target superimposed to a step pattern of illumination,” Atti Fond. Giorgio Ronchi 21, 338–356 (1966).

A. Fiorentini and M. T. Zoli, “Detection of a target superimposed to a step pattern of illumination,” Atti Fond. Giorgio Ronchi 22, 207–217 (1967).

Inst. Electron. Commun. Eng. Trans. Jpn. (1)

S. Hagiwara and T. Furukawa, “Incremental and decremental thresholds on mach patterns,” Inst. Electron. Commun. Eng. Trans. Jpn. J61-C, 248–255 (1978).

J. Opt. Soc. Am. (7)

J. Physiol. London (4)

C. Blakemore and F. W. Campbell, “On the existence of neurones in the human visual system selectively sensitive to the orientation and size of retinal images,” J. Physiol. London 203, 237–260 (1969).

G. Westheimer, “Spatial interaction in human cone vision,” J. Physiol. London 190, 139–154 (1967).

F. W. Campbell, R. H. S. Carpenter, and J. Z. Levinson, “Visibility of a periodic patterns compared with that of sinusoidal gratings,” J. Physiol. London 204, 283–298 (1969).

C. Rashbass, “The visibility of transient changes of luminance,” J. Physiol. London 210, 165–186 (1970).

Opt. Acta (1)

S. Novak and G. Sperling, “Visual threshold near a continuously visible or a briefly presented light–dark boundary,” Opt. Acta 10, 187–191 (1963).
[Crossref]

Percept. Psychopys. (1)

In view of the large number of measurements that were planned, it was decided not to use the more time-consuming criterion-free procedures. There is some evidence to suggest that, although thresholds measured by method of adjustment may be somewhat higher than those measured by forced choice, the functional relations change little [D. H. Kelly and R. E. Savoie, “A study of sine wave contrast sensitivity by two psychophysical methods,” Percept. Psychopys. 14, 313–318 (1973)].
[Crossref]

Proc. R. Soc. London Ser. B (1)

B. H. Crawford, “Visual adaptation in relation to brief conditioning stimuli,” Proc. R. Soc. London Ser. B 134, 283–302 (1948).
[Crossref]

Vision Res. (6)

J. Krauskopf, “Discrimination and detection of changes in luminance,” Vision Res. 20, 671–677 (1980).
[Crossref] [PubMed]

U. Tulunay-Keesey and R. M. Jones, “Spatial sensitization as a function of delay,” Vision Res. 17, 1191–1199 (1977).
[Crossref] [PubMed]

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

D. Y. Teller, “Increment thresholds on black bars,” Vision Res. 8, 713–718 (1968).
[Crossref] [PubMed]

U. Tulunay-Keesey and A. Vassilev, “Foveal spatial sensitization with stabilized vision,” Vision Res. 14, 101–105 (1974).
[Crossref] [PubMed]

A. Vassilev, “Contrast sensitivity near borders: significance of test stimulus form, size and duration,” Vision Res. 13, 719–730 (1973).
[Crossref] [PubMed]

Other (3)

R. W. Ditchburn, Eyemovements and Visual Perception (Clarendon, Oxford, 1973), pp. 84–85, Table 4.1.

U. Tulunay-Keesey and J. O. Limb, “Eye movements during short intervals,” presented at Association for Research in Vision and Ophthalmology annual meeting, Sarasota, Florida, April 27, 1981.

We attempted to create a spatial analogue of Krauskopf’s temporal experiment.20 The threshold for light or dark target lines was measured as before but on a plain background. Between presentations of the target, the subject viewed a set of highly visible, 1-min-wide, dark lines spaced 20 min apart. This was an attempt to modify the dark threshold selectively. Adapting to this grid of lines did not change the visibility of the light and dark target lines relative to each other or to their visibility in the unadapted condition.

Cited By

OSA participates in Crossref's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (22)

Fig. 1
Fig. 1

Display seen by the subjects.

Fig. 2
Fig. 2

Spatiotemporal configuration for four types of presentations. (a) Static edge, (b) impulse edge with fixed background, (c) impulse edge with transient background, and (d) step edge with fixed background.

Fig. 3
Fig. 3

Temporal sequence of events within a trial.

Fig. 4
Fig. 4

Comparison of increment and decrement thresholds on the light side of a continuously presented (static) edge for two subjects. Solid line, light threshold; dashed line, dark threshold.

Fig. 5
Fig. 5

Increment threshold on the dark side of a continuously presented (static) edge for both fovea and periphery. Solid line, fovea; dashed line, periphery.

Fig. 6
Fig. 6

Increment threshold on the light side of a briefly presented (impulse) edge for the fixed-background condition for three different asynchronies. Solid line, 0 msec; long-dashed line, 50 msec; short-dashed line, 200 msec. The error bars on the upper panel for 0-msec asynchrony indicate ±3 standard errors.

Fig. 7
Fig. 7

Comparison of the effect of fixed and transient backgrounds on the increment threshold measured on the light side of an edge. Top panel, fixed background; bottom panel, transient background. Asynchronies are full line, 0 msec; long-dashed line, 50 msec; short-dashed line, 200 msec.

Fig. 8
Fig. 8

Increment and decrement thresholds measured on the light side of a briefly presented edge for the fixed-background condition. Asynchrony is 0 msec. Solid line, increment threshold; dashed line, decrement threshold. The error bars indicate ±3 standard errors.

Fig. 9
Fig. 9

Comparison of increment and decrement threshold measured on the light and dark sides of a briefly presented edge. In all cases the fixed-background condition was used. Asynchrony is 0 msec. In order to measure negative thresholds, the dark side of the edge (lower-right-hand panel) was increased in luminance from 1 to 5 fL. The light side was increased from 10 to 20 fL.

Fig. 10
Fig. 10

Increment threshold measured on the light side of a briefly presented edge for the transient-background condition. Asynchrony is 0 msec.

Fig. 11
Fig. 11

The temporal course of both increment and decrement thresholds measured on the light side of a briefly presented edge with fixed background. Spatial position, 0.5 min from the edge. Solid line, increment threshod; dashed line, decrement threshold.

Fig. 12
Fig. 12

Temporal course of increment threshold on the light side of a briefly presented edge for the transent-background condition. Spatial position 1 min from the edge.

Fig. 13
Fig. 13

Comparison of the temporal course of the increment threshold at two different spatial positions measured on the light side of a briefly presented edge with fixed background. Solid line, 0.5 min from edge; dashed line, 2 min from edge.

Fig. 14
Fig. 14

Same as Fig 13 except that measurements are for decrement instead of increment threshold.

Fig. 15
Fig. 15

Comparison of spatial change in increment threshold at three different asynchronies measured on the light side of a briefly presented edge for the fixed-background condition. Short-dashed line, −16 msec; solid line, 0 msec; long-dashed line, 16 msec. The error bars indicate ±3 standard errors.

Fig. 16
Fig. 16

Comparison of the effect of temporal transient versus spatiotemporal transient. The spatiotemporal transient was generated by measuring the increment threshold 1 min from the briefly presented edge on the light side for the transient background. For the temporal transient, the edge was moved 100 min from the target. Solid line, spatiotemporal transient; dashed line, temporal transient.

Fig. 17
Fig. 17

Increment threshold adjacent to a briefly presented edge for the fixed-background condition. Measurements taken 500 min in the periphery; asynchronies are solid line, 0 msec; long-dashed line, 50 msec; and short-dashed line, 200 msec.

Fig. 18
Fig. 18

Increment threshold adjacent to a briefly presented edge measured on the dark side of an edge for the fixed-background condition measured 500 min in the periphery. Asynchronies are solid line, 0 msec; long-dashed line, 50 msec; and short-dashed line, 200 msec. The zero asynchrony data were recorded in two separate session types indicated by the filled and open circles.

Fig. 19
Fig. 19

Temporal course of the increment and decrement threshold measured adjacent to a step edge for the fixed-background condition. For the increment threshold, the target was 1 min from the edge. For the decrement threshold, the target was 4 min from the edge.

Fig. 20
Fig. 20

Explanation of a receptive-field model of the edge effect for a target on a fixed background (see text).

Fig. 21
Fig. 21

Explanation of a receptive-field model of the edge effect for a target on a transient background (see text).

Fig. 22
Fig. 22

Comparison of increment threshold for a step edge (dashed line) with the integrated response of an impulse edge (solid line). For the step edge, the target was located 1 min from the edge; for the impulse edge, the target was 0.5 min from the edge.