Abstract

It is well known that adjacent contours can reduce the visual acuity of single letters. Although this has traditionally been considered only in terms of a neural-based interaction, it has recently been suggested that the information content in the stimulus may account for the interaction. Here we ask the question, “Do similar interference effects occur for the discrimination of low-contrast letters whose size is larger than that corresponding to the resolution limit?” If so, previous acuity-based interaction results may be of more general importance. We show that while there are interference effects of nearby contours, they are of a form different from that observed at the resolution limit. In particular, the contrast polarity of the nearby contour is unimportant, which in turn suggests that a physical explanation is inappropriate. Also, the discrimination of an easily resolvable, unflanked Landolt C target requires information over a much wider spatial-frequency range than its counterpart at the resolution limit.

© 2001 Optical Society of America

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References

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  1. M. C. Flom, G. Heath, E. Takahashi, “Crowding interaction and visual resolution: Contralateral effects,” Science 142, 979–980 (1963).
    [CrossRef] [PubMed]
  2. M. C. Flom, F. W. Weymouth, D. Kahneman, “Visual resolution and contour interaction,” J. Opt. Soc. Am. 53, 1026–1032 (1963).
    [CrossRef] [PubMed]
  3. M. C. Flom, “Contour interaction and the crowding effect,” Probl. Optom. 3, 237–257 (1991).
  4. W. K. Estes, D. H. Allmeyer, S. M. Reder, “Serial position functions for letter identification at brief and extended exposure periods,” Percept. Psychophys. 19, 1–15 (1976).
    [CrossRef]
  5. A. J. Simmers, L. S. Gray, P. V. McGraw, B. Winn, “Contour interaction for high and low contrast optotypes in normal and amblyopic observers,” Ophthalmic Physiol. Opt. 19, 253–260 (1999).
    [CrossRef]
  6. J. Wagner, “Experimentelle Beitrage zur Psychologie des lesens,” Z. Psychol. 80, 1–75 (1918).
  7. H. Strasburger, L. O. Harvey, I. Rentschler, “Contrast thresholds for the identification of numeric charters in direct and eccentric view,” Percept. Psychophys. 49, 495–508 (1991).
    [CrossRef] [PubMed]
  8. C. D. Gilbert, T. N. Wiesel, “Columnar specificity of intrinsic horizontal and corticocortical connections in cat visual cortex,” J. Neurosci. 9, 2432–2442 (1989).
    [PubMed]
  9. D. Y. T’so, C. D. Gilbert, “The organization of chromatic and spatial interactions in the primate striate cortex,” J. Neurosci. 8, 1712–1727 (1988).
  10. R. F. Hess, S. C. Dakin, N. Kapoor, “Foveal contour interaction: physics or physiology?” Vision Res. 20, 365–370 (2000).
    [CrossRef]
  11. D. H. Brainard, “The Psychophysics Toolbox,” Spatial Vision 10, 433–446 (1997).
    [CrossRef] [PubMed]
  12. J. Solomon, D. Pelli, “The visual filter mediating letter identification,” Nature (London) 369, 395–397 (1994).
    [CrossRef]
  13. S. T. L. Chung, G. E. Legge, “Spatial frequency dependence of letter recognition in central and peripheral vision,” Invest. Ophthalmol. Visual Sci. Suppl. 38, S639 (1997).
  14. M. Palomares, C. LaPutt, D. Pelli, “Crowding is unlike ordinary masking,” Invest. Ophthalmol. Visual Sci. Suppl. 40, S351 (1999).
  15. D. Pelli, M. Palomares, “The role of feature detection in crowding,” Invest. Ophthalmol. Visual Sci. Suppl. 41, S37 (2000).

2000

R. F. Hess, S. C. Dakin, N. Kapoor, “Foveal contour interaction: physics or physiology?” Vision Res. 20, 365–370 (2000).
[CrossRef]

D. Pelli, M. Palomares, “The role of feature detection in crowding,” Invest. Ophthalmol. Visual Sci. Suppl. 41, S37 (2000).

1999

M. Palomares, C. LaPutt, D. Pelli, “Crowding is unlike ordinary masking,” Invest. Ophthalmol. Visual Sci. Suppl. 40, S351 (1999).

A. J. Simmers, L. S. Gray, P. V. McGraw, B. Winn, “Contour interaction for high and low contrast optotypes in normal and amblyopic observers,” Ophthalmic Physiol. Opt. 19, 253–260 (1999).
[CrossRef]

1997

D. H. Brainard, “The Psychophysics Toolbox,” Spatial Vision 10, 433–446 (1997).
[CrossRef] [PubMed]

S. T. L. Chung, G. E. Legge, “Spatial frequency dependence of letter recognition in central and peripheral vision,” Invest. Ophthalmol. Visual Sci. Suppl. 38, S639 (1997).

1994

J. Solomon, D. Pelli, “The visual filter mediating letter identification,” Nature (London) 369, 395–397 (1994).
[CrossRef]

1991

H. Strasburger, L. O. Harvey, I. Rentschler, “Contrast thresholds for the identification of numeric charters in direct and eccentric view,” Percept. Psychophys. 49, 495–508 (1991).
[CrossRef] [PubMed]

M. C. Flom, “Contour interaction and the crowding effect,” Probl. Optom. 3, 237–257 (1991).

1989

C. D. Gilbert, T. N. Wiesel, “Columnar specificity of intrinsic horizontal and corticocortical connections in cat visual cortex,” J. Neurosci. 9, 2432–2442 (1989).
[PubMed]

1988

D. Y. T’so, C. D. Gilbert, “The organization of chromatic and spatial interactions in the primate striate cortex,” J. Neurosci. 8, 1712–1727 (1988).

1976

W. K. Estes, D. H. Allmeyer, S. M. Reder, “Serial position functions for letter identification at brief and extended exposure periods,” Percept. Psychophys. 19, 1–15 (1976).
[CrossRef]

1963

M. C. Flom, G. Heath, E. Takahashi, “Crowding interaction and visual resolution: Contralateral effects,” Science 142, 979–980 (1963).
[CrossRef] [PubMed]

M. C. Flom, F. W. Weymouth, D. Kahneman, “Visual resolution and contour interaction,” J. Opt. Soc. Am. 53, 1026–1032 (1963).
[CrossRef] [PubMed]

1918

J. Wagner, “Experimentelle Beitrage zur Psychologie des lesens,” Z. Psychol. 80, 1–75 (1918).

Allmeyer, D. H.

W. K. Estes, D. H. Allmeyer, S. M. Reder, “Serial position functions for letter identification at brief and extended exposure periods,” Percept. Psychophys. 19, 1–15 (1976).
[CrossRef]

Brainard, D. H.

D. H. Brainard, “The Psychophysics Toolbox,” Spatial Vision 10, 433–446 (1997).
[CrossRef] [PubMed]

Chung, S. T. L.

S. T. L. Chung, G. E. Legge, “Spatial frequency dependence of letter recognition in central and peripheral vision,” Invest. Ophthalmol. Visual Sci. Suppl. 38, S639 (1997).

Dakin, S. C.

R. F. Hess, S. C. Dakin, N. Kapoor, “Foveal contour interaction: physics or physiology?” Vision Res. 20, 365–370 (2000).
[CrossRef]

Estes, W. K.

W. K. Estes, D. H. Allmeyer, S. M. Reder, “Serial position functions for letter identification at brief and extended exposure periods,” Percept. Psychophys. 19, 1–15 (1976).
[CrossRef]

Flom, M. C.

M. C. Flom, “Contour interaction and the crowding effect,” Probl. Optom. 3, 237–257 (1991).

M. C. Flom, G. Heath, E. Takahashi, “Crowding interaction and visual resolution: Contralateral effects,” Science 142, 979–980 (1963).
[CrossRef] [PubMed]

M. C. Flom, F. W. Weymouth, D. Kahneman, “Visual resolution and contour interaction,” J. Opt. Soc. Am. 53, 1026–1032 (1963).
[CrossRef] [PubMed]

Gilbert, C. D.

C. D. Gilbert, T. N. Wiesel, “Columnar specificity of intrinsic horizontal and corticocortical connections in cat visual cortex,” J. Neurosci. 9, 2432–2442 (1989).
[PubMed]

D. Y. T’so, C. D. Gilbert, “The organization of chromatic and spatial interactions in the primate striate cortex,” J. Neurosci. 8, 1712–1727 (1988).

Gray, L. S.

A. J. Simmers, L. S. Gray, P. V. McGraw, B. Winn, “Contour interaction for high and low contrast optotypes in normal and amblyopic observers,” Ophthalmic Physiol. Opt. 19, 253–260 (1999).
[CrossRef]

Harvey, L. O.

H. Strasburger, L. O. Harvey, I. Rentschler, “Contrast thresholds for the identification of numeric charters in direct and eccentric view,” Percept. Psychophys. 49, 495–508 (1991).
[CrossRef] [PubMed]

Heath, G.

M. C. Flom, G. Heath, E. Takahashi, “Crowding interaction and visual resolution: Contralateral effects,” Science 142, 979–980 (1963).
[CrossRef] [PubMed]

Hess, R. F.

R. F. Hess, S. C. Dakin, N. Kapoor, “Foveal contour interaction: physics or physiology?” Vision Res. 20, 365–370 (2000).
[CrossRef]

Kahneman, D.

Kapoor, N.

R. F. Hess, S. C. Dakin, N. Kapoor, “Foveal contour interaction: physics or physiology?” Vision Res. 20, 365–370 (2000).
[CrossRef]

LaPutt, C.

M. Palomares, C. LaPutt, D. Pelli, “Crowding is unlike ordinary masking,” Invest. Ophthalmol. Visual Sci. Suppl. 40, S351 (1999).

Legge, G. E.

S. T. L. Chung, G. E. Legge, “Spatial frequency dependence of letter recognition in central and peripheral vision,” Invest. Ophthalmol. Visual Sci. Suppl. 38, S639 (1997).

McGraw, P. V.

A. J. Simmers, L. S. Gray, P. V. McGraw, B. Winn, “Contour interaction for high and low contrast optotypes in normal and amblyopic observers,” Ophthalmic Physiol. Opt. 19, 253–260 (1999).
[CrossRef]

Palomares, M.

D. Pelli, M. Palomares, “The role of feature detection in crowding,” Invest. Ophthalmol. Visual Sci. Suppl. 41, S37 (2000).

M. Palomares, C. LaPutt, D. Pelli, “Crowding is unlike ordinary masking,” Invest. Ophthalmol. Visual Sci. Suppl. 40, S351 (1999).

Pelli, D.

D. Pelli, M. Palomares, “The role of feature detection in crowding,” Invest. Ophthalmol. Visual Sci. Suppl. 41, S37 (2000).

M. Palomares, C. LaPutt, D. Pelli, “Crowding is unlike ordinary masking,” Invest. Ophthalmol. Visual Sci. Suppl. 40, S351 (1999).

J. Solomon, D. Pelli, “The visual filter mediating letter identification,” Nature (London) 369, 395–397 (1994).
[CrossRef]

Reder, S. M.

W. K. Estes, D. H. Allmeyer, S. M. Reder, “Serial position functions for letter identification at brief and extended exposure periods,” Percept. Psychophys. 19, 1–15 (1976).
[CrossRef]

Rentschler, I.

H. Strasburger, L. O. Harvey, I. Rentschler, “Contrast thresholds for the identification of numeric charters in direct and eccentric view,” Percept. Psychophys. 49, 495–508 (1991).
[CrossRef] [PubMed]

Simmers, A. J.

A. J. Simmers, L. S. Gray, P. V. McGraw, B. Winn, “Contour interaction for high and low contrast optotypes in normal and amblyopic observers,” Ophthalmic Physiol. Opt. 19, 253–260 (1999).
[CrossRef]

Solomon, J.

J. Solomon, D. Pelli, “The visual filter mediating letter identification,” Nature (London) 369, 395–397 (1994).
[CrossRef]

Strasburger, H.

H. Strasburger, L. O. Harvey, I. Rentschler, “Contrast thresholds for the identification of numeric charters in direct and eccentric view,” Percept. Psychophys. 49, 495–508 (1991).
[CrossRef] [PubMed]

T’so, D. Y.

D. Y. T’so, C. D. Gilbert, “The organization of chromatic and spatial interactions in the primate striate cortex,” J. Neurosci. 8, 1712–1727 (1988).

Takahashi, E.

M. C. Flom, G. Heath, E. Takahashi, “Crowding interaction and visual resolution: Contralateral effects,” Science 142, 979–980 (1963).
[CrossRef] [PubMed]

Wagner, J.

J. Wagner, “Experimentelle Beitrage zur Psychologie des lesens,” Z. Psychol. 80, 1–75 (1918).

Weymouth, F. W.

Wiesel, T. N.

C. D. Gilbert, T. N. Wiesel, “Columnar specificity of intrinsic horizontal and corticocortical connections in cat visual cortex,” J. Neurosci. 9, 2432–2442 (1989).
[PubMed]

Winn, B.

A. J. Simmers, L. S. Gray, P. V. McGraw, B. Winn, “Contour interaction for high and low contrast optotypes in normal and amblyopic observers,” Ophthalmic Physiol. Opt. 19, 253–260 (1999).
[CrossRef]

Invest. Ophthalmol. Visual Sci. Suppl.

S. T. L. Chung, G. E. Legge, “Spatial frequency dependence of letter recognition in central and peripheral vision,” Invest. Ophthalmol. Visual Sci. Suppl. 38, S639 (1997).

M. Palomares, C. LaPutt, D. Pelli, “Crowding is unlike ordinary masking,” Invest. Ophthalmol. Visual Sci. Suppl. 40, S351 (1999).

D. Pelli, M. Palomares, “The role of feature detection in crowding,” Invest. Ophthalmol. Visual Sci. Suppl. 41, S37 (2000).

J. Neurosci.

C. D. Gilbert, T. N. Wiesel, “Columnar specificity of intrinsic horizontal and corticocortical connections in cat visual cortex,” J. Neurosci. 9, 2432–2442 (1989).
[PubMed]

D. Y. T’so, C. D. Gilbert, “The organization of chromatic and spatial interactions in the primate striate cortex,” J. Neurosci. 8, 1712–1727 (1988).

J. Opt. Soc. Am.

Nature (London)

J. Solomon, D. Pelli, “The visual filter mediating letter identification,” Nature (London) 369, 395–397 (1994).
[CrossRef]

Ophthalmic Physiol. Opt.

A. J. Simmers, L. S. Gray, P. V. McGraw, B. Winn, “Contour interaction for high and low contrast optotypes in normal and amblyopic observers,” Ophthalmic Physiol. Opt. 19, 253–260 (1999).
[CrossRef]

Percept. Psychophys.

W. K. Estes, D. H. Allmeyer, S. M. Reder, “Serial position functions for letter identification at brief and extended exposure periods,” Percept. Psychophys. 19, 1–15 (1976).
[CrossRef]

H. Strasburger, L. O. Harvey, I. Rentschler, “Contrast thresholds for the identification of numeric charters in direct and eccentric view,” Percept. Psychophys. 49, 495–508 (1991).
[CrossRef] [PubMed]

Probl. Optom.

M. C. Flom, “Contour interaction and the crowding effect,” Probl. Optom. 3, 237–257 (1991).

Science

M. C. Flom, G. Heath, E. Takahashi, “Crowding interaction and visual resolution: Contralateral effects,” Science 142, 979–980 (1963).
[CrossRef] [PubMed]

Spatial Vision

D. H. Brainard, “The Psychophysics Toolbox,” Spatial Vision 10, 433–446 (1997).
[CrossRef] [PubMed]

Vision Res.

R. F. Hess, S. C. Dakin, N. Kapoor, “Foveal contour interaction: physics or physiology?” Vision Res. 20, 365–370 (2000).
[CrossRef]

Z. Psychol.

J. Wagner, “Experimentelle Beitrage zur Psychologie des lesens,” Z. Psychol. 80, 1–75 (1918).

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Figures (5)

Fig. 1
Fig. 1

Examples of the stimuli used. A, Low-contrast Landolt C with no flanking bars. B, Low-contrast Landolt C with flanking bars of the same polarity, separated by two bar widths. C, Low-contrast Landolt C with flanking bars of the opposite polarity, separated by one bar width.

Fig. 2
Fig. 2

Discrimination of the position of the gap in a Landolt C (without flanking bars) as a function of filter peak spatial frequency (full bandwidth at half-height was 1.6 octaves). Solid symbols plot percent correct for two subjects against filter peak spatial frequency (LoG filter) for discrimination of the low-contrast, easily resolvable Landolt C (angular subtense of C was 0.6°; n=300; error bars plot the standard deviation estimated from the normal approximation to the mean). Open symbols plot previous data (average for two subjects) for the Landolt C at the acuity limit (determined for each subject). Spatial frequencies are plotted in cycles per letter.

Fig. 3
Fig. 3

Discrimination of the position of the gap in a low-contrast (3% for CW and 5% for RH) Landolt C (without flanking bars) as a function of filter bandwidth (linear, ideal filter) for three center frequencies of the filter, for two subjects. The horizontal dashed lines represent either the performance level for detecting an unfiltered version of the stimulus. Regardless of the filter position, for performance similar to that in the unfiltered case, filter bandwidths in excess of 2 octaves are required. Spatial frequencies are plotted in cycles per letter. n=300; error bars plot standard deviations.

Fig. 4
Fig. 4

Discrimination of the position of the gap in a Landolt C as a function of separation of the flanking bars (in bar widths). Each graph shows data for one subject with open symbols for bars of the same polarity and solid symbols for bars of the opposite polarity. n=400; error bars plot standard deviations.

Fig. 5
Fig. 5

Discrimination of the orientation of a Landolt C (with and without flanking bars) as a function of filter peak spatial frequency (LoG filter, BW 1.6 octaves). Open symbols plot data obtained with no flanking bars; solid symbols plot data obtained with three bar separations (in bar widths, bars of same contrast polarity). The data obtained with flanking bars were fitted with log-Gaussian functions by use of a maximum-likelihood technique; the dashed curves show these fits. Spatial frequencies are plotted in cycles per letter. n=300; error bars plot standard deviations.

Equations (1)

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2G(x,y)=1-x2+y22σ2 expx2+y22σ2.

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