Abstract

Using the scanned text technique developed by Legge and his colleagues, the present study demonstrates that visually normal subjects can read with the isolated rod visual system. The subjects were able to read text (albeit slowly) at luminances near their absolute thresholds. The peak reading rates increase with luminance at about 40 words per minute for every tenfold increase in luminance. The authors suggest that the study of scotopic reading performance in normal subjects might contribute to an understanding of reading problems in patients with bilateral central scotoma.

© 1989 Optical Society of America

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References

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  1. Committee on Vision: Working Group on Night Vision. Symposium on Night Vision (National Academy Press, Washington DC, 1987).
  2. F. A. Geldard, Human Senses (Wiley, New York, 1953).
  3. G. T. Timberlake, E. Peli, E. A. Essock, R. A. Augliere, “Reading with a Macular Scotoma. II. Retinal Locus for Scanning Text,” Invest. Ophthalmol. Vis. Sci. 28, 1268 (1987).
    [PubMed]
  4. R. M. Steinman, R. J. Cuntiz, “Fixation of Targets Near the Absolute Foveal Threshold,” Vision Res. 8, 277 (1968).
    [CrossRef] [PubMed]
  5. H. R. Blackwell, O. M. Blackwell, “Rod and Cone Receptor Mechanisms in Typical and Atypical Congenital Achromatopsia,” Vision Res. 1, 62 (1961).
    [CrossRef]
  6. J. M. Daitch, D. G. Green, “Contrast Sensitivity of the Human Peripheral Retina,” Vision Res. 9, 947 (1969).
    [CrossRef] [PubMed]
  7. S. Hecht, S. Shlaer, “Intermittent Stimulation by Light. V. The Relation Between Intensity and Critical Frequency for Different Parts of the Spectrum,” J. Gen. Physiol. 19, 965 (1936).
    [CrossRef] [PubMed]
  8. D. A. Owens, “The Resting State of the Eyes,” Sci. Am. 72, 378 (1984).
  9. G. E. Legge, G. S. Rubin, “Psychophysics of Reading. IV. Wavelength Effects in Normal and Low Vision,” J. Opt. Soc. Am. A 3, 40 (1986).
    [CrossRef] [PubMed]
  10. G. E. Legge, D. G. Pelli, G. S. Rubin, M. M. Schleske, “Psychophysics of Reading—I. Normal Vision,” Vision Res. 25, 239 (1985).
    [CrossRef] [PubMed]
  11. G. E. Legge, G. S. Rubin, D. G. Pelli, M. M. Schleske, “Psychophysics of Reading—II. Low Vision,” Vision Res. 25, 253 (1985).
    [CrossRef] [PubMed]
  12. R. S. L. Young, J. Price, J. Harrison, “Psychophysical Study of Rod Adaptation in Patients with Congenital Stationary Night Blindness,” Clin. Vision Sci. 1, 137 (1987).

1987

G. T. Timberlake, E. Peli, E. A. Essock, R. A. Augliere, “Reading with a Macular Scotoma. II. Retinal Locus for Scanning Text,” Invest. Ophthalmol. Vis. Sci. 28, 1268 (1987).
[PubMed]

R. S. L. Young, J. Price, J. Harrison, “Psychophysical Study of Rod Adaptation in Patients with Congenital Stationary Night Blindness,” Clin. Vision Sci. 1, 137 (1987).

1986

1985

G. E. Legge, D. G. Pelli, G. S. Rubin, M. M. Schleske, “Psychophysics of Reading—I. Normal Vision,” Vision Res. 25, 239 (1985).
[CrossRef] [PubMed]

G. E. Legge, G. S. Rubin, D. G. Pelli, M. M. Schleske, “Psychophysics of Reading—II. Low Vision,” Vision Res. 25, 253 (1985).
[CrossRef] [PubMed]

1984

D. A. Owens, “The Resting State of the Eyes,” Sci. Am. 72, 378 (1984).

1969

J. M. Daitch, D. G. Green, “Contrast Sensitivity of the Human Peripheral Retina,” Vision Res. 9, 947 (1969).
[CrossRef] [PubMed]

1968

R. M. Steinman, R. J. Cuntiz, “Fixation of Targets Near the Absolute Foveal Threshold,” Vision Res. 8, 277 (1968).
[CrossRef] [PubMed]

1961

H. R. Blackwell, O. M. Blackwell, “Rod and Cone Receptor Mechanisms in Typical and Atypical Congenital Achromatopsia,” Vision Res. 1, 62 (1961).
[CrossRef]

1936

S. Hecht, S. Shlaer, “Intermittent Stimulation by Light. V. The Relation Between Intensity and Critical Frequency for Different Parts of the Spectrum,” J. Gen. Physiol. 19, 965 (1936).
[CrossRef] [PubMed]

Augliere, R. A.

G. T. Timberlake, E. Peli, E. A. Essock, R. A. Augliere, “Reading with a Macular Scotoma. II. Retinal Locus for Scanning Text,” Invest. Ophthalmol. Vis. Sci. 28, 1268 (1987).
[PubMed]

Blackwell, H. R.

H. R. Blackwell, O. M. Blackwell, “Rod and Cone Receptor Mechanisms in Typical and Atypical Congenital Achromatopsia,” Vision Res. 1, 62 (1961).
[CrossRef]

Blackwell, O. M.

H. R. Blackwell, O. M. Blackwell, “Rod and Cone Receptor Mechanisms in Typical and Atypical Congenital Achromatopsia,” Vision Res. 1, 62 (1961).
[CrossRef]

Cuntiz, R. J.

R. M. Steinman, R. J. Cuntiz, “Fixation of Targets Near the Absolute Foveal Threshold,” Vision Res. 8, 277 (1968).
[CrossRef] [PubMed]

Daitch, J. M.

J. M. Daitch, D. G. Green, “Contrast Sensitivity of the Human Peripheral Retina,” Vision Res. 9, 947 (1969).
[CrossRef] [PubMed]

Essock, E. A.

G. T. Timberlake, E. Peli, E. A. Essock, R. A. Augliere, “Reading with a Macular Scotoma. II. Retinal Locus for Scanning Text,” Invest. Ophthalmol. Vis. Sci. 28, 1268 (1987).
[PubMed]

Geldard, F. A.

F. A. Geldard, Human Senses (Wiley, New York, 1953).

Green, D. G.

J. M. Daitch, D. G. Green, “Contrast Sensitivity of the Human Peripheral Retina,” Vision Res. 9, 947 (1969).
[CrossRef] [PubMed]

Harrison, J.

R. S. L. Young, J. Price, J. Harrison, “Psychophysical Study of Rod Adaptation in Patients with Congenital Stationary Night Blindness,” Clin. Vision Sci. 1, 137 (1987).

Hecht, S.

S. Hecht, S. Shlaer, “Intermittent Stimulation by Light. V. The Relation Between Intensity and Critical Frequency for Different Parts of the Spectrum,” J. Gen. Physiol. 19, 965 (1936).
[CrossRef] [PubMed]

Legge, G. E.

G. E. Legge, G. S. Rubin, “Psychophysics of Reading. IV. Wavelength Effects in Normal and Low Vision,” J. Opt. Soc. Am. A 3, 40 (1986).
[CrossRef] [PubMed]

G. E. Legge, G. S. Rubin, D. G. Pelli, M. M. Schleske, “Psychophysics of Reading—II. Low Vision,” Vision Res. 25, 253 (1985).
[CrossRef] [PubMed]

G. E. Legge, D. G. Pelli, G. S. Rubin, M. M. Schleske, “Psychophysics of Reading—I. Normal Vision,” Vision Res. 25, 239 (1985).
[CrossRef] [PubMed]

Owens, D. A.

D. A. Owens, “The Resting State of the Eyes,” Sci. Am. 72, 378 (1984).

Peli, E.

G. T. Timberlake, E. Peli, E. A. Essock, R. A. Augliere, “Reading with a Macular Scotoma. II. Retinal Locus for Scanning Text,” Invest. Ophthalmol. Vis. Sci. 28, 1268 (1987).
[PubMed]

Pelli, D. G.

G. E. Legge, D. G. Pelli, G. S. Rubin, M. M. Schleske, “Psychophysics of Reading—I. Normal Vision,” Vision Res. 25, 239 (1985).
[CrossRef] [PubMed]

G. E. Legge, G. S. Rubin, D. G. Pelli, M. M. Schleske, “Psychophysics of Reading—II. Low Vision,” Vision Res. 25, 253 (1985).
[CrossRef] [PubMed]

Price, J.

R. S. L. Young, J. Price, J. Harrison, “Psychophysical Study of Rod Adaptation in Patients with Congenital Stationary Night Blindness,” Clin. Vision Sci. 1, 137 (1987).

Rubin, G. S.

G. E. Legge, G. S. Rubin, “Psychophysics of Reading. IV. Wavelength Effects in Normal and Low Vision,” J. Opt. Soc. Am. A 3, 40 (1986).
[CrossRef] [PubMed]

G. E. Legge, G. S. Rubin, D. G. Pelli, M. M. Schleske, “Psychophysics of Reading—II. Low Vision,” Vision Res. 25, 253 (1985).
[CrossRef] [PubMed]

G. E. Legge, D. G. Pelli, G. S. Rubin, M. M. Schleske, “Psychophysics of Reading—I. Normal Vision,” Vision Res. 25, 239 (1985).
[CrossRef] [PubMed]

Schleske, M. M.

G. E. Legge, D. G. Pelli, G. S. Rubin, M. M. Schleske, “Psychophysics of Reading—I. Normal Vision,” Vision Res. 25, 239 (1985).
[CrossRef] [PubMed]

G. E. Legge, G. S. Rubin, D. G. Pelli, M. M. Schleske, “Psychophysics of Reading—II. Low Vision,” Vision Res. 25, 253 (1985).
[CrossRef] [PubMed]

Shlaer, S.

S. Hecht, S. Shlaer, “Intermittent Stimulation by Light. V. The Relation Between Intensity and Critical Frequency for Different Parts of the Spectrum,” J. Gen. Physiol. 19, 965 (1936).
[CrossRef] [PubMed]

Steinman, R. M.

R. M. Steinman, R. J. Cuntiz, “Fixation of Targets Near the Absolute Foveal Threshold,” Vision Res. 8, 277 (1968).
[CrossRef] [PubMed]

Timberlake, G. T.

G. T. Timberlake, E. Peli, E. A. Essock, R. A. Augliere, “Reading with a Macular Scotoma. II. Retinal Locus for Scanning Text,” Invest. Ophthalmol. Vis. Sci. 28, 1268 (1987).
[PubMed]

Young, R. S. L.

R. S. L. Young, J. Price, J. Harrison, “Psychophysical Study of Rod Adaptation in Patients with Congenital Stationary Night Blindness,” Clin. Vision Sci. 1, 137 (1987).

Clin. Vision Sci.

R. S. L. Young, J. Price, J. Harrison, “Psychophysical Study of Rod Adaptation in Patients with Congenital Stationary Night Blindness,” Clin. Vision Sci. 1, 137 (1987).

Invest. Ophthalmol. Vis. Sci.

G. T. Timberlake, E. Peli, E. A. Essock, R. A. Augliere, “Reading with a Macular Scotoma. II. Retinal Locus for Scanning Text,” Invest. Ophthalmol. Vis. Sci. 28, 1268 (1987).
[PubMed]

J. Gen. Physiol.

S. Hecht, S. Shlaer, “Intermittent Stimulation by Light. V. The Relation Between Intensity and Critical Frequency for Different Parts of the Spectrum,” J. Gen. Physiol. 19, 965 (1936).
[CrossRef] [PubMed]

J. Opt. Soc. Am. A

Sci. Am.

D. A. Owens, “The Resting State of the Eyes,” Sci. Am. 72, 378 (1984).

Vision Res.

R. M. Steinman, R. J. Cuntiz, “Fixation of Targets Near the Absolute Foveal Threshold,” Vision Res. 8, 277 (1968).
[CrossRef] [PubMed]

H. R. Blackwell, O. M. Blackwell, “Rod and Cone Receptor Mechanisms in Typical and Atypical Congenital Achromatopsia,” Vision Res. 1, 62 (1961).
[CrossRef]

J. M. Daitch, D. G. Green, “Contrast Sensitivity of the Human Peripheral Retina,” Vision Res. 9, 947 (1969).
[CrossRef] [PubMed]

G. E. Legge, D. G. Pelli, G. S. Rubin, M. M. Schleske, “Psychophysics of Reading—I. Normal Vision,” Vision Res. 25, 239 (1985).
[CrossRef] [PubMed]

G. E. Legge, G. S. Rubin, D. G. Pelli, M. M. Schleske, “Psychophysics of Reading—II. Low Vision,” Vision Res. 25, 253 (1985).
[CrossRef] [PubMed]

Other

Committee on Vision: Working Group on Night Vision. Symposium on Night Vision (National Academy Press, Washington DC, 1987).

F. A. Geldard, Human Senses (Wiley, New York, 1953).

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Figures (6)

Fig. 1
Fig. 1

Video display as seen by the subject. The inset illustrates that, in the viewing conditions of this study, the subject’s fixation is obscured by a central scotoma (as shown here by the obscuration of the letter A in the word BEAR). Also shown are four orientation dots which mark the boundaries of the window.

Fig. 2
Fig. 2

Apparatus used in creating a video text display that only the rods could read. Text is scrolled across a window in a mask (M) that covered the computer monitor (CM) screen. Neutral density (ND) and chromatic (CF) filters were interposed to create suitable scotopic luminance conditions. To provide magnification and help accommodation, the subject viewed the text through a +8 diopter lens(L). Also shown are a tape recorder (TR), printer (P), and computer (CPU).

Fig. 3
Fig. 3

Psychophysical estimates of rod and cone thresholds were obtained on the apparatus. The frequency of seeing curves on the left are for rod thresholds obtained using the full window criterion. Shown on the right are estimates of the cone thresholds from several methods. The frequency-of-seeing curves were obtained using the foveal window criterion. The arrows on the right are estimates obtained using the full window criterion during the cone plateau phase of the dark adaptation curve. The arrow designated CSNB shows the threshold obtained from a night blind patient.

Fig. 4
Fig. 4

Reading rate as a function of scanning rate for different character luminances. The reading rate is the product of scanning rate and percent of reading accuracy. The diagonal line represents perfect reading accuracy at all scan rates. Subjects 2,3,4, and 5 were tested 0.5, 1.0, and 1.5 log units above their rod threshold. For subject 1, the luminances were 1.0,1.5, and 2.0 log units. The maximum reading rate for a given condition is illustrated by the peak of the function.

Fig. 5
Fig. 5

Comparison of the maximum reading rate of the first replication vs the fifth. The data were derived from those shown in Fig. 4 for different subjects and character luminances. The solid line represents the locus of points in which the two replications have identical performance.

Fig. 6
Fig. 6

Maximum reading rates as a function of text luminance as determined in the present study (open symbols). In general, reading rates improve with text luminance over a range in which only the rods could see. The arrows on the left are estimates of rod thresholds made using the full window criterion. The arrows on the right are estimates of cone thresholds made using the same criterion during the cone plateau phase. Results from a previous study9 are also plotted (solid symbols, rectangle for their subject DR and diamond for their subject MK) for comparison.

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