Abstract

Thresholds of visual detectability were determined for signals on a modified 7BP7 cathode-ray tube. Thresholds were determined in units of signal voltage for three pip sizes, all relatively small, and for four screen brightnesses at each of several positions from the line of binocular regard to 20 degrees out from it. The purpose was to determine the limits within which chance eccentricity of view could be a factor in radar detection. The range of impairment from zero to twenty degrees of eccentricity was about 17 db of signal voltage. The course of the impairment is probably not quite linear, with the optimal scope brightness (about 0.16 footlambert for this phosphor), but the slope is a function of scope brightness. For very small pips the data show no region of equal visibility, even within the fovea; direct fixation is required for maximal detection. There being no data based on optically precise stimuli available for comparison with the radar thresholds, an estimate was made of the luminances of the pips and their backgrounds. As estimated, the visual threshold probably varies up to one-log unit or greater over a range of 20 degrees of viewing angle, for the optimal scope background.

© 1949 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. Williams, Bartlett, and King, “Visibility on cathode-ray tube screens: screen brightness,” J. Psych. 25, 455 (1948),
    [Crossref]
  2. L. L. Sloan, “Rate of dark adaptation and regional threshold gradient of the dark-adapted eye: physiologic and clinical studies,” Am. J. Opthal. 30, 705–720 (1947).
  3. W. J. Crozier and A. H. Holway, “Theory and measurement of visual mechanisms. I. A visual discriminometer. II. Threshold stimulus intensity and retinal position,” J. Gen. Physiol. 22, 362 (1939).
    [Crossref]
  4. W. H. Howell, Textbook of Physiology (W. B. Saunders Company, Philadelphia, 1947), see Chapter 23, “Vision,” by T. C. Ruch.
  5. S. R. Wallace, “Intensity discrimination in the peripheral retina,” Psych. Bull. 37, 552 (1940).
  6. K. J. W. Craik and S. J. MacPherson, “The effect of certain operating conditions on the visibility of P.P.I. radar echoes,” Med. Res. Council, UAP, Cambridge, England, No. 16, December3, 1945.
  7. S. B. Williams and N. R. Bartlett, “Visibility on cathode-ray tube screens: problems and methods,” J. Psych. 25, 401–417 (1948).
    [Crossref]
  8. R. M. Hanes and S. B. Williams, “Visibility on cathode-ray tube screens: the effects of light adaptation,” J. Opt. Soc. Am. 38, 363–377 (1948).
    [Crossref] [PubMed]
  9. The writer is indebted to Mrs. Beverly Richards and Mr. Hamilton Mowbray for their services as observers.
  10. W. S. Stiles, “The directional sensitivity of the retina and the spectral sensitivities of the rods and cones,” Proc. Roy. Soc. London,  127B, 64–105 (1939).
    [Crossref]
  11. H. R. Blackwell, “Contrast thresholds of the human eye,” J. Opt. Soc. Am. 36, 624–643 (1946).
    [Crossref] [PubMed]

1948 (3)

Williams, Bartlett, and King, “Visibility on cathode-ray tube screens: screen brightness,” J. Psych. 25, 455 (1948),
[Crossref]

S. B. Williams and N. R. Bartlett, “Visibility on cathode-ray tube screens: problems and methods,” J. Psych. 25, 401–417 (1948).
[Crossref]

R. M. Hanes and S. B. Williams, “Visibility on cathode-ray tube screens: the effects of light adaptation,” J. Opt. Soc. Am. 38, 363–377 (1948).
[Crossref] [PubMed]

1947 (1)

L. L. Sloan, “Rate of dark adaptation and regional threshold gradient of the dark-adapted eye: physiologic and clinical studies,” Am. J. Opthal. 30, 705–720 (1947).

1946 (1)

1940 (1)

S. R. Wallace, “Intensity discrimination in the peripheral retina,” Psych. Bull. 37, 552 (1940).

1939 (2)

W. J. Crozier and A. H. Holway, “Theory and measurement of visual mechanisms. I. A visual discriminometer. II. Threshold stimulus intensity and retinal position,” J. Gen. Physiol. 22, 362 (1939).
[Crossref]

W. S. Stiles, “The directional sensitivity of the retina and the spectral sensitivities of the rods and cones,” Proc. Roy. Soc. London,  127B, 64–105 (1939).
[Crossref]

Bartlett,

Williams, Bartlett, and King, “Visibility on cathode-ray tube screens: screen brightness,” J. Psych. 25, 455 (1948),
[Crossref]

Bartlett, N. R.

S. B. Williams and N. R. Bartlett, “Visibility on cathode-ray tube screens: problems and methods,” J. Psych. 25, 401–417 (1948).
[Crossref]

Blackwell, H. R.

Craik, K. J. W.

K. J. W. Craik and S. J. MacPherson, “The effect of certain operating conditions on the visibility of P.P.I. radar echoes,” Med. Res. Council, UAP, Cambridge, England, No. 16, December3, 1945.

Crozier, W. J.

W. J. Crozier and A. H. Holway, “Theory and measurement of visual mechanisms. I. A visual discriminometer. II. Threshold stimulus intensity and retinal position,” J. Gen. Physiol. 22, 362 (1939).
[Crossref]

Hanes, R. M.

Holway, A. H.

W. J. Crozier and A. H. Holway, “Theory and measurement of visual mechanisms. I. A visual discriminometer. II. Threshold stimulus intensity and retinal position,” J. Gen. Physiol. 22, 362 (1939).
[Crossref]

Howell, W. H.

W. H. Howell, Textbook of Physiology (W. B. Saunders Company, Philadelphia, 1947), see Chapter 23, “Vision,” by T. C. Ruch.

King,

Williams, Bartlett, and King, “Visibility on cathode-ray tube screens: screen brightness,” J. Psych. 25, 455 (1948),
[Crossref]

MacPherson, S. J.

K. J. W. Craik and S. J. MacPherson, “The effect of certain operating conditions on the visibility of P.P.I. radar echoes,” Med. Res. Council, UAP, Cambridge, England, No. 16, December3, 1945.

Ruch, T. C.

W. H. Howell, Textbook of Physiology (W. B. Saunders Company, Philadelphia, 1947), see Chapter 23, “Vision,” by T. C. Ruch.

Sloan, L. L.

L. L. Sloan, “Rate of dark adaptation and regional threshold gradient of the dark-adapted eye: physiologic and clinical studies,” Am. J. Opthal. 30, 705–720 (1947).

Stiles, W. S.

W. S. Stiles, “The directional sensitivity of the retina and the spectral sensitivities of the rods and cones,” Proc. Roy. Soc. London,  127B, 64–105 (1939).
[Crossref]

Wallace, S. R.

S. R. Wallace, “Intensity discrimination in the peripheral retina,” Psych. Bull. 37, 552 (1940).

Williams,

Williams, Bartlett, and King, “Visibility on cathode-ray tube screens: screen brightness,” J. Psych. 25, 455 (1948),
[Crossref]

Williams, S. B.

R. M. Hanes and S. B. Williams, “Visibility on cathode-ray tube screens: the effects of light adaptation,” J. Opt. Soc. Am. 38, 363–377 (1948).
[Crossref] [PubMed]

S. B. Williams and N. R. Bartlett, “Visibility on cathode-ray tube screens: problems and methods,” J. Psych. 25, 401–417 (1948).
[Crossref]

Am. J. Opthal. (1)

L. L. Sloan, “Rate of dark adaptation and regional threshold gradient of the dark-adapted eye: physiologic and clinical studies,” Am. J. Opthal. 30, 705–720 (1947).

J. Gen. Physiol. (1)

W. J. Crozier and A. H. Holway, “Theory and measurement of visual mechanisms. I. A visual discriminometer. II. Threshold stimulus intensity and retinal position,” J. Gen. Physiol. 22, 362 (1939).
[Crossref]

J. Opt. Soc. Am. (2)

J. Psych. (2)

Williams, Bartlett, and King, “Visibility on cathode-ray tube screens: screen brightness,” J. Psych. 25, 455 (1948),
[Crossref]

S. B. Williams and N. R. Bartlett, “Visibility on cathode-ray tube screens: problems and methods,” J. Psych. 25, 401–417 (1948).
[Crossref]

Proc. Roy. Soc. London (1)

W. S. Stiles, “The directional sensitivity of the retina and the spectral sensitivities of the rods and cones,” Proc. Roy. Soc. London,  127B, 64–105 (1939).
[Crossref]

Psych. Bull. (1)

S. R. Wallace, “Intensity discrimination in the peripheral retina,” Psych. Bull. 37, 552 (1940).

Other (3)

K. J. W. Craik and S. J. MacPherson, “The effect of certain operating conditions on the visibility of P.P.I. radar echoes,” Med. Res. Council, UAP, Cambridge, England, No. 16, December3, 1945.

W. H. Howell, Textbook of Physiology (W. B. Saunders Company, Philadelphia, 1947), see Chapter 23, “Vision,” by T. C. Ruch.

The writer is indebted to Mrs. Beverly Richards and Mr. Hamilton Mowbray for their services as observers.

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 (2)

F. 1
F. 1

Relative visibility as a function of distance from fixation point, measured in inches on the scope face. Visibility units are decibels of attenuation of an eight-volt signal required for an appearance threshold. The curve in the lower section is for the optimally biased tube (brightness about 0.16 footlambert). Curves in upper section are at higher biases (lower brightness) and a lower bias. All data are based on the binocular observation, by two subjects, of a small pip 1 µsec. in radial dimension and 1° in azimuth, subtending about 3′ 29″ by 7′ 31″ at the eye.

F. 2
F. 2

Visibility as a function of distance from fixation point for pips of three different sizes. All pips are small by operational standards. Optimal bias used throughout. Visual angles subtended by pips are given in Table II.

Tables (3)

Tables Icon

Table I Brightness of field adjacent to pip, in footlamberts.

Tables Icon

Table II Approximate angles subtended at the eye by pips at half-radius.

Tables Icon

Table III Visibility as a function of viewing angle*

Equations (21)

Equations on this page are rendered with MathJax. Learn more.

1 2 microsec .
1 8
1 4
3 8
5 8
7 8
1 1 8
1 3 8
1 5 8
1 7 8
2 1 8
2 3 8
2 5 8
2 7 8
3 1 8
3 3 8
3 5 8
3 7 8
4 1 8
4 3 8
4 5 8