Abstract

The distances at which a series of rectangular test objects are visible were determined experimentally. These test objects were black opaque rectangles having variable length-width ratios and were viewed against a trans-luminated background. Using these data, and an assumed nystagmic motion of the eyeball, the summated temporal illuminance gradients on the retina were computed. These values were found to be essentially constant, even though the length-width ratios of the test objects varied from 1 to 4050. Assuming a motionless eyeball, that is, perfect fixation, the summated values of ΔI were computed for the same observational conditions, ΔI being defined as the difference between the average illuminance incident on adjacent cones in the retinal mosaic. The values of summated ΔI are not constant. Since all of these test objects were just visible at the distance measured, they may be considered as being equal to each other with respect to their ability to excite a threshold neural response. It seems reasonable to conclude, therefore, that since the values of the summated temporal gradients are constant they are the most significant indices of the relative magnitudes of the neural responses. In our opinion these results lend considerable support to the assumption that the perception of inhomogeneities of luminance in the visual field is dependent directly upon the temporal illuminance gradients to which the retinal receptors are subjected by virtue of the movement of the image with respect to the retinal mosaic.

© 1948 Optical Society of America

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References

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  1. L. A. Jones and G. C. Higgins, “Photographic granularity and graininess. III. Some characteristics of the visual system of importance in the evaluation of graininess and granularity,” J. Opt. Soc. Am. 37, 217 (1947).
    [Crossref] [PubMed]
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    [Crossref]
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    [Crossref]
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    [Crossref]
  5. G. A. Fry, “Relation of the configuration of a brightness contrast border to its visibility,” J. Opt. Soc. Am. 37, 166 (1947).
    [Crossref] [PubMed]
  6. E. S. Lamar, S. Hecht, S. Schlaer, and C. D. Hendley, “Size, shape, and contrast in detection of targets by daylight vision. I. Data and analytical description,” J. Opt. Soc. Am. 37, 531 (1947).
    [Crossref] [PubMed]

1947 (3)

1940 (1)

1934 (1)

F. H. Adler and F. Fliegelman, “Influence of fixation on the visual acuity,” Arch. f. Ophthalm. 12, 475 (1934).
[Crossref]

1920 (1)

Adler, F. H.

F. H. Adler and F. Fliegelman, “Influence of fixation on the visual acuity,” Arch. f. Ophthalm. 12, 475 (1934).
[Crossref]

Fliegelman, F.

F. H. Adler and F. Fliegelman, “Influence of fixation on the visual acuity,” Arch. f. Ophthalm. 12, 475 (1934).
[Crossref]

Fry, G. A.

Hartline, H. K.

Hecht, S.

Hendley, C. D.

Higgins, G. C.

Jones, L. A.

Lamar, E. S.

Reeves, P.

Schlaer, S.

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Figures (6)

Fig. 1
Fig. 1

The distribution of illuminance on the retina, at the limit of visibility, for a rectangular test object having a length-width ratio of 100.

Fig. 2
Fig. 2

Curves showing the amplitudes of illuminance to which retinal cones are subjected during one-half cycle of the physiological nystagmus when the rectangular test object having a length-width ratio of 100 is at the threshold of visibility.

Fig. 3
Fig. 3

Curves showing the rate of change of illuminance incident on the retinal cones during one-half cycle of the physiological nystagmus when the rectangular test object having a length-width ratio of 100 is at the threshold of visibility.

Fig. 4
Fig. 4

Diagram showing the distribution of illuminance on the retinal mosaic at the limit of visibility for the square test object.

Fig. 5
Fig. 5

Schematic diagram for the resolution of the random motion of the eye into the component perpendicular to the long dimension of the test object.

Fig. 6
Fig. 6

Diagram showing the distribution of illuminance on the retinal mosaic at the limit of visibility for the rectangular test object having a length-width ratio of 100.

Tables (3)

Tables Icon

Table I Summated average temporal gradients at the limit of visibility of rectangular test objects varying with respect to the length-width ratio.

Tables Icon

Table II Average temporal gradient per cone at the limit of visibility of rectangular test objects varying with respect to the length-width ratio.

Tables Icon

Table III Total summated ΔI at the limit of visibility of rectangular test objects varying with respect to the length-width ratio.

Equations (1)

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G Av = 1.9 Z + 0.64 N Z .