Abstract

A model of threshold and suprathreshold vision in relation to variation of object size is proposed. An important factor in suprathreshold vision is the signal-contrast loss in optical and neural components; in threshold vision, an important additional factor is the manner in which the brain acts on retinal noise. The signal-contrast loss has been measured in terms of a suprathreshold signal-transfer function for circular signals. In threshold vision, the noise processes are shown to predominate and the signal-contrast losses to be insignificant. Therefore signal-transfer functions cannot be deduced solely from threshold measurements; indeed, peak performance in suprathreshold vision is reached at object size one-tenth that at threshold. In suprathreshold vision, performance is shown to depend on a balance between optical unsharpness and neural sharpening (lateral inhibition). Contrast loss due to neural unsharpness (summation) appears to be insignificant in foveal vision and only partially significant in peripheral vision. Hence neural properties such as transfer functions, receptive-field sizes, and the spatial extent of neural interactions cannot be deduced from over-all measurements on the eye without correction for optical unsharpness.

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  1. The term threshold vision here relates to simultaneous contrast or incremental (including decremental) threshold, although the concepts discussed may well apply also to absolute thresholds.
  2. G. A. Hay, Nature 211, 1380 (1966).
  3. Signal contrast at any stage in the visual process is here defined in the form C = | I1 - Io |/ Io, where Io and I1 are the mean luminances, brightnesses, pulse rates, etc., associated with the background and a specified part of the object detail, respectively.
  4. F. Ratliff, Mach Bands (Holden-Day, San Francisco, 1965).
  5. The present analysis refers to the steady-state sensation of natural vision in which the effects of temporal phenomena such as saccades are averaged.
  6. O. Dupuy, Vision Res. 8, 1507 (1968).
  7. R. H. Morgan, Am. J. Roentgenol. 93, 982 (1965).
  8. Hl. de Vries, Physica 10, 553 (1943).
  9. A. Rose, Proc. IRE, 30, 295 (1942).
  10. A. Rose, J. Opt. Soc. Am. 38, 196 (1948).
  11. H. R. Blackwell, J. Opt. Soc. Am. 36, 624 (1946).
  12. J. J. DePalma and E. M. Lowry, J. Opt. Soc. Am. 52, 328 (1962).
  13. E. M. Lowry and J. J. DePalma, J. Opt. Soc. Am. 51, 740 (1961).
  14. A. S. Patel and R. W. Jones, J. Opt. Soc. Am. 58, 696 (1968).
  15. L. L. Sloan, Vision Res. 8, 901 (1968).
  16. J. Mandelbaum and L. L. Sloan, Am. J. Ophthalmol. 30, 581 (1947).
  17. O. Bryngdahl, J. Opt. Soc. Am. 56, 811 (1966).
  18. N. W. Taylor, J. Opt. Soc. Am. 52, 820 (1962).
  19. R. W. Gubisch, J. Opt. Soc. Am. 57, 407 (1967).
  20. J. E. Dowling and B. B. Boycott, Proc. Roy. Soc. (London) B166, 80 (1966).
  21. F. W. Campbell and R. W. Gubisch, J. Physiol. (London) 186, 558 (1966).

Blackwell, H. R.

H. R. Blackwell, J. Opt. Soc. Am. 36, 624 (1946).

Boycott, B. B.

J. E. Dowling and B. B. Boycott, Proc. Roy. Soc. (London) B166, 80 (1966).

Bryngdahl, O.

O. Bryngdahl, J. Opt. Soc. Am. 56, 811 (1966).

Campbell, F. W.

F. W. Campbell and R. W. Gubisch, J. Physiol. (London) 186, 558 (1966).

de Vries, Hl.

Hl. de Vries, Physica 10, 553 (1943).

DePalma, J. J.

E. M. Lowry and J. J. DePalma, J. Opt. Soc. Am. 51, 740 (1961).

J. J. DePalma and E. M. Lowry, J. Opt. Soc. Am. 52, 328 (1962).

Dowling, J. E.

J. E. Dowling and B. B. Boycott, Proc. Roy. Soc. (London) B166, 80 (1966).

Dupuy, O.

O. Dupuy, Vision Res. 8, 1507 (1968).

Gubisch, R. W.

F. W. Campbell and R. W. Gubisch, J. Physiol. (London) 186, 558 (1966).

R. W. Gubisch, J. Opt. Soc. Am. 57, 407 (1967).

Hay, G. A.

G. A. Hay, Nature 211, 1380 (1966).

Jones, R. W.

A. S. Patel and R. W. Jones, J. Opt. Soc. Am. 58, 696 (1968).

Lowry, E. M.

J. J. DePalma and E. M. Lowry, J. Opt. Soc. Am. 52, 328 (1962).

E. M. Lowry and J. J. DePalma, J. Opt. Soc. Am. 51, 740 (1961).

Mandelbaum, J.

J. Mandelbaum and L. L. Sloan, Am. J. Ophthalmol. 30, 581 (1947).

Morgan, R. H.

R. H. Morgan, Am. J. Roentgenol. 93, 982 (1965).

Patel, A. S.

A. S. Patel and R. W. Jones, J. Opt. Soc. Am. 58, 696 (1968).

Ratliff, F.

F. Ratliff, Mach Bands (Holden-Day, San Francisco, 1965).

Rose, A.

A. Rose, J. Opt. Soc. Am. 38, 196 (1948).

A. Rose, Proc. IRE, 30, 295 (1942).

Sloan, L. L.

J. Mandelbaum and L. L. Sloan, Am. J. Ophthalmol. 30, 581 (1947).

L. L. Sloan, Vision Res. 8, 901 (1968).

Taylor, N. W.

N. W. Taylor, J. Opt. Soc. Am. 52, 820 (1962).

Other (21)

The term threshold vision here relates to simultaneous contrast or incremental (including decremental) threshold, although the concepts discussed may well apply also to absolute thresholds.

G. A. Hay, Nature 211, 1380 (1966).

Signal contrast at any stage in the visual process is here defined in the form C = | I1 - Io |/ Io, where Io and I1 are the mean luminances, brightnesses, pulse rates, etc., associated with the background and a specified part of the object detail, respectively.

F. Ratliff, Mach Bands (Holden-Day, San Francisco, 1965).

The present analysis refers to the steady-state sensation of natural vision in which the effects of temporal phenomena such as saccades are averaged.

O. Dupuy, Vision Res. 8, 1507 (1968).

R. H. Morgan, Am. J. Roentgenol. 93, 982 (1965).

Hl. de Vries, Physica 10, 553 (1943).

A. Rose, Proc. IRE, 30, 295 (1942).

A. Rose, J. Opt. Soc. Am. 38, 196 (1948).

H. R. Blackwell, J. Opt. Soc. Am. 36, 624 (1946).

J. J. DePalma and E. M. Lowry, J. Opt. Soc. Am. 52, 328 (1962).

E. M. Lowry and J. J. DePalma, J. Opt. Soc. Am. 51, 740 (1961).

A. S. Patel and R. W. Jones, J. Opt. Soc. Am. 58, 696 (1968).

L. L. Sloan, Vision Res. 8, 901 (1968).

J. Mandelbaum and L. L. Sloan, Am. J. Ophthalmol. 30, 581 (1947).

O. Bryngdahl, J. Opt. Soc. Am. 56, 811 (1966).

N. W. Taylor, J. Opt. Soc. Am. 52, 820 (1962).

R. W. Gubisch, J. Opt. Soc. Am. 57, 407 (1967).

J. E. Dowling and B. B. Boycott, Proc. Roy. Soc. (London) B166, 80 (1966).

F. W. Campbell and R. W. Gubisch, J. Physiol. (London) 186, 558 (1966).

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