Spatial and temporal limits of vision in the achromat.

Hess, Robert F.; Nordby, Knut

doi:10.1113/jphysiol.1986.sp015981

Cited by 107 publications

(62 citation statements)

References 28 publications

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“…The CSF plotted on a log-log scale has the typical inverted-U shape with a fall-out of sensitivity both at low and at high spatial frequencies (compare with Robson, 1966, at a mean luminance of 20 cd/m 2 , temporal frequency of 1 Hz, and fixed field size). Both observers have normal (extrapolated) visual acuity given the mean luminance level used (Hess & Nordby, 1986, their Figure 6, subject with normal vision).…”

Section: Fitting the Model To Datamentioning

confidence: 99%

The Effect of White-Noise Mask Level on Sinewave Contrast Detection Thresholds and the Critical-Band-Masking Model

Serrano‐Pedraza¹,

Sierra-Vázquez

2006

Span. J. Psychol.

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It is known that visual noise added to sinusoidal gratings changes the typical U-shaped threshold curve which becomes flat in log-log scale for frequencies below 10c/deg when gratings are masked with white noise of high power spectral density level. These results have been explained using the critical-band-masking (CBM) model by supposing a visual filter-bank of constant relative bandwidth. However, some psychophysical and biological data support the idea of variable octave bandwidth. The CBM model has been used here to explain the progressive change of threshold curves with the noise mask level and to estimate the bandwidth of visual filters. Bayesian staircases were used in a 2IFC paradigm to measure contrast thresholds of horizontal sinusoidal gratings (0.25-8 c/deg) within a fixed Gaussian window and masked with one-dimensional, static, broadband white noise with each of five power density levels. Raw data showed that the contrast threshold curve progressively shifts upward and flattens out as the mask noise level increases. Theoretical thresholds from the CBM model were fitted simultaneously to the data at all five noise levels using visual filters with log-Gaussian gain functions. If we assume a fixed-channel detection model, the best fit was obtained when the octave bandwidth of visual filters decreases as a function of peak spatial frequency. Keywords: contrast detection threshold, spatial white noise, critical-band-masking paradigmEl ruido visual añadido a enrejados sinusoidales cambia la típica forma en U de la curva de umbral, que se transforma en una función casi uniforme (en escala log-log) cuando los enrejados son enmascarados por ruido blanco cuya densidad espectral de potencia (o nivel) es alta. Ese hecho se ha explicado mediante el modelo de enmascaramiento basado en bandas críticas (modelo CBM) suponiendo que la anchura de banda relativa (en octavas) de los filtros visuales es constante. Sin embargo, estudios biológicos y psicofísicos apoyan la idea de la variación de la anchura de banda con la frecuencia de sintonía de los filtros. En este trabajo se ha utilizado el modelo CBM para explicar el cambio progresivo de la curva de umbral con el nivel del ruido y, a la vez, para estimar la anchura de banda de los filtros visuales. Para ello, se midieron (utilizando escaleras bayesianas en un paradigma 2IFC) los umbrales de contraste de enrejados sinusoidales (de 0.25 a 8 c/gav), presentados dentro de una ventana Gaussiana fija y enmascarados por ruido blanco 1D estático con cada uno de cinco niveles. Los resultados indican que, en efecto, al aumentar el nivel del ruido, los umbrales de contraste se hacen cada vez mayores y, a la vez, la curva de umbral se va aplanando progresivamente. Utilizando el modelo CBM, los umbrales teóricos se ajustaron a los datos simultáneamente en todos los niveles de ruido suponiendo que la función de ganancia de los filtros visuales es log-Gaussiana y que la detección se lleva a cabo por el filtro sintonizado a la frecuencia del enrejado. Con esos supuestos razonables, ...

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Section: Fitting the Model To Datamentioning

confidence: 99%

The Effect of White-Noise Mask Level on Sinewave Contrast Detection Thresholds and the Critical-Band-Masking Model

Serrano‐Pedraza¹,

Sierra-Vázquez

2006

Span. J. Psychol.

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“…The source of the relationship between sensitivity to sinewave gratings and retinal illuminance seems to require a new theoretical justification. Hess and Nordby (1986b) and Figure 6 in Hess and Nordby (1986a) were digitally scanned at a resolution of 600 dots per inch and the digital versions of these figures were used to extract the coordinates of the data points plotted on them. The empirical data in Figure 1 of Hess and Nordby (1986b) were described by the function CSF(x) = 188 x 0.82 exp [-0.25 …”

Section: Resultsmentioning

confidence: 99%

“…These curves represent fits to data from Figure 1 of Hess and Nordby (1986b) and Figure 6 of Hess and Nordby (1986a), which come from the same normal subject. The empirical CSF was obtained at a reportedly optimal illuminance of 2000 scotopic td (optimal in that sensitivity did not increase significantly at higher illuminance levels) and the empirical acuity limit was obtained by determining the highest frequency that could be resolved at a 100% contrast at each illuminance.…”

Section: Sensitivity As a Function Of Spatial Frequency And Illuminancementioning

confidence: 99%

“…The thick line on the base of the plot indicates the implied relationship between visual acuity (defined as the highest-frequency grating that can be resolved at a 100% contrast) and illuminance. (b) Sensitivity surface constrained to satisfy the empirical acuity versus illuminance (AVI) curve shown as a thick line on the base of the plot (from Figure 1 of Hess & Nordby, 1986b), the empirical ceiling CSF shown as a thick line on the surface at an illuminance of 2000 scotopic td (from Figure 6 of Hess & Nordby, 1986a), and the requirement that, at all frequencies, SVI curves increase with a slope of 0.5 until they reach the ceiling CSF. Note that these three constraints cannot be met simultaneously, as the ceiling CSF can only be reached at frequencies below 1 c/deg.…”

Section: Sensitivity As a Function Of Spatial Frequency And Illuminancementioning

confidence: 99%

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Is the DeVries-Rose to Weber Transition Empirically Possible with Sine-Wave Gratings?

Garcı́a-Pérez

2005

Span. J. Psychol.

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Visual functioning at various retinal illuminance levels is usually measured either by determining grating acuity as a function of light level or by determining how sensitivity to sine-wave gratings changes with retinal illuminance. The former line of research has shown that grating acuity follows a two-branch relationship with retinal illuminance, with the point of discontinuity occurring at the transition from scotopic to photopic vision. Results of the latter line of research have summarily been described as a transition from the DeVries-Rose law to Weber's law, according to which log sensitivity increases linearly with log illuminance with a slope of 0.5 over a range of low illuminances (the DeVries-Rose range) and then levels off and does not increase with further increases of illuminance (the Weber range). This paper aims at determining the compatibility of the results of these two lines of research. We consider empirical constraints from data bearing on the shape of the surface describing contrast sensitivity to sine-wave gratings as a function of spatial frequency and illuminance simultaneously, in order to determine whether they are consistent with a summary description in terms of DeVries-Rose and Weber's laws. Our analysis indicates that, with sine-wave gratings, the DeVries-Rose law can only hold empirically at low spatial frequencies. Keywords: Weber's law, DeVries-Rose law, contrast sensitivity, retinal illuminance, visual acuity Con frecuencia se ha medido la función visual a distintos niveles de iluminancia, bien determinando la agudeza visual para enrejados sinusoidales en función del nivel luminoso o bien determinando la forma en que la sensibilidad a enrejados sinusoidales cambia con la iluminancia. La primera vía de acercamiento ha revelado que la agudeza varía con la iluminancia de acuerdo con una función de dos ramas y un punto de discontinuidad en la transicion de visión escotópica a visión fotópica. Los resultados obtenidos a través de la segunda vía se han resumido aludiendo a una transición de la ley de DeVries-Rose a la de Weber, según la cual el logaritmo de la sensibilidad aumenta linealmente con pendiente 0.5 a medida que aumenta la iluminancia (para niveles bajos de iluminancia que comprenden el llamado rango de DeVries-Rose) pero luego permanece constante e invariante ante sucesivos incrementos de iluminancia (dentro del llamado rango de Weber). Aquí se evalúa la compatibilidad de los resultados obtenidos en estas dos líneas de investigación. Se parte de las restricciones empíricas impuestas por datos que revelan la forma de la superficie de sensibilidad a enrejados sinusoidales en función de la frecuencia espacial y la iluminancia, y se determina si esas restricciones son compatibles con la descripción que ofrecen las leyes de DeVries-Rose y Weber. El análisis muestra que la ley de DeVries-Rose sólo es posible empíricamente para enrejados sinusoidales de baja frecuencia.

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“…TDepartment of Psychology, University of California at San Diego, La Jolla, CA 92093-0109, U.S.A. Nordby, 1986a) and scotopic flicker threshold vs intensity (TVI) profiles measured with frequencies > 8 Hz (Conner, 1982;. At or near 15 Hz, there is a suprathreshold intensity region, adjoining the double-branched flicker TV1 function, within which the perception of flicker completely disappears (see Fig.…”

Section: Introductionmentioning

confidence: 99%

The spectral properties of the two rod pathways

Sharpe¹,

Fach²,

Stockman

1993

Vision Research

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Psychophysical and electroretinographic observations in normal and achromat observers suggest that rod flicker signals have access to at least two retinal pathways: one (q,), slow and sensitive, predominating at scotopic luminance levels, the other (a;), fast and insensitive, predominating at mesopic ones. We have measured steady-state flicker detection sensitivities on background fields ranging from 430 to 640 nm in normal observers. Our results suggest that cone signals can reduce the sensitivity of s;, but have comparatively little effect on A,,. The z; field sensitivities derived from these measurements have been fitted with linear combinations of the scotopic luminosity function, Vi, the M-cone spectral sensitivity function, M,, and the L-cone function, L,. These fits demonstrate a clear cone influence on ni, but they cannot tell us unequivocally whether the influence is from the M-cones, from the L-cones or from both. Accordingly, we made similar measurements in dichromats, who lack one of the two longer wavelength cone types. These measurements revealed an L-cone influence on x; in the deuteranope and an M-cone influence in the protanope. This suggests that both cone types can affect the sensitivity of I$ The finding that in the steady-state cone signals reduce the sensitivity of u; but have Little effect on a,, could suggest that n; signals travel through a faster cone pathway (with its own gain control at which both rod and cone signals can reduce rod threshold), while rc,, signals travel through a separate rod pathway. However, it could simply reflect the fact that nt predominates at higher luminances than 1~~ where the cone excitation level is inevitably greater. To examine the influence of the cones on u. more closely, we: (i) produced transient cone excitation by alternating rodquated 480 and 679 nm fields; and (ii) extended our steady-state measurements to include deep-red backgrounds of 650 and 680 nm. Both experiments revealed a small, but measurable influence of the cones on A~. Rods Temporal sensitivityFlicker Spectral sensitivity Field sensitivity Rodxone interaction INTRODUCTIONPsychophysical data (Conner & MacLeod, 1977;Conner, 1982;Sharpe, Stockman & MacLeod, 1989) and electroretinographic (ERG) recordings (Stockman, Sharpe, Zrenner & Nordby, 1991) in the normal and achromat observer demonstrate that rod flicker signals have access to both a slow and a fast retinal pathway. The slower pathway [labeled a,, after the notation of Stiles (1978)] is more sensitive and dominates from absolute threshold up to low mesopic levels. The faster pathway (labeled nh) is less sensitive and takes over flicker detection only at moderate and high mesopic levels.The two pathways are most clearly revealed in the double-branching of scotopic critical flicker fusion (CFF) vs intensity functions (Hecht, Shlaer, Smith, Haig & Peskin, 1938;Hecht, Shlaer, Smith, Haig & Peskin, 1948;Conner & MacLeod, 1977 et al., 1989). To explain the restricted range of the null, we assume that the intensity dependencies of x0 and ...

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Spatial and temporal limits of vision in the achromat.

Cited by 107 publications

References 28 publications

The Effect of White-Noise Mask Level on Sinewave Contrast Detection Thresholds and the Critical-Band-Masking Model

The Effect of White-Noise Mask Level on Sinewave Contrast Detection Thresholds and the Critical-Band-Masking Model

Is the DeVries-Rose to Weber Transition Empirically Possible with Sine-Wave Gratings?

The spectral properties of the two rod pathways

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