The effect of background luminance on the brightness of flashes

Color properties of the contrast flash effect: Monoptic vs dichoptic comparisons

“…However we also find that a given contrast flash is equally effective in raising test flash threshold whether presented monoptically or dichoptically. In this respect, contrast flashes act quite differently than steady backgrounds, which in our experiment, and so far as we know in all previous ones, have no effect at all dichoptically (Whittle and Challands, 1969). Our contrast flashes also differ from steady backgrounds in having what appears to be a much narrower action spectrum: the difference in effectiveness between a red light and a green one, as measured by the threshold elevation of a red test flash, is much greater when these lights are used as contrast flashes than when they are used as steady backgrounds.…”

“…It appears that steady lightswhether used as backgrounds (Stiles, 1959: Whittle andChallands, 1969;Whittle, 1973) or surrounds (Westheimer, 1966;McKee and Westheimer, 1970), raise threshold and decrease brightness by way of a retinal process, as evidenced by their failure to have any effect dichoptically, and by their action spectra, which agree closely with those of the receptors. On the other hand, flashed backgrounds (Battersby and Wagman, 1962) and surrounds (Fiorentini er al., 1972;Weisstein, 1972) can raise threshold and lower brightness dichoptically.…”

A model for contrast discrimination with incremental and decremental test patches

“…It is known that although over much of its range the response of the visual system is a linear function of the logarithm of luminance (Weber's Law), at low luminances the response function flattens out (Whittle & Challands, 1969). In equation (I), which contains a description of the initial non-linear transformation of luminance by our model operator, the input luminance is simply log transformed: we have assumed up to this point that Weber's Law holds across the whole range of luminance.…”

Lightness, equivalent backgrounds, and anchoring

“…The aim ofthe first process is to define a scale of relative gray values (Arend, 1985;Blake, 1985;Gilchrist, Delman, & Jacobsen, 1983;Horn, 1974;Hurlbert, 1986;Land & McCann, 1971;Whittle & Challands, 1969). The aim of the second process is to "anchor" such a scale to a common reference, so that each surface can be assigned an absolute lightness (Cataliotti & Gilchrist, 1995).…”