Degree of Applicability and Consequences of Inappropriate Use of Units of Light

Abstract

Since light is defined quantitatively as radiant energy evaluated according to the CIE photopic luminosity curve, ordinary t units are inappropriate whenever the organism's spectral sensitivity differs markedly from the CIE curve. Examples of differing spectral sensitivities include those of animals, of color defective individuals, and curves for all individuals under low light levels or with large fields. Calculations are presented of the amount of error involved when units of light are used for these inappropriate conditions; alternative solutions to the problem are discussed.

Are colour vision standards justified for the transport industry?

“…Their results are given in Figure I and are consistent with the more extensive data of Kinnear (1986). Both types of protan observer can be expected to display a reduced sensitivity not only for red lights but also for yellow and white signals (Kinney, 1967;CIE, 1978;Cole and Vingrys, 1983). Not surprisingly, Verriest et al ( 1980) reported field trial data showing that protans have recognition Transport cofour uision stundards: A.…”

“…One further important consideration for the transport industry is the visual range at which coloured signal lights are seen. Protans have a reduced sensitivity to red lights and their limited visual range to red signals is elucidated by the calculations of Kinney (1967) and demonstrated by her field trial (Kinney, Paulson and Beare, 1979a). Furthermore, the studies of Hager (1963) and of Verriest et al (1980) show that protan drivers are at greater risk of having a road accident presumably because of their loss of visual range.…”

“…It is widely accepted that protans have a reduced sensitivity to longer wavelengths (Wright, 1946;Verriest, 1971;CIE, 1978). In relative terms, this loss of luminosity appears to be the same both for protanomalous and for protanopic observers ( Kinney, 1967) although Kinnear (1986) has shown that the degree of loss is a function of the severity of the protan defect. Cole and Vingrys ( 1983) show that both protanomals and protanopes have a similar reduction in visual range to deep red lights but that protanomals are not as disadvantaged with orangish-red colours.…”

Validation of the Holmes‐wright Lanterns for Testing Colour Vision*

“…A related question concerns the performance of protan observers at the lanterns. Protanomals and protanopes have reduced luminosity to red light and will have higher than normal thresholds for red signals and to a lesser extent white signals also (Kinney, 1967;CIE, 1975). They can be expected to have a substantially shorter visual range for coloured signal lights.…”