Samenvatting
CIE Report No.19/2 (1981) has shown that the effects of lighting upon visual performance depend importantly upon three parameters: a)the visibility of task details described by C; b)the demand for speed and accuracy of task performance described by D; and c) age. New analyses of individual differences in visual sensitivity permit descriptions of responses to lighting parameters of entire populations. A new version of the Visual Performance Index of 19/2 is here described suitable for evaluating the effectiveness of different installations of road lighting.