Mesopic visual efficiency I: detection threshold measurements

Abstract

Achromatic thresholds are measured at three sites to investigate the effects of light spectrum on achromatic detection thresholds in the mesopic region. The results of measurements using quasi-monochromatic targets reveal spectral sensitivity functions with two or three peaks, a so-called 'chromatic effect' which is assumed to be due to the influence of the colour-opponent channels. This chromatic contribution seem to be less significant at lower luminances but it is accentuated for peripheral observation. Results obtained with broadband stimuli show that the contrast threshold, defined in terms of V(), is markedly higher for red targets than for other colours, particularly at lower light levels. For these broadband targets, contrast threshold values calculated using the new spectral sensitivity curves instead of V() are in better agreement with the experimental results, particularly for the peripheral detection task.

Road lighting research for drivers and pedestrians: The basis of luminance and illuminance recommendations

“…54 The mesopic system was derived from two parallel bodies of work, the European MOVE consortium [55][56][57][58] who used and driving on a test track. 62 The mesopic visual response is essentially a weighed combination of the scotopic (S) and photopic (P) responses, and hence the CIE mesopic system 53 provides the weighting factor according to the level of adaptation and the S/P ratio of lighting, this being established by consensus between the two bodies of work.…”

Proposed UK guidance for lighting in residential roads

“…higher rod stimulation) providing improved detection probability and reaction time. 30,[32][33][34][35][36][37][38] In a recent study, a novel apparatus was built with which to measure detection of pavement obstacles under different light sources and illuminances. 9 The results confirmed that obstacle detection increased with increasing illuminance and with higher S/P ratio ( Figure 3).…”

The effects of glare and inhomogeneous visual fields on contrast detection in the context of driving

“…This means that the target luminance was gradually increased until the required task could be carried out, i.e. the target could be detected 3,22 or a specified level of perceived intensity was reached. 21 It is known that the starting point for such an experiment forms an anchor to the response and that if different starting points are used, different results may be obtained.…”

“…This experiment considers variations in target luminance but not size, measuring contrast threshold using the method of ascending limits as used in recent studies. 3,21,22 The independent variables were target position, position of an extraneous light source and glare; the dependent variable was contrast threshold.…”

“…2 In laboratory settings, the luminance of a homogeneous background is used to control the adaptation luminance of the retina. Many of the experiments, which provided the basic research for CIE recommended system, 1 were carried out in laboratories with a homogeneous background, [3][4][5] although some data were gathered in field studies. 6 Foveal eye movements for a car driver after dark tend to fall within a 108 circle centred either on the lane ahead or slightly to the near side, depending on the type of road and hence anticipated hazards.…”