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

S Fotios,J Winter,S Völker

doi:10.1177/1477153516672719

S Fotios, J Winter + Show 1 more

Open Access

https://doi.org/10.1177/1477153516672719

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Abstract

An experiment was carried out to investigate how contrast threshold for target detection is affected by the presence of glare and by extraneous light sources using the method of ascending limits. The target was located at either a foveal or a peripheral (10° right) location, glare was adjacent to the foveal location, simulating the headlamps of an oncoming vehicle, and extraneous light sources were at either foveal or peripheral (10° right or left) locations. Contrast threshold for a foveal target without glare was affected mainly by the surrounding local luminance distribution. However, in the presence of glare and also for the peripheral target (both with and without glare) the global luminance distribution matters. Glare increased the contrast needed for detection of the foveal target, but this effect was reduced by the presence of extraneous light sources that were peripheral to the target. For peripheral targets, contrast threshold was also reduced by the presence of extraneous light at a non-target location and this effect was increased in the presence of glare. Glare equations tend to be based on tests using uniform, homogenous fields: these data indicate that, in the presence of extraneous light sources, the influence of glare is overestimated.

Highlights

For the application of mesopic luminances according to the CIE recommended system for mesopic photometry,[1] Joint Technical Committee 1 of the Commission Internationale de l’Eclairage (CIE JTC-1) has requested proposals on how to estimate the adaptation state of a typical observer depending on the task
The influences of glare and extraneous light sources within the visual field were investigated by comparing contrast detection threshold for targets presented at foveal and off-axis locations
The local luminance hypothesis as suggested by others[2,19,36] was again found to be applicable for the foveal target position, i.e. visual performance is influenced mostly by the luminances directly surrounding the target position and it is assumed, that this is applicable to adaptation as well

Summary

Introduction

For the application of mesopic luminances according to the CIE recommended system for mesopic photometry,[1] Joint Technical Committee 1 of the Commission Internationale de l’Eclairage (CIE JTC-1) has requested proposals on how to estimate the adaptation state of a typical observer depending on the task. It is possible to predict the influence of glare with a homogeneous background,[9,10,11] and the influence of luminance on adaptation under a homogeneous background.[12] Moon and Spencer[2] found that under a homogeneous background the size of an extraneous light source has only a small effect and concluded that adaptation is mostly influenced by local luminance surrounding the target position. It is, unknown how all three findings work together under nonhomogeneous circumstances such as those of a real traffic scene with simultaneous inhomogeneities and glare. The wrong location was reported in less than 1% of trials and when this occurred the results were omitted and the trial repeated

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