Light & Engineering Vol. 24, No. 1, pp. 12-20, 2016 Svetotekhnika No. 2, 2016 THE EFFECTS OF HIGH LUMINANCE OBJECTS ON PERIPHERAL TARGET DETECTION IN MESOPIC CONDITIONS Can Cengiz, Mikko Maksimainen, Marjukka Puolakka, and Liisa Halonen Department of Electrical Engineering and Automation, Aalto University E-mail: can.cengiz@aalto.fi ABSTRACT Advanced visual research is involved in the study of the dependencies of visual response on the distribution of adapting luminance across the visual field. <...> In this work, two different street lighting adaptation conditions were applied by having the subjects to adapt to different background images in a laboratory setting. <...> The difference in the background images is that one includes street luminaires and other light spots, whereas the other does not. <...> Ten subjects (mean age 30 years) participated in the experiment. <...> The subjects were asked to indicate the detection of targets appearing at different eccentricities (from –750 to 750). <...> The results indicate that the high luminance objects affect peripheral target detection in mesopic lighting conditions. <...> Contrast threshold values for the targets close to high luminance objects and in the periphery (200, 300,450 and 600) with non-uniform surroundings were decreased in the background without street luminaires and other light spots. <...> Keywords: mesopic photometry, adaptation, contrast threshold, peripheral vision INTRODUCTION A definition of the visual adaptation field in terms of its extent and shape is needed in order to implement the CIE 191 system of mesopic photometry [1], which is valid luminance in range 0.005 cd/ m2–5 cd/ m2. <...> Visual performance at mesopic light levels is affected by luminance distribution of the background where the eye is adapted. <...> Experimental set-up: the distance between the subject and the fixation point is 96 cm, the distance between the projector and the corresponding central point of the projection is 160 cm, the angle between projectors is 60˚ dicate that local luminance of the target is an essential factor in peripheral target detection in non-uniform backgrounds rather than average luminance of the background [2, 3, 4]. <...> Background images a) with luminaires, b) without LED lamp luminaires of luminance distribution and target eccentricity on visual performance. <...> In driving conditions, the visual field includes both very low luminance (e.g. <...>