Luminance Difference Thresholds Research Articles

Road Marking Contrast Threshold for the Elderly and the Impact of Glare

ABSTRACT As the global population continues to age, with projections indicating that individuals over 60 will comprise 17% of the world’s population by 2030, it is crucial to address the disparity between current road lighting guidelines, based on data from healthy young adults, and the needs of elderly drivers. This study examines the impact of age and glare on contrast thresholds for individuals above 60 years old in the context of road lighting and its effect on detecting road marking arrows. Results indicate a large negative effect of age and glare, such that the required luminance difference between the road marking arrow and the background should be increased up to a factor of 2 for elderly compared to young drivers. We also found that measured luminance difference thresholds increased for elderly participants compared to the younger ones. In addition, the results show a poor agreement with Adrian’s visibility model which can only be slightly improved by using a different measure for the veiling luminance. Still, given these findings, the current European standard EN13201 should adapt the calculation of the threshold increment to also accommodate the needs for the elderly drivers and warranting safe roadways for the aging population.

Do pupillary responses during authentic slot machine use reflect arousal or screen luminance fluctuations? A proof-of-concept study.

Modern slot machines are among the more harmful forms of gambling. Psychophysiological measures may provide a window into mental processes that underpin these harms. Here we investigated pupil dilation derived from eye tracking as a means of capturing changes in sympathetic nervous system arousal following outcomes on a real slot machine. We hypothesized that positively reinforcing slot machine outcomes would be associated with increases in arousal, reflected in larger pupil diameter. We further examined the contribution of game luminance fluctuations on pupil diameter. In Experiment 1A, experienced slot machine gamblers (N = 53) played a commercially-available slot machine in a laboratory for 20 minutes while wearing mobile eye tracking glasses. Analyses differentiated loss outcomes, wins, losses-disguised-as-wins, and (free-spin) bonus features. Bonus features were associated with rapid increases in pupil diameter following the onset of outcome-related audiovisual feedback, relative to losses. In Experiment 1B, luminance data were extracted from captured screen videos (derived from Experiment 1A) to characterize on-screen luminance changes that could modulate pupil diameter. Bonus features and wins were associated with pronounced and complex fluctuations in screen luminance (≈50 L and ≈25L, respectively). However, the pupil dilation that was observed to bonus features in Experiment 1A coincided temporally with only negligible changes in screen luminance, providing partial evidence that the pupil dilation to bonus features may be due to arousal. In Experiment 2, 12 participants viewed pairs of stimuli (scrambled slot machine images) at luminance difference thresholds of ≈25L, ≈50L, and ≈100L. Scrambled images presented at luminance differences of ≈25L and greater were sufficient to cause pupillary responses. Overall, pupillometry may detect event-related changes in sympathetic nervous system arousal following gambling outcomes, but researchers must pay careful attention to substantial in-game luminance changes that may confound arousal-based interpretations.

Restitution of visual functions in cerebrally blind children

In adult patients who suffer from a visual field defect due to cerebral lesions, visual functions can be restored by systematic visual field training. Such visual field training is not feasible in young, brain-damaged children, who are unable to cooperate like adults. We have already shown earlier [Werth, R., & Moehrenschlager, M. (1999). The development of visual functions in cerebrally blind children during a systematic visual field training. Restorative Neurology and Neuroscience, 15, 229–241.] that systematic visual field training, which requires no ability to understand instructions or to cooperate, is successful in brain-damaged children and may lead to complete recovery of the visual field within 3 months. The present study provides more behavioral evidence and a control of intraocular light scatter. In addition to the earlier study, the luminance difference thresholds in the recovered visual field were compared with those of a normal control group. Seventeen children aged 1–4 years who had been blind for more than 1 year after perinatal asphyxia and two children suffering from homonymous hemianopia due to asphyxic-ischemic lesions participated in systematic visual field training. The functional visual field was assessed with a specially designed arc perimeter. Visual functions developed within a training period of 3 months in 11 children who received visual field training, whereas there was no recovery in the control group ( N = 37). The findings support the assumption that systematic visual field training facilitates the development of vision in cerebrally blind children. In two children who recovered from blindness, it was shown in functional magnetic resonance imaging (fMRI) that brain tissue in the area of the visual cortex contralateral to the blind visual hemifield was activated by light. In two children suffering from asphyxic-ischemic lesions who did not recover only brain tissue in the area of the visual cortex contralateral to the good visual hemifield could be activated by light. These results support the assumption that activity in spared tissue of the striate and extrastriate visual cortex are a necessary condition for recovery of the visual field in children suffering from cerebral blindness.

On change of luminance difference threshold in periodic fluctuation of visual field luminance

On change of luminance difference threshold in periodic fluctuation of visual field luminance

高齢者の文字の読みやすさと所要照度に関するVisibility Levelの観点からの検討

The recommended illuminance in the Japanese lighting standard (JIS Z 9110) was determined based on Indow and Kawai's experimental study concerning the relationship between illuminance and readability of printed text. As the observers in the experiment were young, the recommended illuminance derived from the experiment cannot be applied directly to older people. To estimate the recommended illuminance for older people, a set of numerical analyses wasconducted. We found that the readability scale in the above experimental study correlates with the Visibility Level (VL) defined by CIE publication No.19/21. The luminance difference threshold (ΔLmin) derived from the contrast threshold function (Cth) of the CIE publication was divided into two parts (ΔLaf for foveal adaptation and ΔLeq for veiling luminance), assuming ΔLmin=ΔLaf+ΔLeq. After considering age factors in each part, the luminance difference threshold function ΔLmin*was reconstructed. Applying the ΔLmin* function to the VL analysis, the recommended illuminance for older people was estimated. The result shows that at least about 700 lx of illuminance may be recommended for older people reading 3-mm high printed characters. The visibility level analysis is a useful method for assessing readability considering age-related effects.

海上における物標の視認と見張り

The visual perception of the targets at sea is the most important factor for safety and for a good lookout in preventing marine disasters. The International Regulation for Preventing Collision at Sea, 1972 gives rules for a proper look-out (rule 5). What is a proper look-out? This study shows the conditions for the visual perception of the targets at sea in connection with the luminance difference threshold which is referred to the luminance of the sky (about 2 degrees over horizon). Author shows the visual conditions and factors thereof ; they are as follows ; 1. There is a physiological factor which masters and navigation officers on duty can't perceive by sight. 2. The condition for visual perception of the targets is more difference between the luminance of the sky and that of the target than the luminance difference threshold. 3. There are two psychological factors for a good lookout by sight. (1) Masters and navigation officers on duty should remember that there should be existing some targets in case of no sights of them. (2) They should have previous informations of the targets by using ARPA (Automatic Radar Plotting Aids) or RADAR (RAdio Detection And Ranging). 4. There are three physiological factors relating to the luminance difference threshold for a good lookout by sight. (1) They should maintain a proper look-out as long as possible. (2) In daytime, they had better use their sunglasses also in case of not feeling glaring, because of perceiving targets easily by sight. (3) They should use actually the binocular and compass for getting more informations with relative changing direction of targets.

中心窩順応輝度と光幕輝度とに対する輝度差弁別閾の加法性

An objective method for deriving the luminance difference threshold of the eyes adapted to the actual non-uniform field of view was developed by Narisada et. al. This method is based on the theory that an additivity law between the luminance difference threshold determined by the foveal adaptation luminance and that determined by the equivalent veiling luminance exists, but that theory had not been verified experimentally. Therefore, in the present study, the luminance difference theresholds of eyes adapted to fields consisting of various combinations of foveal adaptation luminances and veiling luminances were obtained by observations. These thresholds were compared with those caluculated for the same conditions of adaptation by using the method of Narisada et. al. Because the luminance difference theresholds obtained by observation agree well with those obtained by calculation, it is concluded that the theory has been verified experimentally.

Perception in complex fields under road lighting conditions

Perception in a complex field under road lighting conditions is examined. On the basis of experimental results, and taking into account a lower field factor than that for headlighting, a method to derive the luminance difference threshold is desired. The method allows the influences of the background luminance, the equivalent veiling luminance and the foveal adaptation luminance to be treated separately. By means of the method quality parameters for road lighting can be integrated in relation to perception. (A)

水平線の視認と見張り

The visual perception of the targets at sea is the most important factor for safety and for a good lookout in preventing maritime traffic accidents. This study shows the conditions for being able to perceive the visible horizon between the sky and sea surface and this. Author shows the visual and nautical conditions thereof ; they are as follows; 1. The conditions of visual perception of the line of division between the sky and sea surface is that the luminance difference of the sky (about 2 degrees over horizon) and sea surface (about 2 degrees under horizon) is more than the luminance difference threshold. 2. When nobody can perceive the above line of division (horizon), the visual and nautical environment is indicated as follows; (1) The luminance of the sky (about 2 degrees over horizon) is 0.3cd/m^2. (2) The luminance of the sea surface (about 2 degrees under horizon) is 0.03cd/m^2. (3) The difference luminance threshold is 0.27cd/m^2. But in the case of 0 degree which is a relative direction towards the direction of the sun. 3. A sun altitude with above the mentioned condition is -6〜-9 degrees (1/3〜1/2 duration of astronomical twilight), which is connected with the relative direction towards the direction of the sun. 4. The luminance of the sky and sea surface and the illuminance of the sky have gone up and down with the sun's altitude, and they change rapidly and widely with the case of the time period from sunset and sunrise to -9 degrees of the sun's altitude. 5. When under way the time period from sunset and sunrise to -9 degrees of the sun's altitude is needed to keep a special caution for a good lookout and the safety of the ship.

順応過渡過程における目の感度 : 実効輝度を用いた視認能力の動的評価法(その1)

The dynamic evaluation method of visibility can be simplified by introducing the effective luminance concept. The method is based on the two kind of study that are on the visual sensitivity at transient adaptation and on the effective luminance ratio of visual target. To clarify the sensitivity at transient adaptation to make use of the lighting planning, experimants using uniform field were conducted and found followings : (1) The recovery time of sensitivity is determined only by the ratio between pre-adaptation luminance and field luminance, and the relation between the recovery time and the luminance ratio on a full-logarithmic scale is presented by a linear equation. (2) The luminance difference threshold at early stage of adaptation is determined by pre-adaptation luminance, and any changes of field luminance that are under than the adaptation luminance at the stage have no effect on the transient stage of adaptation.

Lightness and reflectance of munsell gray samples

AbstractA procedure has been designed, on the basis of the general‐type luminance difference threshold data, to find the maximum possible number of the distinguishable luminance levels (the MAX‐NUM‐OF‐LEVELS) between two given luminances with respect to observers under a certain adaptation state. Taking the MAX‐NUM‐OF‐LEVELS as a measure of visibility and applying the procedure to a study of lightness and reflectance of gray samples, it is found that the existing Munsell gray samples with Munsell values 1 to 9, which intend to appear equally spaced, can hardly be regarded as equally‐spaced in lightness, and a group of rearranged reflectances for these gray samples may improve the situation. © 1993 John Wiley & Sons, Inc.

General-type luminance difference threshold data and their uses

General-type luminance difference threshold data are derived from visual performance studies adopting a general approach, taking into consideration viewing conditions; the adaptation luminance being equal to or being unequal to the immediate background luminance. On the basis of these general-type data, a procedure can be designed to find the maximum possible number of the distinguishable luminance levels between two given luminances for observers under a certain adaptation state. By taking the maximum number of levels as a measure of visibility, some predictions of interest have been made, such as better-arranged reflectances for the Munsell grey samples and the various ways in which illuminance contributes to visual communication.

輝度差弁別閾値曲線に関する検討

輝度差弁別閾値曲線に関する検討

Visual Perception in Non-uniform Fields

Adaptation for uniform fields and for non-uniform fields is compared. Experimentally, the luminance difference thresholds for the Foveal Adaptation Luminance (Lf), the Background Luminance (Lb) and the Equivalent Veiling Luminance (Leq) are separately investigated. On the basis of the results, a method to derive the necessary luminance of an object or of the background against which the object in the non-uniform field is seen is explained.

Visibility of targets: Model for calculation

The introduction of the visibility level as a criterion for the obtainable visual information necessitates a metric to allow its quantification. On the basis of Adrian's, Aulhorn's and Blackwell's data a method has been developed to compute the luminance difference thresholds ΔL of visual targets of variable size and positive and negative contrast. Another parameter relevant to ΔL is the observation time to cope with practical viewing conditions in which fixation was found to be restricted to 0.1 to 0.2 s. The effect of age on the threshold contrast and that of disability glare has been incorporated. The numerical description allows the determination of the visibility level VL of objects in the visual field. A practical example of how to obtain VL is presented.

顔の認識と照明レベル

顔の認識と照明レベル

Normative data for pigeon vision

Normative data are reported for the visual acuity, luminance-difference threshold and size-difference threshold of pigeons ( Columba livia). The mean visual acuity was 12.66 c/deg or 2.53 min ( N = 54), the mean log luminance-difference threshold was 0.11 ( N = 105) and the mean size-difference threshold was 0.94 mm ( N = 20).

視感輝度の定量化に関する仮説の検討

視感輝度の定量化に関する仮説の検討

中心窩順応輝度による輝度差弁別いき成分と等価光幕輝度による輝度差弁別いき成分との加法性の検討

中心窩順応輝度による輝度差弁別いき成分と等価光幕輝度による輝度差弁別いき成分との加法性の検討

The role of colours in the formation of subjective contours.

A computer-driven colour television monitor with separate red, green and blue input channels is employed to measure the luminance-difference thresholds for the occurrence of subjective contours, when induction fields and background are of unequal colour. These thresholds are strongly dependent upon the size of the colour difference between the two fields. With increasing difference in colour between induction fields and background, the luminance-difference thresholds necessary to just obtain the subjective contour-effect increase. Various explanations are discussed. Chromatic aberration is not likely to be the main cause for this colour effect, although it has some detrimental influence. At the level of colour-coding mechanisms, lateral interactions between cones or Pi-mechanisms of the same type and interactions between opponent colour codes of the same type are considered. Finally, attention is given to possible psychological factors.