Luminance Conditions Research Articles

The effect of central and peripheral luminance on visual acuity.

Lighting conditions significantly influence visual acuity (VA), visual function, and quality of life. Previous research highlighted a correlation between luminance and VA but left a gap in understanding the impact of surrounding luminance. This study focused on investigating the effects of both central and peripheral luminance on VA. This study aimed to investigate the influence of both central and surrounding luminance on VA through distance VA measurements. A dual-component lighting system was utilized, comprising a self-illuminated ETDRS chart and a skyLED system for consistent surrounding illumination. Two experimental setups were conducted: the first varied the central luminance (25 ± 2-341 ± 10 cd/m²), while the second maintained a constant central luminance (150 ± 5 cd/m²) and varied the surrounding luminance (4 ± 2 cd/m² OFF-105 ± 10 cd/m² ON). Sixty-six participants with refractive errors between 0.0 D and -2.75 D were tested under various lighting conditions. Both uncorrected refractive error (URE) and corrected refractive error (CRE) eyes were evaluated. Paired t-tests were used to evaluate the statistical significance of differences in VA scores. Experiment 1 demonstrated a significant increase in VA scores, with mean improvements of -0.120 LogMAR for URE eyes and -0.073 LogMAR for CRE eyes as chart luminance increased from 26 cd/m² to 153 cd/m². Experiment 2 further showed a notable improvement in VA scores under varied surrounding luminance conditions, with mean improvements of - 0.118 LogMAR for URE eyes and -0.073 LogMAR for CRE eyes as luminance increased from 4 cd/m² to 102 cd/m². This study emphasizes the significant impact of both central and peripheral luminance on VA. The introduction of the skyLED lighting system underlines the importance of optimal lighting for visual performance.

Combined manifestation of two geometric visual illusions.

The present study continued to investigate whether the effects of length misperception caused by cross-shaped (formed by two pairs of the oppositely oriented Müller-Lyer wings) contextual distractors can be explained by the combined manifestation of two different (i.e., the Müller-Lyer and filled-space) geometric illusions of extent. In psychophysical experiments, the luminance of one pair of wings was randomly changed, while the luminance of the other pair remained constant. Two different distractor orientations were used-when the wings with constant luminance formed the right side of the cross or the left side, otherwise. To separately evaluate the manifestation of the Müller-Lyer illusion under different luminance conditions, two distracting crosses of the same orientation were attached to the lateral stimulus terminators in the first series of experiments. In the following four series, a single distracting cross (with different orientation) was attached to one of the lateral stimulus terminators and various combinations of the constant and background luminance were used. To interpret the experimental data, we used the basic computational principles of previously developed quantitative models of hypothetical visual mechanisms underlying the emergence of the Müller-Lyer illusion and the filled-space illusion. It was shown that the results of theoretical calculations adequately approximate the experimental curves obtained for all modifications of stimuli, which strongly supports the suggestion that the joint manifestations of these two illusions can be considered among the main factors determining the features of the illusion investigated.

Peripheral Crowding Magnitude is Similar Under Photopic and Scotopic Luminance Conditions

Peripheral Crowding Magnitude is Similar Under Photopic and Scotopic Luminance Conditions

Comprehensive Assessment of Context-Adaptive Street Lighting: Technical Aspects, Economic Insights, and Measurements from Large-Scale, Long-Term Implementations.

This paper addresses the growing importance of efficient street lighting management, driven by rising electricity costs and the need for municipalities to implement cost-effective solutions. Central to this study is the UNI 11248 Italian regulation, which extends the European EN 13201-1 standard introduced in 2016. These standards provide guidelines for designing, installing, operating, and maintaining lighting systems in pedestrian and vehicular traffic areas. Specifically, the UNI 11248 standard introduces the possibility to dynamically adjust light intensity through two alternative operating modes: (a) Traffic Adaptive Installation (TAI), which dims the light based solely on real-time traffic flow measurements; and (b) Full Adaptive Installation (FAI), which, in addition to traffic measurements, also requires evaluating road surface luminance and meteorological conditions. In this paper, we first present the general architecture and operation of an FAI-enabled lighting infrastructure, which relies on environmental sensors and a heterogeneous wireless communication network to connect intelligent, remotely controlled streetlights. Subsequently, we examine large-scale, in-field FAI infrastructures deployed in Vietnam and Italy as case studies, providing substantial measurement data. The paper offers insights into the measured energy consumption of these infrastructures, comparing them to that of conventional light-control strategies used in traditional installations. The measurements demonstrate the superiority of FAI as the most efficient solution.

Color-appearance-matched data in high-dynamic-range luminance conditions

We report color-appearance-matched data under high-dynamic-range luminance conditions. The experimental method and apparatus proposed in a previous study [J. Opt. Soc. Am. A 36, 1940 (2019)JOAOD60740-323210.1364/JOSAA.36.001940] were used to measure perceptual color shifts in the R, G, B, Y, RB, BG, GY, and YR groups of 16 samples under four dual-illumination conditions at luminance levels of (300 and 4500cd/m2), (20 and 300cd/m2), (80 and 4500cd/m2), and (20 and 4,500cd/m2). We observed a decrease in lightness for all samples, and hue shifts toward blue in R, red in reddish YR, and green in BG samples when the luminance changed from low to high. Correlated changes in lightness and chroma, that is, an increase in lightness change and a decrease in chroma change under the highest luminance contrast (20 and 4500cd/m2), were observed for the Y, GY, and YR samples.

Crowding under scotopic and photopic vision in albino and normal-sighted participants.

Crowding is a phenomenon in which the ability to recognize an object in a clutter deteriorates. It is, therefore, a fundamental aspect of object recognition and crucial in deciphering resolution. For visually impaired individuals, deficiency in crowding has a tremendous effect on vision and may reflect and predict the amount of deterioration in vision. It is well established that albinos suffer much more from crowding than normally sighted individuals under daylight luminance conditions. However, to our knowledge, this study is the first to investigate crowding in albino participants under low light conditions. In this study, we explored the crowding effect in a group of albino participants (n = 9) and a control group of normally sighted participants (n = 9). Crowding was conducted under daylight (photopic vision) and low light (scotopic vision). We measured the visual acuity threshold under crowding in three-letter spacing (0.5, 1, and 1.5) and compared it to a single target. Results indicate that albino participants experienced stronger crowding than the control under the photopic condition, while crowding under the scotopic condition was apparent in the albino but abolished for the control group. These findings highlight the importance of considering luminance when discussing the visually impaired population in general. In particular, it suggests that crowding in albinism is based on a peripheral-like mechanism and may indicate a cessation in visual development.

Scotopic and Photopic Conventional Visual Acuity and Hyperacuity - Binocular Summation.

The purpose of this study was to determine and compare binocular summation (BiS) of conventional visual acuity (cVA) versus hyperacuity (hVA) for photopic and scotopic luminance conditions as a potential biomarker to assess the outcome of interventions on binocular function. Sixteen young adults (age range [years] = 21-31; 8 women; cVA logMAR < 0.0) participated in this study. The Freiburg Visual Acuity Test (FrACT) was used for VA testing and retested on another day. Both cVA and hVA were determined for dark grey optotypes on light grey background. Participants underwent 40minutes of dark adaptation prior to scotopic VA testing. Binocular and monocular VA testing was performed. The eye with better VA over the 2 days of testing was selected, the BiS was quantified (binocular VA - better monocular VA) and repeated measures ANOVAs were performed. Binocular VA exceeded monocular VA for all luminance conditions, VA-types, and sessions. We report BiS estimates for photopic and scotopic cVA and hVA, (logMAR BiS ± SEM [decimal BiS]): photopic = -0.01 ± 0.01 [1.03] and -0.06 ± 0.03 [1.15]; and scotopic = -0.05 ± 0.01 [1.12] and -0.11 ± 0.04 [1.28], respectively). Improvement for binocular vision estimates ranged from 0.01 to 0.11 logMAR. A repeated-measures ANOVA (RM ANOVA) did not reveal significant effects of LUMINANCE or VA TYPE on BiS, albeit a trend for strongest BiS for scotopic hVA (15% vs. 28%, photopic versus scotopic, respectively) and weakest for photopic cVA (3% vs. 12%, photopic versus scotopic conditions, respectively). Our results indicate that BiS of VA is relevant to scotopic and photopic hVA and cVA. It appears therefore a plausible candidate biomarker to assess the outcome of retinal therapies restoring rod or cone function on binocular vision. Binocular summation of visual acuity might serve as a clinical biomarker to monitor therapy outcome on binocular rod and cone-mediated vision.

Effects of Miosis on the Visual Acuity Space under Varying Conditions of Contrast and Ambient Luminance in Presbyopia.

Background: Presbyopia is an age-related ocular condition, typically affecting individuals aged over 40 years, characterized by a gradual and irreversible decline in the eye's ability to focus on nearby objects. Correction methods for presbyopia encompass the use of corrective lenses, surgical interventions (corneal or lens based), and, more recently, the FDA-approved topical administration of 1.25% pilocarpine. While prior research has demonstrated the efficacy of daily pilocarpine eye drop application in enhancing near visual acuity by increasing the depth of focus leveraging the pinhole effect, limited knowledge exists regarding its influence on visual acuity under varying conditions of contrast and ambient luminance. Methods: This study aims to investigate the impact of these variables on visual acuity, employing the VA-CAL test, among 11 emmetropic and 11 presbyopic volunteers who reported subjective difficulties with near vision. This study includes evaluations under natural conditions with a pinhole occluder (diameter of 2 mm), and subsequent administration of 1% pilocarpine (Pilomann, Bausch + Lomb, Laval, Canada). Results: The VA-CAL results demonstrate the expected, statistically significant effects of contrast and ambient luminance on visual acuity in both emmetropic and presbyopic volunteers. Furthermore, in emmetropic individuals, the application of pilocarpine resulted in a statistically significant reduction in visual acuity. In contrast, presbyopes did not exhibit statistically significant differences in the visual acuity space under either the pinhole or pilocarpine conditions when compared to natural conditions. Conclusions: The pharmacological treatment of presbyopia with pilocarpine eye drops, intended to enhance near vision, does not adversely affect visual acuity in presbyopes. This suggests that pilocarpine may offer a viable alternative for individuals averse to wearing corrective eyewear.

Contrast threshold recovery after bleaching during cone‐mediated mesopic adaptation: The effect of test conditions

Aims/Purpose: To determine the optimal luminance conditions and the staircase procedures for evaluating the time course of macular contrast sensitivity recovery after photobleaching in order to decide the best protocol to assess cone‐mediated mesopic adaptation.Methods: The dynamics of contrast threshold (CT) recovery following photopigment bleach were measured psychophysically for five minutes in twenty‐four healthy adults (23.7 ± 3.7 years old). The stimuli used were sine‐wave gratings of low‐spatial frequency (1 cycle‐per‐degree). In each subject, six tests were performed, combining three luminance levels (0.1, 1.0, and 10 cd/m2) and two modified staircase procedures (3‐down/1‐up and 2‐down/1‐up) to estimate CTs. The test order was randomized, conducted in two visits, with a 15‐min washout period between tests. Outlier detection techniques were applied to verify the integrity of the sample. Non‐linear exponential‐based optimization was adopted to fit CT recovery functions to estimate the time constant (τ, seconds) of cone sensitivity recovery and the final CT (CTf, log units). Classical and heteroscedastic ANOVA analyses were performed to assess the effect of test conditions.Results: The 2‐down/1‐up staircase allowed for denser point sampling of CTs measurements than the 3‐down/1‐up. Under the lowest luminance test condition, the CT recovery was modelled by bumpier functions, for both staircases procedures, than the other luminance levels. Mean cone τ increased (21.7, 42.5, and 72.0 seconds (p &lt; 0.001)) and CTf worsened (−1.99, −1.85, and − 1.47 log units (p &lt; 0.001)) as luminance level decreased. The best fit (median R2 = 0.87) was achieved under 1 cd/m2 mesopic luminance conditions. There were no statistically significant differences in mean cone τ and CTf between the two staircases procedures.Conclusions: An intermediate mesopic light level and a 2‐down/1‐up staircase provided the best protocol for assessing cone‐mediated mesopic adaptation.

Poster Session II: SSVEP measurements of color and spatial frequency response in V1.

Recent work from our group (Segala et al, eLife, 2023) shows that the rules for binocular luminance signal combination depend on spatial frequency (SF). Structured patterns show strong interocular suppression while unstructured inputs (mean field disks) do not. Here, we used SSVEPs to ask if SF dependence is also found in chromatic pathways. SSVEPs were recorded from 12 subjects using a canonical V1 template (Poncet & Ales, 2023). Eyes were targeted using shutter goggles and stimuli were contrast-reversing gratings or disks at 5Hz (left eye) and 7Hz (right eye). Experimental factors were stimulus SF (disk, grating 1cpd), chromaticity (LMS, L-M or S-cone isolating) and ocularity (left, right or both). Monocular conditions generated large responses at 2F. In binocular conditions, all 2F responses showed suppression, and significant intermodulation (IM) terms (sums and differences of the inputs - e.g., 2Hz) were present. The magnitude of both suppression and IM in the binocular condition depended on SF and chromaticity; IM amplitudes were higher for gratings compared to disks in the luminance condition, but higher for disks compared to gratings in the chromatic conditions. Overall we found significant differences in the spectral response signatures across all stimulus combinations. All inputs undergo binocular combination in V1 but the rules governing the combination appear to depend on both chromaticity and SF.

Relationship of Low-luminance Visual Acuity with Ocular Aberrations in Older Participants.

This study highlights the importance of twilight adaptation for reliable assessment of low-luminance visual acuity and understanding the relationship between low-luminance visual acuity and ocular aberrations. The human eye experiences reduced visual acuity as luminance decreases owing to reduced retinal and optical resolutions; however, the details are unclear. This study aimed to quantify the effects of refraction, pupil diameter, and ocular aberrations on visual acuity during the transition from high- to low-light environments, thereby contributing to the standardization of low-luminance visual acuity measurements. In total, 27 older participants with a mean age of 70.0 ± 4.1 years were included in this study. Visual acuity was measured according to the Early Treatment Diabetic Retinopathy Study (ETDRS) protocol with three luminance conditions: high luminance (300 cd/m 2 ), low luminance (10 cd/m 2 ), and low luminance with short-term (15-minute) twilight adaptation (10 cd/m 2 ). The mean logarithm of minimum angle of resolution values of visual acuity were -0.09 ± 0.09, 0.10 ± 0.13, and 0.03 ± 0.09 at 300, 10, and 10 cd/m 2 with twilight adaptation, respectively. Multiple regression analysis determined that spherical aberration ( P < .005) and tetrafoil ( P < .005) were significant factors associated with low-luminance visual acuity after twilight adaptation, with an adjusted R2 value of 0.35 for this model ( P < .005). Although the influence of ocular aberrations on low-luminance visual acuity may be relatively modest compared with neural effects, it remains a crucial factor that should not be overlooked. The absence of twilight (or dark) adaptation can cause ocular aberrations and neural effects, potentially leading to inaccuracies in the measurement of low-luminance visual acuity.

Correcting the nighttime lighting data underestimation effect based on light source detection and luminance reconstruction

Nighttime light remote sensing provides a unique perspective on monitoring human activities and socioeconomic conditions. However, early studies on nighttime lighting usually neglected the evaluation of light source detection and luminance conditions in underdeveloped areas. Recent studies have identified a significant nighttime lighting underestimation effect in underdeveloped areas, which makes it difficult to use nighttime lighting as a valid proxy for other variables. To address this problem, this paper proposes a method based on light source detection and luminance reconstruction. Missing luminous pixels will be identified using the rich information provided by daily-scale lighting data and light blooming patterns, and diverse ancillary data will be utilized for the regression reconstruction of luminance values to supplement annual data and to correct the underestimation effect. The effectiveness of this method was verified using data from 7,776 townships in underdeveloped areas in China. The results demonstrated that the proposed method using the corrected NPP/VIIRS data improved light source detection accuracy by 23.23% and 17.71% at the village and township scales, respectively. The correlations between night lighting and proxy variables were also improved. Spearman's rank correlation coefficients between lighting and population, GDP, and electricity consumption at the county scale increased by 0.045, 0.020, and 0.018, respectively. The correlations between lighting and agriculture-related variables also increased to different degrees at both the township and county scales. The proposed method can contribute to improving modeling accuracy and correcting the nighttime lighting underestimation effect in underdeveloped areas. This will provide better support for sustainable development studies.

Effect of low luminance on face recognition in adults with central and peripheral vision loss.

To investigate the effect of low luminance on face recognition, specifically facial identity discrimination (FID) and facial expression recognition (FER), in adults with central vision loss (CVL) and peripheral vision loss (PVL) and to explore the association between clinical vision measures and low luminance FID and FER. Participants included 33 adults with CVL, 17 with PVL and 20 controls. FID and FER were assessed under photopic and low luminance conditions. For the FID task, 12 sets of three faces with neutral expressions were presented and participants asked to indicate the odd-face-out. For FER, 12 single faces were presented and participants asked to name the expression (neutral, happy or angry). Photopic and low luminance visual acuity (VA) and contrast sensitivity (CS) were recorded for all participants and for the PVL group, Humphrey Field Analyzer (HFA) 24-2 mean deviation (MD). FID accuracy in CVL, and to a lesser extent PVL, was reduced under low compared with photopic luminance (mean reduction 20% and 8% respectively; p < 0.001). FER accuracy was reduced only in CVL (mean reduction 25%; p < 0.001). For both CVL and PVL, low luminance and photopic VA and CS were moderately to strongly correlated with low luminance FID (ρ = 0.61-0.77, p < 0.05). For PVL, better eye HFA 24-2 MD was moderately correlated with low luminance FID (ρ = 0.54, p = 0.02). Results were similar for low luminance FER. Together, photopic VA and CS explained 75% of the variance in low luminance FID, and photopic VA explained 61% of the variance in low luminance FER. Low luminance vision measures explained little additional variance. Low luminance significantly reduced face recognition, particularly for adults with CVL. Worse VA and CS were associated with reduced face recognition. Clinically, photopic VA is a good predictor of face recognition under low luminance conditions.

Early Identify and Notify Driver’s Drowsiness by Machine Learning

Abstract: Drowsiness and intoxication are major contributors to car accidents, posing significant risks to road safety. The implementation of effective drowsiness detection technologies could help prevent numerous fatal accidents by alerting fatigued drivers in advance. Various techniques can be adopted to monitor driver attentiveness while driving and provide timely notifications. In the context of self-driving cars, sensors play a crucial role in identifying signs of sleepiness, anger, or extreme emotional changes in drivers. These sensors continuously monitor facial expressions and detect facial landmarks to assess the driver's state and ensure safe driving. Once such changes are detected, the system promptly assumes control of the vehicle, reducing its speed, and alerts the driver through alarms to draw attention to the situation. To enhance accuracy, the proposed system integrates with the vehicle's electronics, tracking its statistics and providing precise results. In this research, we have implemented real-time image segmentation and drowsiness detection using machine learning methodologies. Specifically, an emotion detection method based on Support Vector Machines (SVM) has been employed, utilizing facial expressions. The algorithm underwent testing under varying luminance conditions and exhibited superior performance compared to existing research, achieving an 83.25% accuracy rate in detecting facial expression changes.

Pupil size reflects activation of subcortical ascending arousal system nuclei during rest.

Neuromodulatory nuclei that are part of the ascending arousal system (AAS) play a crucial role in regulating cortical state and optimizing task performance. Pupil diameter, under constant luminance conditions, is increasingly used as an index of activity of these AAS nuclei. Indeed, task-based functional imaging studies in humans have begun to provide evidence of stimulus-driven pupil-AAS coupling. However, whether there is such a tight pupil-AAS coupling during rest is not clear. To address this question, we examined simultaneously acquired resting-state fMRI and pupil-size data from 74 participants, focusing on six AAS nuclei: the locus coeruleus, ventral tegmental area, substantia nigra, dorsal and median raphe nuclei, and cholinergic basal forebrain. Activation in all six AAS nuclei was optimally correlated with pupil size at 0-2 s lags, suggesting that spontaneous pupil changes were almost immediately followed by corresponding BOLD-signal changes in the AAS. These results suggest that spontaneous changes in pupil size that occur during states of rest can be used as a noninvasive general index of activity in AAS nuclei. Importantly, the nature of pupil-AAS coupling during rest appears to be vastly different from the relatively slow canonical hemodynamic response function that has been used to characterize task-related pupil-AAS coupling.

Early Identify and Notify Driver’s Drowsiness by Machine Learning

Abstract: Drunkenness or exhaustion is a leading cause of car accidents, with severe implications for road safety. More fatal accidents could be avoided if fatigued drivers were warned ahead of time. Several drowsiness detection technologies to monitor for signs of inattention while driving and notifying the driver can be adopted. Sensors in self-driving cars must detect if a driver is sleepy, angry, or experiencing extreme changes in their emotions, such as anger. These sensors must constantly monitor the driver’s facial expressions and detect facial landmarks in order to extract the driver’s state of expression presentation and determine whether they are driving safely. As soon as the system detects such changes, it takes control of the vehicle, immediately slows it down, and alerts the driver by sounding an alarm to make them aware of the situation. The proposed system will be integrated with the vehicle’s electronics, tracking the vehicle’s statistics and providing more accurate results. In this paper, we have implemented real-time image segmentation and drowsiness using machine learning methodologies. In the proposed work, an emotion detection method based on Support Vector Machines (SVM) has been implemented using facial expressions. The algorithm was tested under variable luminance conditions and outperformed current research in terms of accuracy. We have achieved 83.25 % to detect the facial expression change.

Field validation of isotropic analytical models for simulating fabric shades

Fabric roller shades are common shading materials used in commercial and residential buildings. Accurately characterizing and modeling shades helps practitioners select the appropriate product and its control strategy based on climate and occupants' priorities, such as visual comfort and view to outdoors. Previous studies established a generalized method for modeling complex fenestration systems using data-driven tabulated bidirectional scattering distribution functions. However, deploying such a method at scale to all fabric shading products on the market is too costly and time-consuming. Analytical models that are based on a limited set of measurements (e.g., normal-normal and normal-hemispherical visible transmittance and reflectance, and directional cut-off angles) can be used to model the wide variety of shading products on the market. This study evaluates the performance of two isotropic analytical models, Roos-Wienold and Modified-Kotey, for modeling fabric roller shades, with a focus on the model's ability to predict occupant visual comfort. The performance evaluation was conducted through laboratory and field measurements and simulations. The results showed that both models are sufficient for predicting vertical illuminance at seated eye-level. Roos-Wienold model was able to predict binary visual comfort classification (glare/no-glare) under a wide range of luminance conditions, while Modified-Kotey model did not perform as well under high-contrast low-adaptation conditions. Both models are insufficient in predicting visual comfort at a four-point scale (e.g., imperceptible, perceptible, disturbing, intolerable). The two isotropic models become less accurate when the fabric exhibits high anisotropy.

Real time vision-based implementation of plant disease identification system on FPGA

Plant diseases have turned into a dilemma as it can cause significant reduction in both quality and quantity of agricultural products. To overcome that loss, we implemented a computer vision based real time system that can identify the type of plant diseases. Computer vision-based applications are computationally intensive and time consuming, so FPGA-based implementation is proposed to have a real time identification of plant diseases. In this paper an image processing algorithm is proposed for identifying two types of disease in Potato leaves. The proposed algorithm works well on images taken under different luminance conditions. The hardware/software-based implementation of the proposed algorithm is done on Xilinx ZYNQ SoC FPGA. Results show that our proposed algorithm achieves an accuracy of up to 90%, whereas the hardware implementation takes 0.095 seconds achieving a performance gain of 76.8 times as compared to the software implementation.

Two distinct types of color spreading induced by different luminance and color conditions in static flank transparency displays.

Flank transparency refers to illusory, phenomenally transparent color spreading induced when narrow colored flanks are added to line segments located within a virtual region. We investigated whether the luminance conditions that induced flank transparency were consistent with predictions based on luminance-contrast-based boundary interactions and the episcotister model for perceptual transparency. Examination of the requirements for the boundary interaction and perceptual transparency revealed that similar luminance conditions are necessary for both; that is, the flank luminance needs to be intermediate between the line and background luminances. We used green and achromatic flanks and systematically varied the luminance of the flanks, line segments, and background. We then asked the observers to rate the subjective certainty of color spreading using a five-point scale. The results showed that the perception of color spreading depended on color as well as luminance conditions. Generally, color spreading was convincing and phenomenally transparent when luminance conditions were consistent with the requirements for boundary interaction and perceptual transparency. In addition, color conditions worked in a facilitatory and inhibitory manner. Moreover, the results revealed that another convincing color spreading could be observed when the flank luminance was lower than the line or background luminance, that is, when the luminance condition for perceptual transparency was not satisfied. The observers' verbal reports indicated that phenomenal transparency was not evident in this color spreading. Overall, the present findings demonstrate that typical transparent color spreading is not the only one observed in the flank transparency display. Different color and luminance conditions can modulate the phenomenal appearance of color spreading, resulting in distinct types of color spreading.

Seeing Auditory Object: Pupillary Light Response Reflects Covert Attention to Auditory Space and Object.

Attention to the relevant object and space is the brain's strategy to effectively process the information of interest in complex environments with limited neural resources. Numerous studies have documented how attention is allocated in the visual domain, whereas the nature of attention in the auditory domain has been much less explored. Here, we show that the pupillary light response can serve as a physiological index of auditory attentional shift and can be used to probe the relationship between space-based and object-based attention as well. Experiments demonstrated that the pupillary response corresponds to the luminance condition where the attended auditory object (e.g., spoken sentence) was located, regardless of whether attention was directed by a spatial (left or right) or nonspatial (e.g., the gender of the talker) cue and regardless of whether the sound was presented via headphones or loudspeakers. These effects on the pupillary light response could not be accounted for as a consequence of small (although observable) biases in gaze position drifting. The overall results imply a unified audiovisual representation of spatial attention. Auditory object-based attention contains the space representation of the attended auditory object, even when the object is oriented without explicit spatial guidance.