Brightness Perception Research Articles

Contour Erasure and Filling-in: Old Simulations Account for Most New Observations.

Three recent studies used similar stimulus sequences to investigate mechanisms for brightness perception. Anstis and Greenlee (2014) demonstrated that adaptation to a flickering black and white outline erased the visibility of a subsequent target shape defined by a luminance increment or decrement. Robinson and de Sa (2012, 2013) used a flickering disk or annulus to show a similar effect. Here, a neural network model of visual perception (Francis & Kim, 2012), that previously explained properties of scene fading, is shown to also explain most of the erasure effects reported by Anstis and Greenlee and by Robinson and de Sa. The model proposes that in normal viewing conditions a brightness filling-in process is constrained by oriented boundaries, which thereby define separate regions of a visual scene. Contour adaptation can weaken the boundaries and thereby allow brightness signals to merge together, which renders target stimuli indistinguishable from the background. New simulations with the stimuli used by Anstis and Greenlee and Robinson and de Sa produce model output very similar to the perceptual experience of human observers. Finally, the model predicts that adaptation to illusory contours will not produce contour erasure.

The Oriented Difference of Gaussians (ODOG) model of brightness perception: Overview and executable Mathematica notebooks.

The Oriented Difference of Gaussians (ODOG) model of brightness (perceived intensity) by Blakeslee and McCourt (Vision Research 39:4361-4377, 1999), which is based on linear spatial filtering by oriented receptive fields followed by contrast normalization, has proven highly successful in parsimoniously predicting the perceived intensity (brightness) of regions in complex visual stimuli such as White's effect, which had been believed to defy filter-based explanations. Unlike competing explanations such as anchoring theory, filling-in, edge-integration, or layer decomposition, the spatial filtering approach embodied by the ODOG model readily accounts for the often overlooked but ubiquitous gradient structure of induction which, while most striking in grating induction, also occurs within the test fields of classical simultaneous brightness contrast and the White stimulus. Also, because the ODOG model does not require defined regions of interest, it is generalizable to any stimulus, including natural images. The ODOG model has motivated other researchers to develop modified versions (LODOG and FLODOG), and has served as an important counterweight and proof of concept to constrain high-level theories which rely on less well understood or justified mechanisms such as unconscious inference, transparency, perceptual grouping, and layer decomposition. Here we provide a brief but comprehensive description of the ODOG model as it has been implemented since 1999, as well as working Mathematica (Wolfram, Inc.) notebooks which users can employ to generate ODOG model predictions for their own stimuli.

Development of the adaptive music perception test.

Despite vast amounts of research examining the influence of hearing loss on speech perception, comparatively little is known about its influence on music perception. No standardized test exists to quantify music perception of hearing-impaired (HI) persons in a clinically practical manner. This study presents the Adaptive Music Perception (AMP) test as a tool to assess important aspects of music perception with hearing loss. A computer-driven test was developed to determine the discrimination thresholds of 10 low-level physical dimensions (e.g., duration, level) in the context of perceptual judgments about musical dimensions: meter, harmony, melody, and timbre. In the meter test, the listener is asked to judge whether a tone sequence is duple or triple in meter. The harmony test requires that the listener make judgments about the stability of the chord sequences. In the melody test, the listener must judge whether a comparison melody is the same as a standard melody when presented in transposition and in the context of a chordal accompaniment that serves as a mask. The timbre test requires that the listener determines which of two comparison tones is different in timbre from a standard tone (ABX design). Twenty-one HI participants and 19 normal-hearing (NH) participants were recruited to carry out the music tests. Participants were tested twice on separate occasions to evaluate test-retest reliability. The HI group had significantly higher discrimination thresholds than the NH group in 7 of the 10 low-level physical dimensions: frequency discrimination in the meter test, dissonance and intonation perception in the harmony test, melody-to-chord ratio for both melody types in the melody test, and the perception of brightness and spectral irregularity in the timbre test. Small but significant improvement between test and retest was observed in three dimensions: frequency discrimination (meter test), dissonance (harmony test), and attack length (timbre test). All other dimensions did not show a session effect. Test-retest reliability was poor (<0.6) for spectral irregularity (timbre test); acceptable (>0.6) for pitch and duration (meter test), dissonance and intonation (harmony test), and melody-to-chord ratio I and II (melody test); and excellent (>0.8) for level (meter test) and attack (timbre test). The AMP test revealed differences in a wide range of music perceptual abilities between NH and HI listeners. The recognition of meter was more difficult for HI listeners when the listening task was based on frequency discrimination. The HI group was less sensitive to changes in harmony and had more difficulties with distinguishing melodies in a background of music. In addition, the thresholds to discriminate timbre were significantly higher for the HI group in brightness and spectral irregularity dimensions. The AMP test can be used as a research tool to further investigate music perception with hearing aids and compare the benefit of different music processing strategies for the HI listener. Future testing will involve larger samples with the inclusion of hearing aided conditions allowing for the establishment of norms so that the test might be appropriate for use in clinical practice.

A Neurocomputational account of the role of contour facilitation in brightness perception.

A new filling-in model is proposed in order to account for challenging brightness illusions, where inducing background elements are spatially separated from the gray target such as dungeon, cube and grating illusions, bullseye display and ring patterns. This model implements the simple idea that neural response to low-contrast contour is enhanced (facilitated) by the presence of collinear or parallel high-contrast contours in its wider neighborhood. Contour facilitation is achieved via dendritic inhibition, which enables the computation of maximum function among inputs to the node. Recurrent application of maximum function leads to the propagation of the neural signal along collinear or parallel contour segments. When a strong global-contour signal is accompanied with a weak local-contour signal at the same location, conditions are met to produce brightness assimilation within the Filling-in Layer. Computer simulations showed that the model correctly predicts brightness appearance in all of the aforementioned illusions as well as in White's effect, Benary's cross, Todorović's illusion, checkerboard contrast, contrast-contrast illusion and various variations of the White's effect. The proposed model offers new insights on how geometric factors (contour colinearity or parallelism), together with contrast magnitude contribute to the brightness perception.

全視野における明るさ知覚特性

全視野における明るさ知覚特性

Spectral and photopic studies for high intensity discharge (HID) lamps

Outdoor lighting sources such as High Intensity Discharge lamps (HID) are common in these days. This research is focusing on the relation between the spectral power distribution and luminous efficiency function V (λ ), which describes the average spectral sensitivity of human visual perception of brightness. The most useable HID lamps inside Egyptian markets are high pressure mercury (HPM), high pressure sodium (HPS) and metal halide (MH). A set up based on single monochromator and integrating sphere for relative spectral power distribution and absolute luminous flux measurements are used, respectively. The accompanied standard uncertainties with the measurements are evaluated.

Spectral Sensitivity Modeling and Nighttime Scene Brightness Perception

ABSTRACTBrightness perception under different light sources is an important visual response, because it is related to perceptions of safety. A growing number of studies have been conducted to assess perceptions of scene brightness under light sources differing in spectral content, including results consistent with a role of melanopsin-containing, intrinsically photosensitive retinal ganglion cells in scene brightness. Data from recent studies of scene brightness perception at light levels experienced under nighttime driving conditions are used to compare different models of brightness perception. The data support a role of increased short-wavelength sensitivity for scene brightness perception and a provisional spectral sensitivity model that takes into account the possible influence of melanopsin-containing, intrinsically photoreceptive retinal ganglion cells is suggested as a basis for further investigation. The implications of such a model on brightness perception under several light sources used in transportation lighting are described.

Brightness induction and suprathreshold vision: effects of age and visual field.

A variety of visual capacities show significant age-related alterations. We assessed suprathreshold contrast and brightness perception across the lifespan in a large sample of healthy participants (N=155; 142) ranging in age from 16 to 80 years. Experiment 1 used a quadrature-phase motion cancelation technique (Blakeslee & McCourt, 2008) to measure canceling contrast (in central vision) for induced gratings at two temporal frequencies (1 Hz and 4 Hz) at two test field heights (0.5° or 2°×38.7°; 0.052 c/d). There was a significant age-related reduction in canceling contrast at 4 Hz, but not at 1 Hz. We find no age-related change in induction magnitude in the 1 Hz condition. We interpret the age-related decline in grating induction magnitude at 4 Hz to reflect a diminished capacity for inhibitory processing at higher temporal frequencies. In Experiment 2 participants adjusted the contrast of a matching grating (0.5° or 2°×38.7°; 0.052 c/d) to equal that of both real (30% contrast, 0.052 c/d) and induced (McCourt, 1982) standard gratings (100% inducing grating contrast; 0.052 c/d). Matching gratings appeared in the upper visual field (UVF) and test gratings appeared in the lower visual field (LVF), and vice versa, at eccentricities of ±7.5°. Average induction magnitude was invariant with age for both test field heights. There was a significant age-related reduction in perceived contrast of stimuli in the LVF versus UVF for both real and induced gratings.

Psychophysiological analysis of multidimensional structure of brightness perception in normal and altered states of consciousness

Psychophysiological analysis of multidimensional structure of brightness perception in normal and altered states of consciousness

Ray of Hope

Does bright lighting seem more desirable when people feel hopeless? Common parlance such as “ray of hope” depicts an association between hope and the perception of brightness. Building on research in embodied cognition and conceptual metaphor, we examined whether incidental emotion of hopelessness can affect brightness perception, which may influence people’s preference for lighting. Across four studies, we found that people who feel hopeless judge the environment to be darker (Study 1). As a consequence, hopeless people expressed a greater desire for ambient brightness and higher wattage light bulbs (Studies 2 and 3). Study 4 showed the reversal of the effect—being in a dimmer (vs. brighter) room induces greater hopelessness toward the perceived job search prospects. Taken together, these results suggest that hopeless feeling seems to bias people’s perceptual judgment of ambient brightness, which may potentially impact their electricity consumption.

Light modulation of human sleep depends on a polymorphism in the clock gene Period3

Non-image-forming (NIF) responses to light powerfully modulate human physiology. However, it remains scarcely understood how NIF responses to light modulate human sleep and its EEG hallmarks, and if there are differences across individuals. Here we investigated NIF responses to light on sleep in individuals genotyped for the PERIOD3 (PER3) variable-number tandem-repeat (VNTR) polymorphism. Eighteen healthy young men (20–28 years; mean±SEM: 25.9±1.2) homozygous for the PER3 polymorphism were matched by age, body-mass index, and ethnicity. The study protocol comprised a balanced cross-over design during the winter, during which participants were exposed to either light of 40lx at 6500K (blue-enriched) or light at 2500K (non-blue enriched), during 2h in the evening. Compared to light at 2500K, light at 6500K induced a significant increase in all-night NREM sleep slow-wave activity (SWA: 1.0–4.5Hz) in the occipital cortex for PER35/5 individuals, but not for PER34/4 volunteers. Dynamics of SWA across sleep cycles revealed increased occipital NREM sleep SWA for virtuallyall sleep episode only for PER35/5 individuals. Furthermore, they experienced light at 6500K as significantly brighter. Intriguingly, this subjective perception of brightness significantly predicted their increased occipital SWA throughout the sleep episode. Our data indicate that humans homozygous for the PER35/5 allele are more sensitive to NIF light effects, as indexed by specific changes in sleep EEG activity. Ultimately, individual differences in NIF light responses on sleep may depend on a clock gene polymorphism involved in sleep–wake regulation.

Field study of office worker responses to fluorescent lighting of different CCT and lumen output

A field study was performed to examine the effects of correlated color temperature (CCT) and lumen output of fluorescent lighting on office occupants' visual comfort, brightness perception, satisfaction, and self-reported productivity. Twenty-six participants were recruited (mean age = 38.8 years; age range = 23–55 years). Ten of them had daylight access in their personal work areas. Four lamp types were selected to create luminous conditions organized as a 2 × 2 factorial design, comprising two levels of CCT (i.e., 3500 and 5000 K) and lumen output (i.e., 2330 and ≈3000 lm). Each condition lasted two weeks. Under each condition, participants adapted during the first week. During the second week they completed ecological momentary assessments (EMAs) three times daily using smart phones. Two of the daily EMAs included questions about lighting. Participants also completed a web-based survey on the last day of each condition. The results from the EMA (60.0% response rate) and web-based (77.2% response rate) surveys were generally consistent, indicating that CCT significantly affected spatial brightness perception, visual comfort, satisfaction, and self-reported productivity. The luminous conditions at 5000 K (visually cooler) were rated to be brighter than those at 3500 K (visually warmer), especially when higher lumen output was in place. However, the increase in spatial brightness perception came with lower satisfaction, worse visual comfort, and worse self-reported productivity. The conditions at 5000 K were judged to be too cool, especially for those who had daylight in their work areas. The results of this study do not support the spectrally enhanced lighting (SEL) method advocated by the U.S. Department of Energy (DOE) as an energy savings strategy. Even when higher CCT resulted in higher spatial brightness perception, occupants' visual comfort and satisfaction were compromised.

Does Recalling Moral Behavior Change the Perception of Brightness?

Banerjee, Chatterjee, and Sinha (2012) recently reported that recalling unethical behavior led participants to see the room as darker and to desire more light-emitting products (e.g., a flashlight) compared to recalling ethical behavior. We replicated the methods of these two original studies with four high-powered replication studies (two online and two in the laboratory). Our results did not differ significantly from zero, 9 out of 10 of the effects were significantly smaller than the originally reported effects, and the effects were not consistently moderated by individual difference measures of potential discrepancies between the original and the replication samples. A meta-analysis that includes both the original and replication effects of moral recall on perceptions of brightness find a small, marginally significant effect (d = 0.14 CL95 −0.002 to 0.28). A meta-analysis that includes both the original and replication effects of moral recall on preferences for light-emitting products finds a small effect that did not differ from zero (d = 0.13 CL95 −0.04 to 0.29).

Brightness perception of white LED lights with different correlated colour temperatures

Various luminous environments can be created by utilizing light emitting diode (LED) lights which can be easily controlled with diverse illuminance and correlated colour temperature (CCT) levels. Implementation of such luminous environments could affect occupants’ perceptions. This study aim to identify subjective brightness perception of young healthy female and male students being exposed to different CCT conditions of LED lights in lecture room environment. To measure brightness perception, three subjective evaluations were conducted. First, brightness perception in different CCTs was compared under single CCT LED lights. Second, a single CCT of LED light was compared to the same CCT under mixed CCTs. Third, different mixing methods for a particular CCT were applied to mixed CCTs of LED lights. The results of the first test showed that the subjects perceived the environmental space to be brighter when exposed to a higher CCT with the same illuminance level. The second experiment showed that LED lights with mixed CCTs are relatively superior to LED lights with a single CCT in terms of brightness perception under the same illuminance level. The third experiment illustrated that the subjects would feel their environment as brighter when exposed to higher CCT and/or with a larger proportion of high CCT. The selections and mixing among different CCTs for classroom design can be determined based on the results of this study where brightness perception is important.

Color Preference under LEDs with Diminished Yellow Emission

A psychophysical experiment was conducted to investigate brightness perception and color preference under illumination from typical 3000 K blue-pumped light emitting diode (LED) A19 lamps (BP-LED) and 3000 K blue-pumped LED A19 lamps with diminished yellow emission (YD-LED). Eighty-seven participants between 19 and 25 years completed brightness matching and preference comparisons between two full-size side-by-side rooms that contained chromatic objects and still life arrangements, with one lamp type in each room. Participants had higher overall preference to the room illuminated by YD-LED. Specifically, red, green, orange, and wood objects were preferred under YD-LED; no preference was found for neutral, yellow, and blue objects between the two lamp types. The words saturated, vivid, vibrant, pleasant, inviting, colorful, stand-out, distinct, appealing, and comfortable were reported as reasons for the color preference under YD-LED; dull, dead, and fade were used by participants to describe the lower color preference under BP-LED. Skin tone preference under the illumination of these two lamp types was significantly different between Asian (n = 32) and Caucasian (n = 52) participants. Caucasians evaluated their own skin tone more favorably under YD-LED, with the average assessment that skin appeared healthy and colorful under YD-LED but grey and pale under BP-LED. No preference between the two lamps was found among Asians for their skin tone, though some Asians thought YD-LED rendered their skin too red and odd. Many existing measures of color preference and gamut were able to predict the higher overall preference to YD-LED, but they could not predict the preference of specific colors or for ethnic groups. The higher saturation and preference for red and green colors under YD-LED illumination is consistent with the higher red–green opponent signal provided by YD-LED. Coupled with several past studies, the spectral region around 570–580 nm appears to be deleterious to color and brightness perception.

Space Brightness Evaluation for Day-Lit Offices

To promote energy saving for office lighting, effective utilization of daylight illumination is necessary. It is very important to evaluate the brightness of a room taht is illuminated by both daylight and ceiling lamps. In this case, even if the average horizontal illuminance is kept constant, it is difficult to estimate the brightness perception of the room because of the very high intensity of daylight and the uneven distribution of light flux. In this paper, we investigated the effect of window size and intensity of daylight on the brightness perception of an office room with a window on one side. We examined the brightness perception and expressed it as a function of average horizontal illuminance attributed to the daylight and to the ceiling lamps.

Influence of Spectral Power Distribution on Scene Brightness at Different Light Levels

ABSTRACTExterior lighting has multiple objectives. Brightness perception is a relevant parameter for outdoor lighting because it is correlated with perceptions of safety and security. Understanding the influence of the spectral characteristics of lighting to scene brightness perception is important in order to devise exterior lighting specifications that support perceptions of safety and security in exterior lighted environments, as well as to optimize light source technologies to account for these factors. A study of scene brightness perception under different light levels and spectral power distributions was conducted to assess whether scene brightness perception exhibited increased short-wavelength spectral sensitivity as a function of increasing light level. The results confirm that a successful model of spectral sensitivity for scene brightness perception should incorporate a shift in short-wavelength sensitivity like the one investigated in the present study.

Inter-trial effect in luminance processing revealed by Magnetoencephalography

In this study, we examined whether luminance processing in the human visual system would exhibit any history effect (i.e., inter-trial modulation) in psychophysical and magnetoencephalographic experiments. A disk was presented against a black background at various luminance levels in a randomized order. During the MEG recording, participants were instructed to rate the brightness of the disk (magnitude estimation) and to report it aloud during inter-stimulus interval. The MEG results showed that the neuromagnetic activation around 200-220 ms after the stimulus onset in the left occipito-temporal regions at a given trial was weaker when the disk luminance in the immediately prior trial was higher. An inverse inter-trial effect was also observed in the psychophysical experiment. These findings suggest that the neuromagnetic activity reflects the inter-trial modulation of luminance processing that correlates with the subjective perception of brightness.

Cilioretinal artery and central retinal vein occlusion after sildenafil use

It's reported that sildenafil may cause non-arteritic anterior ischaemic optic neuropathy and transient changes in perception of colour hue or brightness.1 We report a case of cilioretinal artery and central...

Perceptual brightness decisions do not use a difference model

Perceptual brightness decisions do not use a difference model