Color contrast adaptation and compensation in color deficiencies.

Anomalous trichromacy (AT) results from a reduced spectral separation between the L and M cone photopigments. This leads to smaller differential responses in the L and M cones and thus lower sensitivity to the colors signaled by the LvsM difference. Despite this, for stimuli above threshold, many color-anomalous observers report color experiences that resemble those of color-normal individuals, suggesting some form of perceptual compensation for their sensitivity losses.

Sensitivity to the number of colors in textures defined by luminance and chromatic contrast.

Changes in the mean or variance of a color ensemble can be readily detected, but how sensitive are observers to the actual number of colors defining the array? Discriminating changes in the number of unique hues or saturations in the set becomes difficult when the set reaches four or more levels [J. Opt. Soc.

Color number and texture perception.

The color gamut of visual scenes can encompass a multitude of hues, but how many distinct hues are individuals aware of? We examined this question in the context of texture perception, with a grid of stimuli composed of random colors chosen from color sets varying from two to six different hues or saturations. In a behavioral experiment, participants had to discriminate between differences in the number of hues present by identifying which of four color grids included a larger number of different colors. Color number discrimination was also assessed neurally, using electroencephalogram (EEG) frequency tagging, wherein a texture with an extra hue was shown as an "oddball," once per second, in a stream of textures presented at six images per second.

Achromatic loci in normal and anomalous trichromats.

The stimuli that appear achromatic anchor color space and exhibit multiple properties that reflect an alignment of color vision with spectral characteristics of the chromatic environment. We examined how well this alignment is preserved in individuals with anomalous trichromacy. Observers viewed stimuli spanning a range of chromaticities and luminance contrasts relative to a nominal gray background of varying luminance, and classified the stimuli as achromatic (white or gray) or chromatic (one of eight color terms).

Visual search for warm and cool colors.

Warm versus cool colors are considered a fundamental aspect of color experience, yet the basis for this distinction remains poorly understood. Recently, we found that the warm-cool dimension closely aligns with sensitivity biases implicit in uniform color spaces [J. Vis.

Correcting images for individual differences in color appearance.

Individual differences are a prominent feature of normal color vision and range from variations in sensitivity to perception and color naming. Corrections for differences in spectral sensitivity are common, and there is growing interest in calibrating displays for the sensitivity of an individual observer. In contrast, few studies have explored calibrations for aspects of color appearance.

Warm versus cool colors and their relation to color perception.

The distinction between warm and cool colors is widely considered a fundamental aspect of human color experience, but whether it reflects properties of color perception or color associations remains unclear. We examined how the warm-cool division is related to perceptual landmarks of color coding and color appearance. Observers made warm-cool ratings for 36 hue angles at three luminance levels and also estimated the angles for their unique (e.

Changes in Reader Performance During Sequential Reading of Breast Cancer Screening Digital Breast Tomosynthesis Examinations.

Background Studies suggest that readers experience perceptual adaptation when interpreting batched screening mammograms, which may serve as a mechanism for improved performance. Purpose To analyze clinical digital breast tomosynthesis (DBT) screening data to evaluate changes in reader performance during sequential batch reading. Materials and Methods This observational retrospective study used data from the radiology information system collected for screening DBT examinations performed from January 2018 to December 2019.

Automatic, Early Color-Specific Neural Responses to Object Color Knowledge.

Some familiar objects are associated with specific colors, e.g., rubber ducks with yellow.

Calibrating Vision: Concepts and Questions.

The idea that visual coding and perception are shaped by experience and adjust to changes in the environment or the observer is universally recognized as a cornerstone of visual processing, yet the functions and processes mediating these calibrations remain in many ways poorly understood. In this article we review a number of facets and issues surrounding the general notion of calibration, with a focus on plasticity within the encoding and representational stages of visual processing. These include how many types of calibrations there are - and how we decide; how plasticity for encoding is intertwined with other principles of sensory coding; how it is instantiated at the level of the dynamic networks mediating vision; how it varies with development or between individuals; and the factors that may limit the form or degree of the adjustments.

Using equiluminance settings to estimate the cardinal chromatic directions for individuals.

Color information is processed by the retina and lateral geniculate along principal dimensions known as the cardinal directions of color space. Normal differences in spectral sensitivity can impact the stimulus directions that isolate these axes for individual observers and can arise from variation in lens and macular pigment density, photopigment opsins, photoreceptor optical density, and relative cone numbers. Some of these factors that influence the chromatic cardinal axes also impact luminance sensitivity.

Gaining the system: limits to compensating color deficiencies through post-receptoral gain changes.

Color percepts of anomalous trichromats are often more similar to normal trichromats than predicted from their receptor spectral sensitivities, suggesting that post-receptoral mechanisms can compensate for chromatic losses. The basis for these adjustments and the extent to which they could discount the deficiency are poorly understood. We modeled the patterns of compensation that might result from increasing the gains in post-receptoral neurons to offset their weakened inputs.

Visual adaptation to medical images: a comparison of digital mammography and tomosynthesis.

Purpose: Radiologists and other image readers spend prolonged periods inspecting medical images. The visual system can rapidly adapt or adjust sensitivity to the images that an observer is currently viewing, and previous studies have demonstrated that this can lead to pronounced changes in the perception of mammogram images. We compared these adaptation effects for images from different imaging modalities to explore both general and modality-specific consequences of adaptation in medical image perception.

Fundamentally different representations of color and motion revealed by individual differences in perceptual scaling.

The coordinate frames for color and motion are often defined by three dimensions (e.g., responses from the three types of human cone photoreceptors for color and the three dimensions of space for motion).

Temporal dynamics of face adaptation.

The appearance of a face can be strongly affected by adaptation to faces seen previously. A number of studies have examined the time course of these aftereffects, but the integration time over which adaptation pools signals to control the adaptation state remains uncertain. Here we examined the effects of temporal frequency on face gender aftereffects induced by a pair of faces alternating between the two genders to assess when the aftereffects were pooled over successive faces versus driven by the last face seen.

Adapting to an enhanced color gamut - implications for color vision and color deficiencies.

One strategy for aiding color deficiencies is to use three narrow passbands to filter the light spectrum to increase the saturation of colors. This filtering is analogous to the narrow emission bands used in wide gamut lighting or displays. We examined how perception adapts to the greater color gamut area produced by such devices, testing color-normal observers and simulated environments.

Using Smooth Metamers to Estimate Color Appearance Metrics for Diverse Color-Normal Observers.

Color-normal subjects sometimes disagree about metameric matches involving highly structured SPDs, because their cone fundamentals differ slightly, but non-negligibly. This has significant implications for the design of light sources and displays, so it should be estimated. We propose a broadly applicable estimation method based on a simple adaptive "front-end" interface that can be used with any selected standard color appearance model.

ENHANCED PERIPHERAL FACE PROCESSING IN DEAF INDIVIDUALS.

Studies of compensatory changes in visual functions in response to auditory loss have shown that enhancements tend to be restricted to the processing of specific visual features, such as motion in the periphery. Previous studies have also shown that deaf individuals can show greater face processing abilities in the central visual field. Enhancements in the processing of peripheral stimuli are thought to arise from a lack of auditory input and a subsequent increase in the allocation of attentional resources to peripheral locations, while enhancements in face processing abilities are thought to be driven by experience with ASL and not necessarily hearing loss.

Contrast Adaptation in Face Perception Revealed Through EEG and Behavior.

Exposure to a face can produce biases in the perception of subsequent faces. Typically, these face aftereffects are studied by adapting to an individual face or category (e.g.

Color appearance model incorporating contrast adaptation - implications for individual differences in color vision.

Color appearance models use standard color matching functions to derive colorimetric information from spectral radiometric measurements of a visual environment, and they process that information to predict color perceptual attributes such as hue, chroma and lightness. That processing is usually done by equations with fixed numerical coefficients that were predetermined to yield optimal agreement for a given standard observer. Here we address the well-known fact that, among color-normal observers, there are significant differences of color matching functions.

Varying Stimulus Duration Reveals Consistent Neural Activity and Behavior for Human Face Individuation.

Establishing consistent relationships between neural activity and behavior is a challenge in human cognitive neuroscience research. We addressed this issue using variable time constraints in an oddball frequency-sweep design for visual discrimination of complex images (face exemplars). Sixteen participants viewed sequences of ascending presentation durations, from 25 to 333 ms (40-3 Hz stimulation rate) while their electroencephalogram (EEG) was recorded.