Sophie M Wuerger

University of Liverpool | UoL · Department of Psychological Sciences

Until recently induced gamma-band activity (GBA) was considered a neural marker of cortical object representation. However, induced GBA in the electroencephalogram (EEG) is susceptible to artifacts caused by miniature fixational saccades. Recent studies have demonstrated that fixational saccades also reflect high-level representational processes. D...

IT IS WELL KNOWN THAT THE PERIPHERAL VISUAL SYSTEM DECLINES WITH AGE: the yellowing of the lens causes a selective reduction of short-wavelength light and sensitivity losses occur in the cone receptor mechanisms. At the same time, our subjective experience of colour does not change with age. The main purpose of this large-scale study (n = 185) cove...

We use multivoxel pattern analysis (MVPA) to study the spatial clustering of color-selective neurons in the human brain. Our main objective was to investigate whether MVPA reveals the spatial arrangements of color-selective neurons in human primary visual cortex (V1). We measured the distributed fMRI activation patterns for different color stimuli...

Our aim was to characterise the chromatic mechanisms that yield the four unique hues: red, green, yellow and blue. We measured the null planes for all four unique hues and report the following two main results. (1) We confirm that three chromatic mechanisms are required to account for the four unique hues. These three chromatic mechanisms do not co...

A vital heuristic used when making judgements on whether audio-visual signals arise from the same event, is the temporal coincidence of the respective signals. Previous research has highlighted a process, whereby the perception of simultaneity rapidly recalibrates to account for differences in the physical temporal offsets of stimuli. The current p...

The contrast sensitivity function (CSF) is a fundamental visual model explaining our ability to detect small contrast patterns. CSFs found many applications in engineering, where they can be used to optimize a design for perceptual limits. To serve such a purpose, CSFs must explain possibly a complete set of stimulus parameters, such as spatial and...

During the olfactory perception process, our olfactory receptors are thought to recognize specific chemical features. These features may contribute towards explaining our crossmodal perception. The physicochemical features of odors can be extracted using an array of gas sensors, also known as an electronic nose. The present study investigates the r...

The idea of colour opponency maintains that colour vision arises through the comparison of two chromatic mechanisms, red versus green and yellow versus blue. The four unique hues, red, green, blue, and yellow, are assumed to appear at the null points of these the two chromatic systems. Here we hypothesise that, if unique hues represent a tractable...

When designing multisensorial experiences, robustly predicting the crossmodal perception of olfactory stimuli is a critical factor. We investigate the possibility of predicting olfactory crossmodal correspondences using the underlying physicochemical features. An electronic nose was tuned to the crossmodal perceptual axis of olfaction and was used...

Olfaction is ingrained into the fabric of our daily lives and constitutes an integral part of our perceptual reality. Within this reality, there are crossmodal interactions and sensory expectations; understanding how olfaction interacts with other sensory modalities is crucial for augmenting interactive experiences with more advanced multisensorial...

Predicting olfactory perception with an electronic nose can aid in the design and evaluation of olfactory-based experiences. We investigate whether the human perception of odours can be predicted outside the bounds of perceived pleasantness and semantic descriptors. We tuned an electronic nose to predict an odour's colour in the CIELAB colour space...

Predicting olfactory perception with an electronic nose can aid in the design and evaluation of olfactory-based experiences. We investigate whether the human perception of odours can be predicted outside the bounds of perceived pleasantness and semantic descriptors. We tuned an electronic nose to predict an odour's colour in the CIELAB colour space...

The idea of colour opponency maintains that colour vision arises through the comparison of two chromatic mechanisms, red versus green (RG) and yellow versus blue (YB). The four unique hues, red, green, blue, and yellow, are assumed to appear at the null points of these the two chromatic systems. However, whether unique hues have a distinct signatur...

The temporal binding window (TBW), which reflects the range of temporal offsets in which audiovisual stimuli are combined to form a singular percept, can be reduced through training. Our research aimed to investigate whether training-induced reductions in TBW size transfer across stimulus intensities. A total of 32 observers performed simultaneity...

The main ingredient of sunless tanning products is dihydroxyacetone (DHA). DHA reacts with the protein and amino acid composition in the surface layers of the skin, producing melanoidins, which changes the skin colour, imitating natural skin tan caused by melanin. The purpose of this study was to characterise DHA-induced skin colour changes and to...

We investigated spatio-chromatic contrast sensitivity in both younger and older color-normal observers. We tested how the adapting light level affected the contrast sensitivity and whether there was a differential age-related change in sensitivity. Contrast sensitivity was measured along three directions in colour space (achromatic, red-green, yell...

The main ingredient of sunless tanning products is dihydroxyacetone (DHA). DHA reacts with the protein and amino acid composition in the surface layers of the skin, producing melanoidins, which changes the skin colour, imitating natural skin tan caused by melanin. The purpose of this study was to characterise DHA-induced skin colour changes and to...

We model color contrast sensitivity for Gabor patches as a function of spatial frequency, luminance and chromacity of the background, modulation direction in the color space and stimulus size. To fit the model parameters, we combine the data from five independent datasets, which let us make predictions for background luminance levels between 0.0002...

We investigated spatio-chromatic contrast sensitivity in both younger and older color-normal observers. We tested how the adapting light level affected the contrast sensitivity and whether there was a differential age-related change in sensitivity. Contrast sensitivity was measured along three directions in colour space (achromatic, red-green, yell...

The goal of this research is to generate high quality chromatic Contrast Sensitivity Function (CSF) over a wide range of spatial frequencies from 0.06 to 3.84 cycles per degree (cpd) surrounding 5 CIE proposed colour centres (white, red, yellow, green and blue) to study colour difference. At each centre, 6 colour directions at each of 7 frequencies...

The purpose of our study was to investigate the difference in spatio-chromatic contrast sensitivity between younger and older colour-normal observers. We were particularly interested in how the adapting light level affected the contrast sensitivity and whether there was a differential age-related change in sensitivity. Contrast sensitivity was meas...

Contrast sensitivity functions (CSFs) characterize the sensitivity of the human visual system at different spatial frequencies. However, little is known about CSFs at luminances above 1000 cd/m ² , especially for color. Here, we measured contrast sensitivities at background luminances from 0.02 cd/m ² to 7000 cd/m ² and for three color directions (...

Contrast sensitivity functions (CSFs) characterize the sensitivity of the human visual system at different spatial scales, but little is known as to how contrast sensitivity for achromatic and chromatic stimuli changes from a mesopic to a highly photopic range reflecting outdoor illumination levels. The purpose of our study was to further character...

We estimated Trump’s skin colour from 70 internet images and also from the “twitter tan line” image (February 8, 2020; Twitter). We then compared the estimated skin colours with two existing data sets of skin colours: the range of skin tans that occur naturally in the Caucasian population and the range skin colours brought about by a sunless tan. W...

The conference saw the participation of over 900 fellow vision scientists coming from all around the world; the vast majority of them actively participated, allowing us to offer an outstanding scientific program. We hosted more than 500 posters during the innovative ‘Poster day’.

Despite the importance of the appearance of human skin for theoretical and practical purposes, little is known about visual sensitivity to subtle skin-tone changes, and whether the human visual system is indeed optimized to discern skin-color changes that confer some evolutionary advantage. Here, we report discrimination thresholds in a three-dimen...

Abstract Background/aims The ability to extract depth from disparity may be hindered under fusional stress, as alignment of the eyes may be more difficult to maintain consistently. Therefore we aim to determine the effect of fusional demand on stereoacuity in individuals with no known binocular vision impairments. Methods A novel static and dynamic...

Recent progress in additive manufacturing technology has improved the realistic colour reproduction of 3D facial prostheses with computational optimisation of skin colour profiles. The colour appearance of the prosthetic surface depends on both the spectral characteristics of the surfaces and the scene illumination. Considering everyday environment...

This study aimed to investigate the variability of skin colour measurements for two kinds of extensively used instruments, telespectroradiometers (TSR) and spectrophotometers. A Konica Minolta CM700d spectrophotometer and a PhotoResearch PR650 telespectroradiometer were used to measure the forehead and the cheekbone of 11 subjects. The variability...

Skin color provides essential information about an individual's health condition and emotion. Additive manufacturing of human skin has been developed markedly in recent years along with increasing demands for clinical and medical applications. It is therefore critical to achieve precise color reproduction of facial skin and constant color appearanc...

Skin color provides essential information about an individual’s health condition and emotion. Additive manufacturing of human skin has been developed markedly in recent years along with increasing demands for clinical and medical applications. It is therefore critical to achieve precise color reproduction of facial skin and constant color appearanc...

PurposeThe purpose of the study was to study the effect of an organic light-emitting diode sleep mask on daytime alertness, wellbeing, and retinal structure/function in healthy volunteers and in diabetic macular oedema (DMO).Patients and methodsHealthy volunteers in two groups, 18-30 yrs (A), 50-70 yrs (B) and people with DMO (C) wore masks (504 nm...

Human skin colour information is important for the cosmetic industries and hospitals to develop a skin product and suggest an appropriate treatment. Human skin has multi-layered structures with non-flat surface and the colour of the human skin is unevenly distributed over the body. It is difficult to get skin colour information both exhaustively an...

Two experiments were conducted for collecting skin database at the Universities of Liverpool and Leeds (UK), and Zhejiang University (China). Overall, 235 subjects from 4 different skin groups (Caucasians, Chinese, South Asian and Dark) were recruited. Each was measured using 4 types of colour measuring methods (tele-spectroradiometer, spectrophoto...

We review the evidence, from different data sets collected under different viewing conditions, illumination sources, and measurement protocols, for intra- and interobserver variability in generic subjective white-point settings along the daylight locus. By generic subjective white-point we mean the subjective white-point independent of the specific...

Aim: Subjects with no clinically measurable stereoacuity report compelling ‘pop-out’ depth effects when viewing a 3D stereoscopic video. The purpose of this study was to systematically investigate the effectiveness of static and dynamic stereoscopic stimuli, by isolating cues to depth present in stereoscopic 3D entertainment media. Methods: Stereo...

In this chapter, using colour 3D printing technology, a 3D colour image reproduction system is detailed for the semi-automated and accurate additive manufacturing of facial soft tissue prostheses. A protocol for 3D colour image reproduction was designed based on the six steps of processing. For this specific application, protocols for each sub‐ pro...

Purpose: A clinical diagnosis of stereoblindness does not necessarily preclude compelling depth perception. Qualitative observations suggest that this may be due to the dynamic nature of the stimuli. The purpose of this study was to systematically investigate the effectiveness of static and dynamic stereoscopic stimuli. Methods: Stereoscopic sti...

A improved spectral reflectance reconstruction method is developed to transform camera RGB to spectral reflectance for skin images. Rather than using conventional direct or two-step processes, we transform camera RGB to skin reflectance directly using a principal component analysis (PCA) approach. The novelty in our direct method (RGB to spectra) i...

Background: Accurate skin colour measurements are important for numerous medical applications including the diagnosis and treatment of cutaneous disorders and the provision of maxillofacial soft tissue prostheses. Methods: In this study, we obtained accurate skin colour measurements from four different ethnic groups (Caucasian, Chinese, Kurdish,...

Accurate spectral measurements of facial skin are important for numerous medical applications including the diagnosis and treatment of cutaneous disorders and the provision of maxillofacial soft tissue prostheses. In this study we obtained calibrated facial and body skin spectra (forehead, cheek, neck) from two ethnic groups (Caucasian and Oriental...

Human skin colour measurements from four ethnic groups including 188 subjects were accumulated. Five to ten locations of each subject were measured by using two different instruments, a tele-spectroradiometer and a spectrophotometer. Three repeated measurements were accumulated for each location. Repeatability of the measurements at different locat...

Motion is represented by low-level signals, such as size-expansion in vision or loudness changes in the auditory modality. The visual and auditory signals from the same object or event may be integrated and facilitate detection. We explored behavioural and electrophysiological correlates of congruent and incongruent audio-visual depth motion in con...

The aim of this study was to estimate discrimination thresholds in 3-D colour space for images of skin patches from two ethnicities - Caucasian and Asian; with the observer fully immersed in three different illumination conditions - dark, daylight and cool-white-fluorescent. In the illuminated conditions, the patches were presented in an 'object mo...

Experimental primate glaucoma demonstrates that the retinal ganglion cell (RGC) loss is associated with atrophies in the lateral geniculate nucleus (LGN) and the primary visual cortex (V1). The purpose of our study was to determine whether, in glaucoma patients, selective behavioural deficits in the three main visual pathways (magnocellular, parvoc...

A method for estimating the non-linear gamma transfer function of liquid-crystal displays (LCD) without the need of a photometric measurement device was described by Xiao et al [1]. It relies on observer’s judgments of visual luminance by presenting eight half-tone patterns with luminances from 1/9 to 8/9 of the maximum value of each colour channel...

Principal component analyses (PCA) were conducted for skin spectral reflectance of a new skin colour database. Results for skin colours from different ethnic groups were analysed and reflectance re-construction based on first three components obtained by PCA were investigated. Significant differences in the derived principal components for the thre...

In this study, Swedish Natural Color System (NCS) unique hue data were used to evaluate the performance of unique hue predictions by the CIECAM02 colour appearance model. The colour appearance of 108 NCS unique hue stimuli was predicted using CIECAM02, and their distributions were represented in a CIECAM02 ac–bc chromatic diagram. The best-fitting...

The purpose of our experiments was to investigate the effect of interaxial camera separation on the perceived shape and viewing comfort of 3D images. Horizontal Image Translation (HIT) and interaxial distance were altered together. Following Banks et al (2009), our stimuli were simple stereoscopic hinges and we measured the perceived angle as a fun...

An achromatic stimulus is defined as a patch of light that is devoid of any hue. This is usually achieved by asking observers to adjust the stimulus such that it looks neither red nor green and at the same time neither yellow nor blue. Despite the theoretical and practical importance of the achromatic locus, little is known about the variability in...

In the early twentieth century, the Bauhaus revolutionized art and design by using simple colors and forms. Wassily Kandinsky was especially interested in the relationship of these two visual attributes and postulated a fundamental correspondence between color and form: yellow triangle, red square and blue circle. Subsequent empirical studies used...

It is well known that the peripheral visual system declines with age: the yellowing of the lens causes a selective reduction of short-wavelength light and sensitivity losses occur in the cone receptor mechanisms. At the same time, our subjective experience of colour does not change with age. The main purpose of this large-scale study (n=185) coveri...

An extensive network of cortical areas is involved in multisensory object and action recognition. This network draws on inferior frontal, posterior temporal, and parietal areas; activity is modulated by familiarity and the semantic congruency of auditory and visual component signals even if semantic incongruences are created by combining visual and...

Spectra, cone fundamentals and lens model. (a) The Spectral radiance distribution of the CRT phosphors b) The Stockman-Sharpe cone fundamentals used to obtain the lens predictions (c) Lens transmission as a function of wavelength, based on the Pokorny et al. lens model. Each line indicates the transmission of a particular age group, from 20 to 80 y...

Hue settings for the lower and the upper age group under D65. Details as in Figure 4 (a) Observed unique hue settings for D65 are shown as circles in Boynton-MacLeod chromaticity diagram for the younger age group (<30 y.o.a). Symbol size is proportional to the number of observations per data point. Dotted lines indicate the observed unique hue line...

Hue settings for the lower and the upper age group under CWF. Details as in Figure 4. (a) Observed unique hue settings under CWF are shown as circles in Boynton-MacLeod chromaticity diagram for the younger age group (<30 y.o.a). Symbol size is proportional to the number of observations per data point. Dotted lines indicate the observed unique hue l...

Unique hue settings of 185 observers under three room-lighting conditions were used to evaluate the accuracy of full and mixed chromatic adaptation transform models of CIECAM02 in terms of unique hue reproduction. Perceptual hue shifts in CIECAM02 were evaluated for both models with no clear difference using the current Commission Inter-nationale d...