Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Previous studies have identified differences in sensitivity characteristics between color discrimination and perception of suprathreshold color differences. However, it remains highly unclear how color difference sensitivity changes with increasing magnitudes of color difference along various color hues. This study aimed to quantify the sensitivity transition across various magnitudes of color differences and uncover the underlying mechanisms. Color discrimination sensitivities were measured using an adaptive staircase method for 32 isoluminant pedestal colors in the u'v' chromaticity diagram. For suprathreshold color differences, we employed the Maximum Likelihood Difference Scaling (MLDS) method to measure sensitivity to various color difference levels for the same 32 colors. Our findings confirmed the differences in sensitivity characteristics between discrimination and suprathreshold color difference perception. Furthermore, we observed increased sensitivities at many color category boundaries in suprathreshold color difference perception. By investigating the relation between the category effects and the color difference size levels through a model simulation, our findings suggest that the influence of color categories on the perception of color differences may become more pronounced as the magnitude of color differences increases.

DOI： 10.1038/s41598-024-64215-0

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Other Link： https://www.nature.com/articles/s41598-024-64215-0.pdf

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Perceptual learning is the improvement of perceptual performance after repeated practice on a perceptual task. Studies on perceptual learning in color vision are limited. In this study, we measured the impact of color discrimination repetitions at a specific base color on color perception for entire hues. Participants performed five sessions of color discrimination training (200 or 300 trials per session) over five days, at colors on either the negative or positive direction of the L-M color axis, based on group assignment. We administered three color perception assessments (unique hues, color category boundaries, and color appearance) before and after the sessions to evaluate perceptual changes after training. The results showed declines in color discrimination thresholds after training, as expected. Additionally, the training influenced outcomes across all three assessment types. After the training, the perceived color appearance changed near the trained color along the stimulus hue, and some of the unique hues and the color category boundaries moved significantly toward the trained color. These findings indicate that short-term repetitions of color discrimination training can alter color representations in the visual system, distorting color perception around the trained color.

DOI： 10.1038/s41598-024-60283-4

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Other Link： https://www.nature.com/articles/s41598-024-60283-4.pdf

Publisher：Association for Research in Vision and Ophthalmology (ARVO)  

DOI： 10.1167/jov.23.15.53

CiNii Research

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Publisher：Association for Research in Vision and Ophthalmology (ARVO)  

DOI： 10.1167/jov.23.15.56

CiNii Research

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Publishing type：Research paper (international conference proceedings)   Publisher：ACM  

DOI： 10.1145/3610542.3626145

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Other Link： https://dl.acm.org/doi/pdf/10.1145/3610542.3626145

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.visres.2022.108140

PubMed

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Language：English   Publishing type：Research paper (scientific journal)  

Previous studies have shown that information concerning object shape is important for the perception of translucency. This study aims to explore how the perception of semi-opaque objects is influenced by surface gloss. We varied specular roughness, specular amplitude, and the simulated direction of a light source used to illuminate a globally convex bumpy object. We found that perceived lightness and roughness increased as specular roughness was increased. Declines in perceived saturation were observed but were far smaller in magnitude with these increases in specular roughness. There were inverse correlations found between perceived gloss and perceived lightness, perceived transmittance and perceived saturation, and between perceived roughness and perceived gloss. Positive correlations were found between perceived transmittance and glossiness, and between perceived roughness and perceived lightness. These findings suggest that specular reflections influence the perception of transmittance and color attributes, and not just perceived gloss. We also performed follow-up modeling of image data to find that perceived saturation and lightness could be explained by the reliance on different image regions with greater chroma and lower lightness, respectively. We also found systematic effects of lighting direction on perceived transmittance that indicate there are complex perceptual interactions that require further consideration.

DOI： 10.1364/JOSAA.479972

PubMed

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1167/jov.23.3.1

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

In conventional psychophysical reverse correlation methods using white or pink noise, the luminance noise is added to every pixel. Thus, the image features correlated with perception are often biased toward local mean luminance. Furthermore, spatial frequencies and orientations are represented in the primary visual cortex, which forms the basis of various visual perception. In this study, we proposed a new reverse correlation method using noise that modulated the spatial frequency sub-band contrast and examined its properties in psychophysical experiments on facial skin lightness perception. In the experiment, we asked the observers to compare the perceived skin lightness in a paired comparison manner on face stimuli with increased or decreased spatial frequency sub-band contrasts at random spatial locations. The results showed that the contrasts in the eyes or irises were strongly and positively correlated with the perceived skin lightness in most sub-bands, demonstrating that the proposed method reiterated the findings of previous studies that the sparkle of the irises makes the skin appear lighter. Contrarily, the conventional reverse correlation method using pink noise images was applied to the skin lightness perception. The results indicated that only the local mean luminance in some skin regions, such as the forehead, was correlated with skin lightness perception. In summary, with the proposed method, we found some image features in the facial parts other than the skin mean luminance relevant to skin lightness perception, which are difficult to detect using the conventional method. They are considered complementary given that the proposed method and the conventional method extracted considerably different image features. It depends on the psychophysical tasks and stimuli which one is more appropriate.

DOI： 10.1016/j.visres.2022.108028

PubMed

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

Color adaptation is a phenomenon in which, after prolonged exposure to a specific color (i.e. adaptation color), the perceived color shifts to approximately the opposite color direction of the adaptation color. Color adaptation is strongly related to sensitivity changes in photoreceptors, such as von Kries adaptation and cone-opponent mechanisms. On the other hand, the perceptual contrast of colors (e.g. perceptual saturation of the red-green direction) decreases after adaptation to a stimulus with spatial and/or temporal color modulation along the color direction. This phenomenon is referred to as color contrast adaptation. Color contrast adaptation has been used to investigate the representation of colors in the visual system. In the present study, we measured color perception after color contrast adaptation to stimuli with temporal color modulations along complicated color loci in a luminance-chromaticity plane. We found that, after the observers adapted to color modulations with different chromaticities at higher, medium, and lower luminance (e.g. temporal alternations among red, green, and red, each at a different luminance level), the chromaticity corresponding to perceptual achromaticity (the achromatic point) shifted to the same color direction as the adaptation chromaticity in each test stimulus luminance. In contrast, this luminance dependence of the achromatic point shift was not observed after adaptation to color modulations with more complex luminance-chromaticity correspondences (e.g. alternating red, green, red, green, and red, at five luminance levels, respectively). In addition, the occurrence or nonoccurrence of the luminance-dependent achromatic point shift was qualitatively predicted using a noncardinal model composed of channels preferring intermediate color directions between the cardinal chromaticity and luminance axes. These results suggest that the noncardinal channels are involved in the luminance-dependent perceived color shift after adaptation.

DOI： 10.1167/jov.22.7.8

PubMed

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Language：Japanese   Publishing type：Research paper (scientific journal)  

J-GLOBAL

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

Abstract

Contrast sensitivity functions (CSFs) have been typically measured under persistent adaptation to a uniform background. However, this is an unusual situation, considering that visual scenes in our daily lives are typically filled by objects of various luminance levels in a wide dynamic range. We investigated the interactions between the luminance range of textured adapting background and test luminance (luminance of an immediate surround) to see how the contrast sensitivities adapt to background luminance distributions. The background was a random array of one‐dimensional lines, which had a maximum luminance range of approximately 1:520 000, and the test stimulus was a Gabor patch presented on an immediate uniform surround with various luminance levels. The carrier orientation of the Gabor patch was orthogonal to that of the background lines. In the results, the sensitivity was highest near the mean of background luminance, and the luminance range with the highest sensitivity became wider (i.e., the selectivity of sensitivity optimization weakened) as the background luminance range became larger. This sensitivity optimization was significant mainly in the lower spatial frequency. These results indicate that the overall contrast sensitivity is adjusted to the luminance range of the visual scene and the sensitivity optimization is more flexible in relatively lower spatial frequency.

DOI： 10.1002/col.22723

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Other Link： https://onlinelibrary.wiley.com/doi/pdf/10.1002/col.22723

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：東京 : 日本光学会  

CiNii Books

CiNii Research

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Other Link： https://ndlsearch.ndl.go.jp/books/R000000004-I031702703

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

It has been suggested that luminance edges in retinal images are potential cues for glossiness perception, particularly when the perception relies on low-luminance specular regions. However, a previous study has shown only statistical correlations between luminance edges and perceived glossiness, not their causal relations. Additionally, although specular components should be embedded at various spatial frequencies depending on the micro-roughness on the object surface, it is not well understood what spatial frequencies are essential for glossiness perception on objects with different micro-roughness. To address these issues, we examined the impact of a sub-band contrast enhancement on the perceived glossiness in the two conditions of stimuli: the Full condition where the stimulus had natural specular components and the Dark condition where it had specular components only in dark regions. Object images with various degrees of surface roughness were generated as stimuli, and their contrast was increased in various spatial-frequency sub-bands. The results indicate that the enhancement of the sub-band contrast can significantly increase perceived glossiness as expected. Furthermore, the effectiveness of each spatial frequency band depends on the surface roughness in the Full condition. However, effective spatial frequencies are constant at a middle spatial frequency regardless of the stimulus surface roughness in the Dark condition. These results suggest that, for glossiness perception, our visual system depends on specular-related information embedded in high spatial frequency components but may change the dependency on spatial frequency based on the surface luminance to be judged.

DOI： 10.3389/fpsyg.2021.625135

PubMed

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Language：English   Publishing type：Research paper (scientific journal)  

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Kansei Engineering  

There have been growing interests in clarifying perceptual mechanisms for different material features such as glossiness and transparency in recent years. In this study, we examined whether perceptual learning effects can be observed for material perceptions, and whether active conduct of material judgment tasks is important for the learning effects. The observers were divided into two groups; the glossiness group and the transparency group. The former observers repeated a glossiness discrimination task, while the latter observers repeated a transparency discrimination task for 10 days. We measured changes in correct response ratios and reaction times for discriminations of learned and unlearned material features between before and after the learning. In the results, in both learning groups, the reaction times for the learned material features were significantly shortened after the learning. These results suggest that the human visual system can increase glossiness and transparency discrimination performances by actively repeating material discrimination tasks.

DOI： 10.5057/jjske.tjske-d-18-00019

CiNii Research

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17H01809/

Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japanese Psychonomic Society  

<p>We investigated what visual artists learn during sketch training by comparing 3 groups (Experts, Trainees, and Novices). In 2 tasks (congruence detection and glossiness judgment), we manipulated the specular reflection component of bumpy glossy surface images by angular rotation and asked participants to compare original and modified versions. Effects of task order and type were not significant for Experts, while congruence detection improved the glossiness judgment of Novices and reduced that of Trainees. However, congruence detection did not differ by task order or group. Thus, although sketch training did not affect visual discrimination in figural congruence and gloss, it influenced the relationship between glossiness and highlight–shading congruence.</p>

DOI： 10.14947/psychono.36.3

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s10043-016-0295-6

Web of Science

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Total pages：996p, 図版 [18] p  

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J-GLOBAL

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