Performance information

• Top-down effects on translucency perception in relation to shape cues　　　　　　　　　　　　　　　
  Takehiro Nagai; Hiroaki Kiyokawa; Juno Kim
  PLOS ONE, Volume：20, Number：2, Feb. 2025, [Reviewed]
  It is well established that object shape perception significantly influences the perception of translucency. However, how object shape cues such as motion and binocular disparity affect the perception of translucency in rich environments, like virtual reality or real visual environments, remains unclear. This study aims to psychophysically measure the extent to which multiple object shape cues influence the perception of translucency. Additionally, we examined whether top-down factors, such as changes in cognitive attitude caused by the sequence of experiments, affect translucency perception. The results revealed that while motion and binocular disparity enhance translucency perception, this effect is confined to situations where shape cues are poor. Moreover, the effect became particularly pronounced when the experiments began with weak specular reflection stimuli, followed by the experiments using stimuli with specular reflection. In the case of translucent objects without specular reflection, strong shape information cannot be derived solely from shading patterns. These findings thus suggest that top-down factors related to shape modulate the influence of shape cues on translucency perception.
  PUBLIC LIBRARY SCIENCE, English, Scientific journal
  DOI：https://doi.org/10.1371/journal.pone.0314439
  DOI ID：10.1371/journal.pone.0314439, ISSN：1932-6203, Web of Science ID：WOS:001425429000021
• Commonalities and variations in emotion representation across modalities and brain regions.　　　　　　　　　　　　　　　
  Hiroaki Kiyokawa; Ryusuke Hayashi
  Scientific reports, Volume：14, Number：1, First page：20992, Last page：20992, Sep. 2024, [Reviewed], [Lead], ［International magazine］
  Humans express emotions through various modalities such as facial expressions and natural language. However, the relationships between emotions expressed through different modalities and their correlations with neural activities remain uncertain. Here, we aimed to unveil some of these uncertainties by investigating the similarity of emotion representations across modalities and brain regions. First, we represented various emotion categories as multi-dimensional vectors derived from visual (face), linguistic, and visio-linguistic data, and used representational similarity analysis to compare these modalities. Second, we examined the linear transferability of emotion representation from other modalities to the visual modality. Third, we compared the representational structure derived in the first step with those from brain activities across 360 regions. Our findings revealed that emotion representations share commonalities across modalities with modality-type dependent variations, and they can be linearly mapped from other modalities to the visual modality. Additionally, emotion representations in uni-modalities showed relatively higher similarity with specific brain regions, while multi-modal emotion representation was most similar to representations across the entire brain region. These findings suggest that emotional experiences are represented differently across various brain regions with varying degrees of similarity to different modality types, and that they may be multi-modally conveyable in visual and linguistic domains.
  English, Scientific journal
  DOI：https://doi.org/10.1038/s41598-024-71690-y
  DOI ID：10.1038/s41598-024-71690-y, PubMed ID：39251743, PubMed Central ID：PMC11385795
• The perception of translucency from surface gloss.　　　　　　　　　　　　　　　
  Hiroaki Kiyokawa; Takehiro Nagai; Yasuki Yamauchi; Juno Kim
  Vision research, Volume：205, First page：108140, Last page：108140, Apr. 2023, [Reviewed], [Lead], ［International magazine］
  Translucent objects (like fruit and wax) reflect and transmit incident light to generate complex retinal image structure. Understanding how we visually perceive translucency from these images is challenging, but previous studies have demonstrated that perceived shape and shading is important for perceiving translucency. We considered the possibility that perceived translucency might also depend on 3D shape inferred from surface gloss (i.e., shape from specular highlights). Here, we performed experiments to test whether interactions between specular and non-specular image properties generated by different 3D shape information influences perceived translucency. Results revealed that perceived translucency could be explained by incongruence in 3D shape used to generate specular and non-specular image components. We proposed a new computational model based on measurable image features informative of shading relative to specular highlights that accounted for 59% of the variability in judgments of perceived translucency from the result of 10-fold cross validation. This model was found to outperform other models based on explicit subjective measures of perceived surface shape, suggesting it implicitly taps much of the relevant geometric information necessary for predicting observer judgments of translucency for glossy materials. These results provide new insight into how the visual system might infer translucency from the structure of specular and non-specular shading generated by glossy semi-opaque materials.
  PERGAMON-ELSEVIER SCIENCE LTD, English, Scientific journal
  DOI：https://doi.org/10.1016/j.visres.2022.108140
  DOI ID：10.1016/j.visres.2022.108140, ISSN：0042-6989, eISSN：1878-5646, PubMed ID：36336645, Web of Science ID：WOS:000954904300001
• Effects of specular roughness on the perception of color and opacity.　　　　　　　　　　　　　　　
  Yuyang Cai; Hiroaki Kiyokawa; Takehiro Nagai; Leyla Haghzare; Matthew Arnison; Juno Kim
  Journal of the Optical Society of America. A, Optics, image science, and vision, Volume：40, Number：3, First page：A220-A229, Mar. 2023, [Reviewed], ［International magazine］
  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.
  English, Scientific journal
  DOI：https://doi.org/10.1364/JOSAA.479972
  DOI ID：10.1364/JOSAA.479972, PubMed ID：37133045
• Spatial Frequency Effective for Increasing Perceived Glossiness by Contrast Enhancement.　　　　　　　　　　　　　　　
  Hiroaki Kiyokawa; Tomonori Tashiro; Yasuki Yamauchi; Takehiro Nagai
  Frontiers in psychology, Volume：12, First page：625135, Last page：625135, Feb. 2021, [Reviewed], [Lead], ［International magazine］
  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.
  FRONTIERS MEDIA SA, English, Scientific journal
  DOI：https://doi.org/10.3389/fpsyg.2021.625135
  DOI ID：10.3389/fpsyg.2021.625135, ISSN：1664-1078, PubMed ID：33613400, PubMed Central ID：PMC7892470, Web of Science ID：WOS:000619274000001
• Luminance edge is a cue for glossiness perception based on low-luminance specular components　　　　　　　　　　　　　　　
  Hiroaki Kiyokawa; Tomonori Tashiro; Yasuki Yamauchi; Takehiro Nagai
  JOURNAL OF VISION, Volume：19, Number：12, Oct. 2019, [Reviewed], [Lead]
  The visual system is considered to employ various image cues from an object image to perceive its glossiness. It has been reported that, surprisingly, even for object images without specular highlights we can perceive glossiness by relying on low-luminance specular components (Kim, Marlow, & Anderson, 2012). This type of perceptual glossiness is referred to as dark gloss. However, it is still unclear whether dark gloss is observed commonly across various objects, and what image features are cues for dark gloss. To address these issues, we performed several psychophysical experiments. First, we measured perceived glossiness for a number of computer-graphics object images with natural specular reflection components (Full condition) and for those without high-luminance components of specular reflections (Dark condition). The results showed that dark gloss (glossiness perception in the Dark condition) was generally observed on almost all object images, while its intensity was rather different across the images. Then we psychologically or computationally measured several image features for the stimulus images, such as luminance edge number, recognizability of reflection images, and some highlight-related features, to examine their relations to perceived glossiness with a multiple regression analysis. The results demonstrated that luminance edge number was most strongly related to glossiness scores among the measured features only for object images with potent dark gloss. These results suggest that luminance edges are an effective cue for dark gloss under certain stimulus conditions.
  ASSOC RESEARCH VISION OPHTHALMOLOGY INC, English, Scientific journal
  DOI：https://doi.org/10.1167/19.12.5
  DOI ID：10.1167/19.12.5, ISSN：1534-7362, Web of Science ID：WOS:000492307500005
• Task-relevant Perceptual Learning for Judgments of Visual Material Features　　　　　　　　　　　　　　　
  KIYOKAWA Hiroaki; KAWASHIMA Yuki; YAMAUCHI Yasuki; NAGAI Takehiro
  Transactions of Japan Society of Kansei Engineering, Volume：17, Number：2, First page：309, Last page：319, Apr. 2018, [Reviewed], [Lead]
  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.
  Japan Society of Kansei Engineering, English
  DOI：https://doi.org/10.5057/jjske.tjske-d-18-00019
  DOI ID：10.5057/jjske.tjske-d-18-00019, eISSN：1884-5258, CiNii Articles ID：130006728097

• Skewness adaptation induced an asymmetric effect in glossiness perception but not in translucency.　　　　　　　　　　　　　　　
  Hiroaki Kiyokawa; Keigo Yoshida; Ichiro Kuriki
  Journal of Vision, Volume：24, First page：526, Last page：526, Oct. 2024, [Reviewed]
  English
• Manipulation of glossiness perception by contrast enhancement of high spatial frequency components　　　　　　　　　　　　　　　
  Hiroaki Kiyokawa; Tomonori Tashiro; Yasuki Yamauchi; Takehiro Nagai
  Journal of Vision, Volume：20, First page：364, Last page：364, Jun. 2020, [Reviewed]
  English
• Perceived Glossiness Based on Low-Luminance Specular Components Can Be Increased by Enhancing Luminance Edge Contrasts　　　　　　　　　　　　　　　
  Hiroaki Kiyokawa; Tomonori Tashiro; Yasuki Yamauchi; Takehiro Nagai
  I-PERCEPTION, Volume：10, First page：160, Last page：160, Sep. 2019, [Reviewed]
  English
• Image cues for glossiness perception obtained from low luminance specular reflection components.　　　　　　　　　　　　　　　
  Hiroaki Kiyokawa; Tomonori Tashiro; Yasuki Yamauchi; Takehiro Nagai
  Perception, Volume：48, First page：143, Last page：143, Aug. 2018, [Reviewed]
  English
• Glossiness perception not depending on specular highlights -impacts of luminance edges-　　　　　　　　　　　　　　　
  Hiroaki Kiyokawa, Tomonori Tashiro, Yasuki Yamauchi, Takehiro Nagai
  I-PERCEPTION, Volume：8, First page：48, Last page：49, Jul. 2017, [Reviewed]
  English

• Study on color representation in human cortex based on individual differences in perception and brain activity　　　　　　　　　　　　　　　
  JSPS, Grant-in-aid for Scientific Research, Class A, Apr. 2024 - Mar. 2028
  Ichiro Kuriki; Masami K Yamaguchi; So Kanazawa; Sae Kaneko; Takehiro Nagai; Jiale Yang; Kenichi Ueno; Hiroaki Kiyokawa, Saitama University
  Grant amount(Total)：47710000, Direct funding：36700000, Indirect funding：11010000
  Grant number：24H00702
• 視覚情報工学アプローチによる感性的質感知覚メカニズムの解明　　　　　　　　　　　　　　　
  01 Apr. 2023 - 31 Mar. 2026
  Grant amount(Total)：3380000, Direct funding：2600000, Indirect funding：780000
  Grant number：23K16985