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KIYOKAWA Hiroaki
Mathematics, Electronics and Informatics DivisionAssistant Professor
Department of Information and Computer Sciences

Researcher information

■ Degree
  • Ph.D. in Engineering, Yamagata University
■ Field Of Study
  • Informatics, Perceptual information processing
  • Informatics, Sensitivity (kansei) informatics
  • Humanities & social sciences, Cognitive sciences
  • Humanities & social sciences, Experimental psychology
■ Career
  • Apr. 2023 - Present, Saitama University
  • Dec. 2021 - Mar. 2023, National Institute of Advanced Industrial Science and Technology
  • Apr. 2021 - Dec. 2021, Tokyo Institute of Technology
■ Educational Background
  • Apr. 2017 - Mar. 2021, Yamagata University
  • Apr. 2020 - Oct. 2020, University of New South Wales
  • Apr. 2016 - Mar. 2017, Yamagata University, Graduate School of Science and Engineering
  • Apr. 2012 - Mar. 2016, Yamagata University, Faculty of Engineering
■ Member History
  • Apr. 2025 - Present
    Society
  • Apr. 2022 - Present
■ Award
  • Dec. 2024, Human Communication Award, The Institute of Electronics, Information and Communication Engineers
    Keigo Yoshida;Hiroaki Kiyokawa;Ichiro Kuriki
    45532598
  • Jan. 2024, ベストプレゼンテーション賞(共同指導学生の受賞)
  • Nov. 2021, 優秀発表奨励賞
  • Mar. 2019, 最優秀QE発表賞
  • Jan. 2018, 2018年冬季大会ベストプレゼンテーション賞

Performance information

■ Paper
  • 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]
    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]
    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]
    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]
    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
■ MISC
  • 映像情報×認知科学(第2回)質感の視知覚               
    清川宏暁
    Volume:79, Number:3, First page:277, Last page:279, May 2025, [Reviewed], [Invited]
  • 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
  • 画像の不自然さを決定する彩度限界に関する研究               
    木村 滉輔; 清川 宏暁; 栗木 一郎
    Volume:36, Number:2, First page:72, Last page:76, Apr. 2024, [Reviewed]
    DOI:https://doi.org/10.24636/vision.36.2_72
    DOI ID:10.24636/vision.36.2_72
  • Towards a Psychophysically Plausible Simulation of Translucent Appearance
    Takehiro Nagai; Hiroaki Kiyokawa; Stephen Palmisano; Juno Kim
    SIGGRAPH Asia 2023 Posters, First page:1, Last page:3, 28 Nov. 2023, [Reviewed]
    ACM, English
    DOI:https://doi.org/10.1145/3610542.3626145
    DOI ID:10.1145/3610542.3626145
  • The Perception of Materials
    Hiroaki Kiyokawa
    The Journal of The Institute of Image Information and Television Engineers, Volume:76, Number:4, First page:483, Last page:484, 2022, [Reviewed], [Invited]
    Institute of Image Information and Television Engineers
    DOI:https://doi.org/10.3169/itej.76.483
    DOI ID:10.3169/itej.76.483, ISSN:1342-6907, eISSN:1881-6908
  • 照明条件による光沢感恒常性の成立と不成立の原因となる画像手掛かりの解明               
    清川宏暁; 南場拓斗; 長嶋陸; 寺嶋優太; 田代知範; 山内泰樹
    Volume:53, Sep. 2020, [Reviewed], [Lead]
  • 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
■ Lectures, oral presentations, etc.
  • 彩度限界の知覚と色統計に関するDNNを用いた研究               
    水野美和; 清川宏暁; 栗木一郎
    Jan. 2025
  • 明度の異なる青/緑の色刺激に対するオドボール効果とERPの相関               
    寺嶋遵仁; 清川宏暁; 栗木一郎
    Jan. 2025
  • 半透明感に対する形状認識のトップダウン効果               
    永井岳大; 清川宏暁; Juno Kim
    Jan. 2025
  • 形状と光沢感の相互作用に関する研究               
    高瀨翔己; 清川宏暁; 栗木一郎
    Sep. 2024
  • 彩度知覚と明るさ知覚の色相依存性と,彩度の時空間周波数による差異               
    梅田直翔; 福嶋さくら; 清川宏暁; 栗木 一郎
    Jan. 2024
  • 画像の不自然さを決定する彩度限界に関する研究               
    木村滉輔; 清川宏暁; 栗木一郎
    Jan. 2024
  • 質感の要素知覚メカニズムの独立性の検討               
    吉田圭吾; 清川宏暁; 栗木一郎
    Dec. 2023
  • 顔表情の画像特徴に基づく感情表現と言語に基づく感情表現の比較               
    清川宏暁; 中村大樹; 林隆介
    Jan. 2023
  • 半透明感を生起させる画像情報の解明 —光沢成分と陰影成分を用いたモデル化—               
    清川宏暁; 山内泰樹; 永井岳大; Juno Kim
    Nov. 2021
  • 光沢と陰影の3次元形状の違いから生まれる半透明感 -2次元画像情報を用いたモデル化-               
    清川宏暁; 山内泰樹; 永井岳大; Juno Kim
    Jan. 2021
  • サブバンドコントラスト強調による光沢感の上昇 -暗い光沢物体画像での特異な空間周波数特性-               
    清川宏暁; 田代知範; 山内泰樹; 永井岳大
    Sep. 2020
  • 輝度エッジ強調による光沢感操作が有効となる物理的・画像的条件               
    清川宏暁; 田代知範; 山内泰樹; 永井岳大
    Jan. 2020
  • 質感知覚における課題依存的な知覚学習               
    永井岳大; 小松柊斗; 清川宏暁; 田代知範; 山内泰樹
    Dec. 2018
  • 光沢感知覚における鏡面ハイライト以外の画像手掛かり ―映り込みの明瞭さと輝度エッジの関係―               
    清川宏暁; 田代知範; 山内泰樹; 永井岳大
    Jan. 2018
  • 低輝度領域に起因する光沢感 ―周辺環境の映り込みの効果―               
    清川宏暁; 川島祐貴; 山内泰樹; 永井岳大
    Jan. 2017
  • 透明感と光沢感の弁別に対する知覚学習効果               
    清川宏暁; 川島祐貴; 山内泰樹; 永井岳大
    Jan. 2016
■ Research projects
  • 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
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