{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:02:56Z","timestamp":1760148176397,"version":"build-2065373602"},"reference-count":26,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2023,4,10]],"date-time":"2023-04-10T00:00:00Z","timestamp":1681084800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["18H01059"],"award-info":[{"award-number":["18H01059"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Due to COVID-19, various lecture styles are being explored. On-demand lectures are attracting increasing attention due to advantages such as being able to watch without restrictions due to location and time. In contrast, on-demand lectures have disadvantages, such as no interaction with the lecturer, so the quality of on-demand lectures should be improved. Our previous study showed that when participants nod without showing their faces in a real-time remote lecture, their heart rate state changes to arousal and nodding can increase arousal. In this paper, we hypothesize that nodding during on-demand lectures increases participants\u2019 arousal levels, and we investigate the relationship between natural and forced nodding and the level of arousal based on heart rate information. Students taking on-demand lectures rarely nod naturally, so we used entrainment to encourage nodding by showing a video of another participant nodding, and by forcing the participants to nod when the other participant nodded in the video. The results showed that only participants who nodded spontaneously changed the value of pNN50, an index of the arousal level, which reflected a state of high arousal after one minute. Thus, participants\u2019 nodding in on-demand lectures can increase their arousal levels; however, the nodding must be spontaneous, not forced.<\/jats:p>","DOI":"10.3390\/s23083858","type":"journal-article","created":{"date-parts":[[2023,4,10]],"date-time":"2023-04-10T03:49:29Z","timestamp":1681098569000},"page":"3858","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Investigation of the Effect of Students\u2019 Nodding on Their Arousal Levels in On-Demand Lectures"],"prefix":"10.3390","volume":"23","author":[{"given":"Kotaro","family":"Sumida","sequence":"first","affiliation":[{"name":"Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada, Kobe 657-8501, Hyogo, Japan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3583-6118","authenticated-orcid":false,"given":"Ayumi","family":"Ohnishi","sequence":"additional","affiliation":[{"name":"Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada, Kobe 657-8501, Hyogo, Japan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2260-3788","authenticated-orcid":false,"given":"Tsutomu","family":"Terada","sequence":"additional","affiliation":[{"name":"Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada, Kobe 657-8501, Hyogo, Japan"}]},{"given":"Hiroshi","family":"Kato","sequence":"additional","affiliation":[{"name":"Faculty of Liberal Arts, The Open University of Japan, 2-12 Wakaba, Mihama, Chiba 251-8586, Chiba, Japan"}]},{"given":"Hideaki","family":"Kuzuoka","sequence":"additional","affiliation":[{"name":"Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo 113-0033, Tokyo, Japan"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-7959-2787","authenticated-orcid":false,"given":"Yoshihiko","family":"Kubota","sequence":"additional","affiliation":[{"name":"Graduate School of Education, Tamagawa University, 6-1-1 Tamagawagakuen, Machida 194-8610, Tokyo, Japan"}]},{"given":"Hideyuki","family":"Suzuki","sequence":"additional","affiliation":[{"name":"Faculty of Humanities and Social Sciences, Ibaraki University, 2-1-1 Bunkyo, Mito 310-0056, Ibaraki, Japan"}]},{"given":"Masahiko","family":"Tsukamoto","sequence":"additional","affiliation":[{"name":"Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada, Kobe 657-8501, Hyogo, Japan"}]}],"member":"1968","published-online":{"date-parts":[[2023,4,10]]},"reference":[{"key":"ref_1","unstructured":"(2023, January 30). 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