{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,28]],"date-time":"2026-05-28T02:27:08Z","timestamp":1779935228894,"version":"3.53.1"},"reference-count":42,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2020,11,23]],"date-time":"2020-11-23T00:00:00Z","timestamp":1606089600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","award":["MOP 53301"],"award-info":[{"award-number":["MOP 53301"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["European Journal of Pain"],"published-print":{"date-parts":[[2021,3]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>Facial activity during pain is composed of varying combinations of a few elementary facial responses (so\u2010called Action Units). A previous study of experimental pain showed that these varying combinations can be clustered into distinct facial activity patterns of pain. In the present study, we examined whether comparable facial activity patterns can also be identified among people suffering from clinical pain; namely, shoulder pain.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Facial expressions of patients suffering from shoulder pain (<jats:italic>N<\/jats:italic>\u00a0=\u00a0126) were recorded while twice undergoing a battery of passive range\u2010of\u2010motion tests to their affected limbs (UNBC\u2010McMaster Shoulder Pain Expression Archive Database), which elicited peaks of acute pain. Facial expressions were analysed using the Facial Action Coding System to extract facial Action Units (AUs). Hierarchical cluster analyses were used to look for characteristic combinations of these AUs.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Cluster analyses revealed four distinct activity patterns during painful movements. Each cluster was composed of different combinations of pain\u2010indicative AUs, with one AU common to all clusters, namely, \u201cnarrowed eyes\u201d. Besides these four clusters, there was a \u201cstoic\u201d pattern, characterized by no discernible facial action. The identified clusters were relatively stable across time and comparable to the facial activity patterns found previously for experimental heat pain.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>These findings corroborate the hypothesis that facial expressions of acute pain are not uniform. Instead, they are composed of different combinations of pain\u2010indicative facial responses, with one omnipresent response, namely, \u201cnarrowed eyes\u201d. Raising awareness about these inter\u2010individually different \u201cfaces of pain\u201d could improve the recognition and, thereby, its diagnostic training for professionals, like nurses and physicians.<\/jats:p><\/jats:sec><jats:sec><jats:title>Significance<\/jats:title><jats:p>Similar to experimental pain, facial activity during evoked pain episodes in shoulder pain patients could be clustered into distinct faces of pain. Each cluster was composed of different combinations of single facial responses, namely: narrowed eyes, which is displayed either alone or in combination with opened mouth or wrinkled nose, or furrowed brows and closed eyes. These distinct faces of pain may inform the training of professionals and computers how to best recognize pain based on facial expressions.<\/jats:p><\/jats:sec>","DOI":"10.1002\/ejp.1691","type":"journal-article","created":{"date-parts":[[2020,11,2]],"date-time":"2020-11-02T06:50:59Z","timestamp":1604299859000},"page":"529-540","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":22,"title":["Faces of clinical pain: Inter\u2010individual facial activity patterns in shoulder pain patients"],"prefix":"10.1002","volume":"25","author":[{"given":"Miriam","family":"Kunz","sequence":"first","affiliation":[{"name":"Physiological Psychology Otto\u2010Friedrich University Bamberg Germany"},{"name":"Medical Psychology and Sociology University of Augsburg Augsburg Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kenneth","family":"Prkachin","sequence":"additional","affiliation":[{"name":"Department of Psychology University of Northern British Columbia British Columbia Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Patricia E.","family":"Solomon","sequence":"additional","affiliation":[{"name":"School of Rehabilitation Science McMaster University Hamilton Ontario Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stefan","family":"Lautenbacher","sequence":"additional","affiliation":[{"name":"Physiological Psychology Otto\u2010Friedrich University Bamberg Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2020,11,23]]},"reference":[{"key":"e_1_2_9_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/S1836-9553(10)70061-8"},{"key":"e_1_2_9_3_1","doi-asserted-by":"publisher","DOI":"10.1002\/art.23318"},{"key":"e_1_2_9_4_1","unstructured":"Asgarian A. Zhao S. Ashraf A. B. Browne M. E. Prkachin K. M. Mihailidis A. &Taati B.(2019).Limitations and Biases in Facial Landmark Detection\u2013An Empirical Study on Older Adults with Dementia. CVPR Workshops pp.28\u201336. arXiv:1905.07446."},{"key":"e_1_2_9_5_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.imavis.2009.05.007"},{"key":"e_1_2_9_6_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jpain.2019.01.002"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1007\/978-1-4613-0893-5_14"},{"key":"e_1_2_9_8_1","doi-asserted-by":"publisher","DOI":"10.1136\/ard.2003.007724"},{"key":"e_1_2_9_9_1","first-page":"117","volume-title":"Handbook of pain assessment","author":"Craig K. D.","year":"2011"},{"key":"e_1_2_9_10_1","volume-title":"Facial Action Coding System","author":"Ekman P. E.","year":"1987"},{"key":"e_1_2_9_11_1","first-page":"147","volume-title":"Reading and Understanding More Multivariate Statistics","author":"Hair J. 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