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HUMOR, ANOMALIES, AND LANGUAGE: A STUDY OF LINGUISTIC INTERACTION IN VIRAL TIKTOK ANOMALIES AND THEIR POTENTIAL IN CRITICAL EDUCATION

SYAPUTRI, Wuri

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„LINGUARUM UNIVERSE”, VOLUME 2, ISSUE 3 DOI:10.5281/zenodo.17481822 266 HUMOR, ANOMALIES, AND LANGUAGE: A STUDY OF LINGUISTIC INTERACTION IN VIRAL TIKTOK ANOMALIES AND THEIR POTENTIAL IN CRITICAL EDUCATION Wuri SYAPUTRI Universitas Andalas, Indonesia Email: [email protected]. ABSTRACT: This work analyzes the sociolinguistic critical media pedagogical implications of the TikTok phenomenon dubbed Italian Brainrot, focusing on its linguistic and semiotic TikTok strands. It aims to comprehend the interaction frameworks associated with language, humor, and digital culture, especially in the context of viral ‘anomalous’ characters on TikTok, alongside the implications for contemporary systems of communication and identity. The study applies qualitative description and discourse analysis of multiple texts to 15 anomaly characters from mediated portrayals. These characters, including Tung Tung Tung Sahur and Bombardiro Crocodillo, display notable features of nonstandard phonology, including rhyming, pseudo-Italian inflectional morphology, repetition, and symbolic sounds that comport with their viral and meme-like character. The outlined findings show how anomaly content functions as a form of playful digital linguistics, informed by algorithmic logic, remix culture, and postmodern aesthetics. From a socio-linguistic angle, this illustrates how Gen Alpha users repurpose participatory, often countercultural appropriation of language as a means to forge ingroup solidarity and navigate attention algorithms. KEYWORDS: Digital Humor, TikTok Anomalies, Sociolinguistics Introduction The emergence of social media has changed the ways people communicate, joke, or interact with language. TikTok, in particular, has been known for the quick spread of viral content that lacks any form of logic, coherence, or linguistic decorum (Greco & Leone, 2025; Palombo, 2024; Serazio, 2023). In particular, a certain class of TikTok Videos denominated as ‘anomalies’ has become a viral sensation. These short videos of cacophonic sounds, juxtaposed with bizarre visuals, repetitive phrases, and nonsensical humor, can be termed the audio-visual tapestry of contemporary Indonesia. Although these videos may seem like chaotic noise to the untrained eye, there is a richly complex tapestry of unique linguistic and cultural dimensions buried under the surface. My focus will be on fifteen such cases of anomalies as discussed in the Kompas Tekno article of April 2025, “Daftar Nama Anomali TikTok yang Lagi Viral: Ada Tung Tung Tung Sahur.” The content of these videos is captioned as “Tung Tung Tung Sahur,” “Si Nopal Nangis,” among others. The corpus that these clips constitute is invaluable for the study of linguistic creativity in social discourse and the norms of communication in contemporary society. To interpret the above oddities, this study relies on multiple interrelated theoretical frameworks. To begin with, sociolinguists consider the scholarship of Hymes (2020) and Wardhaugh & Fuller (2021) regarding the disruption and variation of languages within certain speech communities. Such TikTok anomalies provide evidence of how virtual communities formulate their own semiotic norms, often defying conventional standards of coherence, syntax, and pragmatic meaning. From this perspective, these anomalies should not be regarded as communication breakdowns, but rather alternative expressions of social significance within a particular context. As a second point, the study incorporates humor theory, especially stated by et al. (2024), Bellieni (2023), and Straßburger (2022), the incongruity theory, which states that laughter comes from a clash between expectation and reality. These TikTok anomalies include abrupt shifts, nonsensical repetition, and audio that is purposely out of sync. All of these fit the definition of humor produced by cognitive dissonance. Moreover, the concept of the carnival or carnivalesque as developed by Bakhtin (t.t.) provides a useful lens for considering these videos as digital carnival, places where social order is momentarily turned upside down, authority ridiculed, and disorder embraced as release and defiance. Finally, the research draws from Holmes & Corbett (2022)’s theory of critical pedagogy. Holmes & Corbett underscore the need to use cultural texts—regardless of how unconventional they are—as a vehicle to ignite dialogue and awareness. This study argues that TikTok anomalies can be access points for deeper educational contemplation. Because of their ephemeral popularity, they can be effectively „LINGUARUM UNIVERSE”, VOLUME 2, ISSUE 3 DOI:10.5281/zenodo.17481822 267 harnessed in classrooms that aim to integrate critical literacy with contemporary media. Through the analysis of the functions of these anomalies and their messages about society, power, identity, and media construction, educators could engage students in debates about cultural value systems and neologisms. Although past studies on TikTok and digital humor (Hennefeld, 2022; Neilan, 2023; Picado, 2022) have primarily centered on more conventional narrative or comedic forms, there is a lack of research on the so-called “brainrot” style content. Much of the existing scholarship either considers this type of content meaningless or overlooks its underlying linguistic and cultural frameworks. This study aims to treat these anomalies as purposeful communication and, therefore, deserving of closer examination. Furthermore, there is a striking absence of research connecting these chaotic linguistic constructs to the aims of critical education, especially in the Indonesian context. This study integrates sociolinguistic analysis with humor theory and pedagogical application, arguing that such content, often perceived as nonsensical, reveals intricate patterns of learner interaction and functions as an instrument of critical pedagogy. Research Methodology This study utilizes a qualitative descriptive approach (Litosseliti, 2024) to examine the linguistic, semiotic, and sociocultural aspects of anomalies on TikTok that go viral within the Indonesian digital landscape. The core TikTok anomalies are 15 viral anomalies TikTok which are mentioned in the article of Kompas Tekno dated April 24, 2025, “Daftar Nama Anomali TikTok yang Lagi Viral: Ada Tung Tung Tung Sahur” source: https://tekno.kompas.com/read/2025/04/24/12350027/daftar-nama-anomalitiktok-yang-lagi-viral-ada-tung-tung-tung-sahur?page=2. These anomalies were selected based on their popularity, collective recognition, and the presence of salient auditory or linguistic features that violate standard speech communication. Instead of treating the videos as separate texts, the study considers them as cultural texts resulting from digital interplay, humor, and multimodal imaginative acts. The data gathering processes are a combination of documentation and observation (Chalmers & Cowdell, 2021; Taherdoost, 2021, 2022). Each anomaly was linked to its best-known or original video version, and in relevant cases, the audio-visual material was transcribed. Important components were captured, including complex sound patterns, relevant visuals, repetitive elements, language, and audience interaction (commenting and remixing). Contextual metadata, such as video captions, hashtags, and interaction metrics, were also noted to capture the communicative context within which each of the anomalies circulated. For the analysis, the study utilizes multimodal discourse analysis (Kress & van Leeuwen, 2001) to explore the interplay of language, sound, images, and digital interactions as they create meaning. This perspective permits access to the social order and culture in ways that may seem disorganized or illogical, and yet complex. Features of language are approached from sociolinguistics with a focus on deviation, repetition, informal syntax, and emergent slang. Humorous components are analyzed via incongruity theory and the carnivalesque to reveal the intersection of absurdity and humor in digital contexts. In the pursuit of critical education, the findings are situated within Freirean pedagogy. The study specifically focuses on phenomena that warrant inquiry as they could function within the framework of media literacy or reflectivity in education. This analysis is hypothetical, although it rests on frameworks of critical literacy, especially those that seek to dismantle popular media for the purpose of enabling learners to challenge and reconstruct dominant narratives with constructive critical consciousness. The study's reliability is achieved through triangulation, which entails integrating several theories into a single analysis, in this case, linguistics, humor, and pedagogy, and employing publicly available and verifiable evidence. Research Result This research is grounded on qualitative descriptive methods and multimodal discourse analysis conducted on 15 TikTok anomalies as outlined in the Kompas Tekno article dated April 2025. This study reveals some of the salient patterns pertaining to the linguistic and semiotic construction of this particular genre. The anomalies here are not merely treated as humorous or nonsensical figures, but rather as purposeful manifestations of digital language play that function under particular cultural and media logics. From the perspective of multimodal analysis, it is clear that every anomaly incorporates sound, images, and language to generate meaning via contrast, excess, and absurdity. In the visual dimension, the characters merge animal features with machines, food, or household items, resulting in hybrid surreal forms. From the linguistic perspective, such names often exhibit phonetic patterns like rhyme, repetition, reduplication, or invented Italian-sounding suffixes such as –ini, -ino, and -ina, „LINGUARUM UNIVERSE”, VOLUME 2, ISSUE 3 DOI:10.5281/zenodo.17481822 268 adding a playful and exotic flavor to the content. These patterns align with the incongruity theory of humor, where an audience is presented with and delights in the unexpected. In the context of sociolinguistics, such names serve as a deviation from the usual conventions of naming. Their purpose is not to identify or describe in a conventional way, but rather to evoke a perverse form of amusement and sound-induced disorientation. The analysis also reveals that many of these names and sounds are processed through AI-generated voices in Italian or Indonesian, which shows how language is technologically mediated and adds yet another strangeness. For instance, Tung Tung Tung Sahur incorporates local Indonesian culture and onomatopoeic words, whereas Tralalero Tralala and Bombardiro Crocodillo are based on rhythmic Italian phonetics. The narratives of each character are often sparse and conveyed in a flat or melodramatic, exaggerated style, which humorously contrasts the absurd design of the character and the serious narration. These features are vital to the genre’s brainrot style—content that shatters coherence, logic, and linearity in favor of chaotic entertainment. The combination of algorithmic nonsense and meme logic is what fuels engagement and virality within TikTok’s participatory ecosystem. The table below presents the multimodal and linguistic characteristics of the 15 TikTok anomalies analyzed. Picture 1. TikTok Anomaly Pictures (Data and picture source: Hardiyansyah (2025)) ‘ Table 1: TikTok Anomaly Analysis Based on Multimodal and Linguistic Features No . Anomaly Name Visual Hybrid Description Language/Voic e Used Linguistic Features & Multimodal Markers 1 Bombardir o Crocodillo Crocodile + fighter jet AI voice (Italian) Consonant repetition, suffix - illo, hybrid metaphor 2 Tralalero Tralala Shark + human shoes AI voice (Italian) Rhythmic reduplication, sound mimicry 3 Tung Tung Tung Sahur Wooden kentongan + human traits AI voice (Indonesian) Onomatopoei a, religious/cultural reference „LINGUARUM UNIVERSE”, VOLUME 2, ISSUE 3 DOI:10.5281/zenodo.17481822 269 4 Ballerina Cappucina Ballerina + coffee cup AI voice (Italian) Feminized suffix -ina, soft phonetics 5 Brr Brr Patapim Unknown machine + abstract form Non-verbal (sound only) Sound effects, consonant rhythm 6 Boneca Ambalabu Doll + undefined pattern Mixed (ItalianPort.) Invented vocabulary, soft consonant blend 7 Bombombi ni Gusini Bomb-like twins + face AI voice (Italian) Rhyming -ini suffixes, mirroring 8 Zucchini Macanini Zucchini + tiger AI voice (Italian) Food-animal pun, lexical parody 9 Trulimero Trulicina Unclear creature duo AI voice (Italian) Name symmetry, reduplication 10 Cappucino Assasino Coffee cup + assassin body AI voice (Italian) Semantic contrast (soft vs. violent) 11 Pussini Sussini Cat + abstract/soft imagery AI voice (Italian) Sibilance, rhymed suffix -ini 12 Bluberini Octopusini Octopus + soft cartoon face AI voice (Italian) Rhyming + aquatic symbolism 13 Lirili Larila Fairy/music al type figure Musical voice overlay Phonetic melody, sound play 14 Pot Hotspot Wi-Fi pot hybrid AI voice (English mix) Techlanguage pun, metaphorical use 15 Chimpanzi ni Bananini Monkey + banana hybrid AI voice (Italian) Food-animal pun, childlike sound The various modes of communication enhance the understanding of these videos as social practices. Following the proposed method, the anomalies are not treated as incoherent chaos; instead, they are framed as cultural and linguistic performances within a digital logic system. The collective amusement and identity play provided by TikTok users is made possible through the bizarre visuals, AI voice-over, remixable format, and the heavy insistence on repetition. If we consider Freirean critical pedagogy, these anomalies become an invitation for dialogue and contemplation. They can be taught as unconventional yet relatable materials and prompts for analyzing the mediation of language and culture through algorithms, artificial voices, and viral formats. The nonsensical nature of the anomalies conceals a deeper layer as creative expression that engages urgent questions of digital literacy, meme politics, humor across generations, and more. Discussion The current analysis shows that the anomalies of TikTok, which combine AI-generated narration, visual surrealism, and playful fracturing of language, exemplify participatory parody and creative digital language use. This study follows (Hrazdil, 2024) observations that “brainrot slang reflects the generation's humor, values, and experiences” and functions as a unique cultural shorthand amongst adolescents. Our in-depth study of -ini suffixes, rhyme, and onomatopoeic naming identifies generational in-group coding and supports their argument regarding the anomalies' application as generational in-group codes. The pedagogical aspect of the study aligns with prior work, indicating that humor, when applied appropriately, increases comprehension of content and engagement within short videos. Ning dkk. (2022); Xiao & Yu (2022 2022) observed that humor acts as an amplifier for engagement online, albeit only under lower severity conditions. This supports our conclusion that, due to being playful and risk-free, anomalies can enhance media literacy and stimulate critical thinking „LINGUARUM UNIVERSE”, VOLUME 2, ISSUE 3 DOI:10.5281/zenodo.17481822 270 among students, provided they are presented within the right parameters. Moreover, the investigation adds to the body of literature that has examined meme-based pedagogy and multimodal communication, which focuses on the pedagogical potential of user-generated content in teaching digital literacy (Becker et al.). Nevertheless, this study highlights the gaps that other scholars have identified. Concerns regarding cognitive overload due to fast-paced media exposure, referred to as “TikTok brainrot,” through a neuroscientific lens, do hold some validity. The consumption of short videos on platforms such as TikTok is associated with reduced structural volume of the brain and an increase in the rate of attention deficit (Bulut, 2023; Kohler, 2023; Ye et al., 2025). This raises noteworthy concerns about the cognitive pedagogical costs incurred when the teaching of cognitive anomalies is done without pedagogical boundaries or scaffolded frameworks. Ultimately, while the study focuses on cultural inclusion and resistance, Ebner (2023) and Martino (2023) highlight the presence of insidious racial and alt-right stereotypes concealed within humor. The sampled deviations from the norm in this study may seem whimsical and apolitical, yet future research must be alert to attempts by extremist movements to co-opt such content, especially in light of the remix culture where algorithms intertwine innocuous material with harmful ideologies. Conclusion This study has explored the linguistic and semiotic dimensions of TikTok anomaly content—also known as Italian Brainrot—by examining 15 popular character memes sourced from mass media. Through a qualitative descriptive method and multimodal discourse analysis, the study found that these anomalies are not merely humorous or absurd content, but complex linguistic performances that embody contemporary digital culture. Their naming conventions, visual hybridity, and AI-generated narration reflect a postmodern aesthetics of fragmentation, irony, and playful incoherence. Linguistically, they challenge normative structures through creative sound patterns, onomatopoeia, and pseudo-Italian phonetics, which serve as both in-group digital codes and vehicles of affective engagement. From a sociolinguistic and critical pedagogical lens, TikTok anomalies offer potential value as learning materials. They resonate with youth culture and digital media practices, making them accessible entry points for media literacy, language play, and critical reflection on algorithmic culture. However, this potential must be weighed against existing concerns—ranging from cognitive overload to emotional risks and the possibility of misappropriation in harmful online subcultures. Overall, the study contributes to the growing body of research on internet linguistics, multimodal discourse, and educational media. It underscores the importance of recognizing non-traditional linguistic texts as culturally significant and worthy of academic and pedagogical attention. Future research may expand by incorporating audience reception studies and examining algorithmic dynamics. REFERENCES: Attardo, S., Chłopicki, W., & Forabosco, G. (2024). The Role of Incongruity in Humorous Texts. Dalam T. E. Ford, W. Chłopicki, & G. Kuipers (Ed.), De Gruyter Handbook of Humor Studies (hlm. 105–124). De Gruyter. https://doi.org/10.1515/9783110755770-007 Bakhtin, M. M. (t.t.). The dialogic imagination: Four essays. Diambil 11 Juni 2025, dari https://books.google.com/books?hl=id&lr=&id=cblaBAAAQBAJ&oi=fnd&pg=PT 8&dq=Mikhail+Bakhtin+&ots=5KoUaxozwt&sig=rCVZrZG1WoKbqvd1z6O2b_0 xABQ Becker, D., Kersten, S., Ludwig, C., Schildhauer, P., & Stadler-Heer, S. (2024). Born-Digital Text in English Language Teaching: The State of Play. Dalam S. Kersten & C. Ludwig (Ed.), //Born-Digital Texts in the English Language Classroom (hlm. 1–29). Multilingual Matters. https://doi.org/10.21832/9781800414815-002 Bellieni, C. V. (2023). Laughter: A signal of ceased alarm toward a perceived incongruity between life and stiffness. //New Ideas in Psychology, 68, 100977. https://doi.org/10.1016/j.newideapsych.2022.100977 „LINGUARUM UNIVERSE”, VOLUME 2, ISSUE 3 DOI:10.5281/zenodo.17481822 271 Bulut, D. (2023). The association between attention impairments and the internet and social media usage among adolescents and young adults with potential consequences: A review of the literature. //Psychology, 14(8), 1310–1321. https://doi.org/10.4236/psych.2023.148073 Chalmers, J., & Cowdell, F. (2021). What are quantitative and qualitative research methods? A brief introduction. //Dermatological nursing, 20(2). https://search.ebscohost.com/login.aspx?direct=true&profile=ehost&scope=site&a uthtype=crawler&jrnl=14773368&AN=151243679&h=ooepa4n2eivIcHdStP%2B XsfjRvk5TtsF%2Fp4OMYAi3Y3l4XMHT7jzl6i3w9JJM2tFCuV%2F4QnTWdEd UUFgADBeVNA%3D%3D&crl=c\ Đorđević, J. (2022). Digital media discourse in linguistic research. – In: Faculty of Philosophy in Niš. https://www.academia.edu/download/103156616/Jasmina_%C4%90or%C4%91evi c_Digital_media_discourse_in_linguistic_research.pdf Ebner, J. (2023). Going mainstream: How extremists are taking over. Bonnier Books UK. https://books.google.com/books?hl=id&lr=&id=GT29EAAAQBAJ&oi=fnd&pg= PT5&dq=the+presence+of+insidious+racial+and+altright+stereotypes+concealed+within+humor.+The+sampled+deviations+from+the +norm+in+this+study+may+seem+whimsical+and+apolitical&ots=_H34AzonHG &sig=-RBEV03GEDQI9QqZx_COcxEcIQ0 Greco, C., & Leone, M. (2025) Wearing the Veil in the Web: Transformations of Social Norms and Everyday Practices in the Digital Sphere Within the MENA Region. //International Journal for the Semiotics of Law - Revue Internationale de Sémiotique Juridique. https://doi.org/10.1007/s11196-025-10277-w Hardiyansyah, Z. (2025, April 24). Daftar Nama Anomali TikTok yang Lagi Viral, Ada Tung Tung Tung Sahur. https://tekno.kompas.com/read/2025/04/24/12350027/daftar-nama-anomali-tiktokyang-lagi-viral-ada-tung-tung-tung-sahur?page=all. Hennefeld, M. (2022). The problem of film comedy in the twenty-first century. //New Review of Film and Television Studies, 20(1), 101–118. https://doi.org/10.1080/17400309.2021.1968711 Holmes, P., & Corbett, J. (2022). Critical Intercultural Pedagogy for Difficult Times. Routledge. https://api.taylorfrancis.com/content/books/mono/download?identifierName=doi& identifierValue=10.4324/9781003150756&type=googlepdf Hrazdil, T. (2024). Linguistic devices of humor in popular memes. https://theses.cz/id/yv1w23/Hrazdil_thesis.pdf Hymes, D. (2020). The Scope of Sociolinguistics. International Journal of the Sociology of Language, 2020(263), 67–76. https://doi.org/10.1515/ijsl-2020-2084 Kohler, T. J. (2023). Caught In The Loop: The Effects of The Addictive Nature Of Short-form Videos On Users’ Perceived Attention Span And Mood [B.S. thesis, University of Twente]. http://essay.utwente.nl/96577/ Kress, G., & van Leeuwen, T. (2001). Reading and writing with images: A review of four texts. Reading Images: The Grammar of Visual Design. JAI. Litosseliti, L. (2024). Research methods in linguistics. Bloomsbury Publishing. https://books.google.com/books?hl=id&lr=&id=efQlEQAAQBAJ&oi=fnd&pg=PP 1&dq=qualitative+descriptive+approach+in+linguistics&ots=WJbsv1v4_h&sig=O kfMYTCsy91nIhAa06rssYWIFWs Martino, M. (2023). White Noise: Linguistic Appropriation, Corporate Advertising, and Social Media. McGill University (Canada). https://search.proquest.com/openview/fedffd5d9db5ac7c551dbdfe2d0d7ae6/1?pqorigsite=gscholar&cbl=18750&diss=y „LINGUARUM UNIVERSE”, VOLUME 2, ISSUE 3 DOI:10.5281/zenodo.17481822 272 Neilan, C. (2023). Moving away from the Monoplot: Conventional narrative structure in the screenplay and the unconventional alternatives [PhD Thesis, Manchester Metropolitan University]. https://e-space.mmu.ac.uk/id/eprint/632165 Ning, Y., Hu, C., Tu, T., & Li, D. (2022). Offensive or amusing? The study on the influence of brand-to-brand teasing on consumer engagement and behavioral intention based on social media. Frontiers in Psychology, 13, 966254. https://doi.org/10.3389/fpsyg.2022.966254 Palombo, N. G. (2024). " Sexual Context Collapse” on TikTok: Platform Politics, Content Moderation, and User Agency in Platform Governance. https://yorkspace.library.yorku.ca/items/a40bc454-cb6a-42d0-92eb-b94b37b8f926 Picado, B. (2022). The pace of a visual joke: Narrative rhythm in daily comic strips. Fictions: XXI, 2022, 89–105. Serazio, M. (2023). The Authenticity Industries: Keeping It" Real" in Media, Culture, and Politics. Stanford University Press. https://books.google.com/books?hl=id&lr=&id=ssrfEAAAQBAJ&oi=fnd&pg=PT 5&dq=TikTok,+in+particular,+has+been+known+for+the+quick+spread+of+viral+ content+which+lacks+any+form+logic,+coherence,+or+linguistic+decorum.+&ots =tjSpS088kx&sig=xA2TvzqcXvmHccBSikt24JNhKlc Straßburger, L. (2022). Humor and horror: Different emotions, similar linguistic processing strategies (Vol. 13). Walter de Gruyter GmbH & Co KG. https://books.google.com/books?hl=id&lr=&id=E_RjEAAAQBAJ&oi=fnd&pg=P P5&dq=especially+the+incongruity+theory,+which+states+that+laughter+comes+f rom+a+clash+between+expectation+and+reality&ots=F3Pp0upddq&sig=QfywwR taArfJxo1UdlnKxdOHU24 Taherdoost, H. (2021). Data collection methods and tools for research: a step-by-step guide to choosing data collection techniques for academic and business research projects. //International Journal of Academic Research in Management (IJARM), 10(1), 10–38. Taherdoost, H. (2022). What are the different research approaches? Comprehensive review of qualitative, quantitative, and mixed-method research, their applications, types, and limitations. Journal of Management Science & Engineering Research, 5(1), 53–63. https://doi.org/10.30564/jmser.v5i1.4538 Thomson, P. (2024). Doctoral memes as public pedagogy? Or, heaven knows I’m miserable now. Studies in Continuing Education, 1–19. https://doi.org/10.1080/0158037X.2024.2417095 Wardhaugh, R., & Fuller, J. M. (2021). An introduction to sociolinguistics. John Wiley & Sons. https://books.google.com/books?hl=id&lr=&id=y0orEAAAQBAJ&oi=fnd&pg=P R13&dq=Wardhaugh+%26+Fuller+&ots=MovyY8kHvm&sig=HE6jnK4BOp3lFS Yqu8jacdQYhsw Xiao, Y., & Yu, S. (2022). Using humor to promote social distancing on TikTok during the COVID-19 pandemic. //Frontiers in Psychology, 13, 887744. https://doi.org/10.3389/fpsyg.2022.887744 Ye, J.-H., Zheng, J., Nong, W., & Yang, X. (2025). Potential Effect of Short Video Usage Intensity on Short Video Addiction, Perceived Mood Enhancement ('TikTok Brain’), and Attention Control among Chinese Adolescents.// International Journal of Mental Health Promotion, 27(3). https://doi.org/10.32604/ijmhp.2025.059929 This is an open access article distributed under the CC BY-NC 4.0 license - http://creativecommons.org/licenses/by-nc/4.0