Style, Sentiment, and Quality of Undergraduate Writing in the AI Era: A Cross-Sectional and Longitudinal Analysis of 4,820 Authentic Empirical Reports

Style, Sentiment, and Quality of Undergraduate Writing in the AI Era: A Cross-Sectional and Longitudinal Analysis of 4,820 Authentic Empirical Reports | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Style, Sentiment, and Quality of Undergraduate Writing in the AI Era: A Cross-Sectional and Longitudinal Analysis of 4,820 Authentic Empirical Reports Matthew HC Mak, Lukasz Walasek This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7465165/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract As generative artificial intelligence (GenAI) becomes widespread in education, its influence on students’ academic practice raises concern. We conducted pre-registered analyses of 4,820 empirical reports written by 2,000 psychology undergraduates (2016-2025). Following ChatGPT’s 2022 release, prevalence of ChatGPT-associated lexical markers (e.g., delve) surged until 2024, then declined in 2025, possibly due to students masking GenAI traces. Writing style (indexed by lexical diversity/density/sophistication, nominalisation, readability) became increasingly formal post-ChatGPT, diverging from predicted/historical trends. Consistent with GenAI’s positivity bias, sentiment also became more positive, independent of topic or result’s statistical significance, raising questions about its potential impact on students’ critical engagement. Despite the stylistic changes, writing quality (indexed by grades and feedback) showed no discernible shifts. Exploratory analysis asked GPT models to rewrite pre-ChatGPT reports, and these GPT-rewritten texts resembled post-ChatGPT reports more in style and sentiment. Finally, no students disclosed AI use despite clear guidelines, highlighting the ineffectiveness of voluntary disclosure. Social science/Psychology/Human behaviour Social science/Language and linguistics Artificial Intelligence (AI) Education Writing Style Sentiment Writing Quality Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7465165","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":506282733,"identity":"1fe55495-606c-4fa2-957d-9b76aaa7adaa","order_by":0,"name":"Matthew HC Mak","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/klEQVRIiWNgGAWjYJACZgjFxvgATAEhGEjg1sDYDNXCbECyFjaoIgJadNvPH39cUHEYyDiWVs1Tcy+xj/1YAsOPGobEmQ3YtZidSWZsnnHmMJCRduw2z7HixDaetAOMPccYEmfjsMXsAFALb9ttICO97XYOW0JumwR7AwNvA0PiPFxazj8GavkH1HL+eVtxzj+IFsa/+LTcANnSANRyI+0Yc24bSAvbAWaQLTgdduOx4WyeY/95zG48S5b+25dQD/RLwmGZYxLGOL1/PvHBZ56aNDmz82mGH2d8SzCWbz9m+PBNjY3sjAM4rIECHhTeAXwROQpGwSgYBaOAMAAASrdbvVEI7HkAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0001-7237-4931","institution":"University of Warwick","correspondingAuthor":true,"prefix":"","firstName":"Matthew","middleName":"HC","lastName":"Mak","suffix":""},{"id":506282734,"identity":"de23a8d3-9db8-4245-98f8-fb2c683fb88a","order_by":1,"name":"Lukasz Walasek","email":"","orcid":"","institution":"University of Warwick","correspondingAuthor":false,"prefix":"","firstName":"Lukasz","middleName":"","lastName":"Walasek","suffix":""}],"badges":[],"createdAt":"2025-08-26 17:15:29","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7465165/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7465165/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":90577121,"identity":"651b7fad-0a00-45db-8685-56bb55efcff0","added_by":"auto","created_at":"2025-09-04 09:27:32","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1580487,"visible":true,"origin":"","legend":"Article File","description":"","filename":"StyleSentimentandQualityofUndergraduateWritingintheAIEra.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7465165/v1_covered_50905265-2fd4-4ce3-a637-78d21c5f4cfc.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Style, Sentiment, and Quality of Undergraduate Writing in the AI Era: A Cross-Sectional and Longitudinal Analysis of 4,820 Authentic Empirical Reports","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Artificial Intelligence (AI), Education, Writing Style, Sentiment, Writing Quality","lastPublishedDoi":"10.21203/rs.3.rs-7465165/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7465165/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"As generative artificial intelligence (GenAI) becomes widespread in education, its influence on students’ academic practice raises concern. 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