Professional communication content as a non-invasive indicator of situational stress under increased work-rest schedule intensity (using the model of cosmonauts' activity)

Abstract

Introduction. The reliability of a human operator’s performance in extreme and isolated working conditions naturally decreases as the intensity of the work–rest schedule increases. The authors consider the substantive analysis of professional speech to be a standard, non invasive method of remote assessment of functional state, which does not require additional equipment or the specialist’s working time.The study aims to establish a quantitative relationship between the degree and substantive type of workload intensity during the workday and the characteristics of the operator’s professional communication, as well as to assess the suitability of speech indicators for detecting acute situational stress.Materials and methods. The researchers analyzed the transcripts of negotiations between 14 cosmonauts from the Russian segment of the International Space Station and the Mission Control Center, accumulated during the "Content" space experiment (2015–2018): 1279 active days. For each day, using the expanded author’s version of the W&R intensity scale, a score of intensity (from 0 to 10) and a content type were assigned. The authors used quantitative content analysis of speech and non parametric statistical methods (Mann–Whitney U test, Spearman’s rank correlation, and Kruskal–Wallis test).Results. Three hundred and seventy days (28.9%) were classified as strenuous. On such days the overall communication volume doubled (from 11.2 to 22.6 statements per day; p<0.001). The speech signature was two-layered: a moderate rise of task-oriented categories was accompanied by a steeper rise of affective and regulatory ones (negative emotion ×4.4, confrontation ×3.6). The severity score correlated with most categories. The dependence of speech volume on load level was non-linear — with a rise, a plateau and a paradoxical decline at critical intensity.Limitations. The study has a number of limitations. First, only the crew’s external communication with ground services is available for analysis; intra group communication was not recorded for bioethical reasons, which, from the perspective of designing a scientific experiment, limits the reconstruction of a number of phenomena. Second, the interpretation of the relationship between categories in terms of locus of control requires further validation through direct psychodiagnostic measurements. Thirdly, inter category comparisons partially depend on the coding scheme. Fourthly, the sample is limited to 14 cosmonauts from the Russian segment, and subgroups of rare content types (in particular, psychological problems) are objectively rare and small in number, which requires caution when generalizing. Finally, the stress score is partially based on expert assessment, which means that the "expert problem" in this study has not yet been fully resolved. The listed limitations outline the directions for further work, including the validation of the scale and the application of the approach to other professional groups.Conclusion. The content of professional speech reflects both the degree and the substantive type of stress associated with the work and rest (W&R) schedule, and in this regard, it can serve as a non invasive indicator of acute situational stress and the preservation of the adaptive response of the human operator.Ethics. The study was conducted as part of the routine space experiment "Content" on the Russian segment of the International Space Station. All participants provided informed consent; the study was approved by the bioethics commission of the Institute of Biomedical Problems of the Russian Academy of Sciences and the Human Research Multilateral Review Board (protocol No. 14 006).Contributions:Yusupova A.K. — research concept and design, development of the problem severity scale, data collection and processing, statistical analysis, text writing;Supolkina N.S. — concept and design of the study, development of the problem severity scale, data collection and processing, editing.Acknowledgement. The authors express gratitude to A.P. Nechaev for his interest in the development of his valuable practical findings.Funding. Data collection and initial processing were carried out within the Framework of the RAS Fundamental Scientific Research Program FMFR-2024-0034, as well as within the Framework of the RAS Fundamental Scientific Research Program FMFR-2024-0038. The data analysis was carried out with funding from the State Corporation "Roscosmos".Conflict of interest. The authors declare no conflict of interest.Received: 22.09.2026 / Accepted: 29.09.2026 / Published: 09.10.2026