Diachronic Analysis of Phrasal Verbs in English Scientific Writing (2025)

Abstract: Phrasal verbs (PVs) are a specific type of multi-word expressions and a specific feature of the English language. However, their usage in scientific prose is limited. Our study focuses on the analysis of phrasal verbs in the scientific domain using information theory methods to describe diachronic phenomena such as conventionalization and diversification regarding the usage of PVs. Thus, we analysed their developmental trajectory over time from the mid-17th century to the end of the 20th century by measuring the relative entropy (Kullback-Leibler divergence), predictability in context of the phrasal verbs particles (surprisal), and the paradigmatic variability using word embedding spaces. We were able to identify interesting phenomena such as the process of conventionalization over the 20th century and the peaks of diversification throughout the centuries.

## introduction multi-word expressions (mwes) are sequences composed of two or more words that have a degree of conventionality among speakers of the language community, holding a strong relationship in communicating meaning @xcite . mwes encompass idioms that are formally fixed and have a figurative meaning (e.g., kick the bucket), compounds (bus ticket), phrasal verbs (take a ride), and other formulaic expressions that are typically compositional and often lexically fairly productive (cf. @xcite ). mwes contribute to language efficiency due to the highly predictable transitions from one word to the next and/or because of their high degree of conventionalization (i.e., convergence in linguistic usage over time). also, mwes have a strong influence on register formation, providing conventional encodings of context-specific meanings. we are principally interested in mwes in scientific english from a diachronic perspective (mid-17th century to today). scientific english developed into a recognizable register during the late modern period and became highly conventionalized in modern times (cf. @xcite ). however, phrasal verbs (pvs), despite being a specific type of multi-word expression and one of the most distinctive features of the english language, are less common in academic prose, when compared to other registers. in the scientific register, usually more specialized verbs are preferred (cf. @xcite and @xcite ). the usage of pvs in english scientific writing indicates specific lexical choices influenced by contextual configurations and communicative constraints. thus, our aim is to investigate, using information theory measures, whether phrasal verbs contribute to standardization in scientific english as other types of mwes and grammatical constructions do. our idea is to analyse if the effects of conventionalization of phrasal verbs can be observed over time with three different approaches: 1) analysis of pvs temporal dynamics using relative entropy, 2) study of the predictability in the context of the pvs particles using surprisal measure, and 3) examination of the paradigmatic variability of pvs using embeddings. the remainder of the paper is organized as follows. in section 2 we discuss related work on pvs in scientific english. sections 3 and 4 present our methods and results, followed by a discussion of the main findings in section 5. we conclude with a summary and outlook (section 6). ## related work as previously mentioned, pvs are known for being less common in scientific texts when compared to other registers. @xcite shows that pvs are mostly used in speech and fiction. news texts tend to use less than these two genres, but academic prose is where pvs have the least overall frequency per million words. regarding diachronic analysis of pvs in scientific english, @xcite showed that compared to other types of mwes, pvs are the only ones presenting a decrease in its relative frequency over time (mid-17th century to end of 20th century). moreover, pvs present a specific behaviour regarding dispersion and association measures. in terms of dispersion, most pvs are not homogeneously distributed over time, only very specific ones commonly used in academic texts such as carried out, pointed out, and depend on. regarding the association measures, as the verbs and particles are also found in other contexts, in most cases, the values were quite low, except for specific cases where the verb is mostly used with its particle (e.g., churned up, smoothes out, budded off ). although the authors present a preliminary diachronic analysis of the evolution of the association measure, no conventionalization study was presented. the diachronic changes of the paradigmatic variability of different parts-of-speech in scientific english using word embedding space were analysed by @xcite . overall, there is a reduction of paradigmatic variability over time for the different grammatical classes. however, pvs were not analysed separately to see if their behaviour is similar or discrepant when compared to other verbs. moreover, there are numerous corpus-based studies of mwes in different registers, including the scientific one (e.g. @xcite ; @xcite ; @xcite ). some of these descriptions include lists of mwes used in academic texts that are freely available as part of english for academic purposes (eap). however, since pvs are not commonly used in scientific texts, they are usually not considered in the analysis. regarding computational methods for identifying pvs, the parseme initative 1 clearly identifies pvs or verb-particle constructions (vpcs) as one category of verbal mwes. multilingual cor-1 https://gitlab.com/parseme/corpora/-/wikis/home pora annotated following parseme guidelines are available, however, without any diachronic data. finally, in terms of studies regarding the cognitive processing of pvs, most studies concern l2 learners and the difficulties of learning these specific mwes (cf. alejo-gonzález (2010); mohammed (2019); @xcite . in their study, @xcite looked at surprisal measures to analyse the effects in priming of phrasal verb construction alternations, comparing native speakers and l2 learners, thus, focusing on learning difficulties, not in conventionalization processes as this paper. ## discussion in this study, our main objective was to analyse the contribution of pvs regarding the conventionalization processes happening in scientific english. by analysing three different methods to measure linguistic shifts over time, we were able to notice that, although pvs are less common in scientific prose, they have undergone interesting diachronic phenomena. regarding the relative entropy measures (i.e., kld), it was possible to notice that a conventionalization process occurred only throughout the twentieth century (figure 2 ). from the seventeenth to the twentieth century, although some small peaks and troughs can be observed, the kld values did not change considerably. this tendency is different from what was observed by @xcite who analysed the whole lexicon (i.e., lemmas). in their study, the decreasing tendency is relatively constant throughout time. moreover, it was possible to verify that the conventionalization process occurs in parallel with a peak of diversification, as shown in figure 3 . this diversification has an impact on the surprisal measures, increasing the surprisal of the particles. both conventionalization and diversification processes are also confirmed with the paradigmatic variability analysis (figure 6 ). pvs undergo a more accentuated decrease in their paradigmatic variability over time when compared to other verbs, principally during the twentieth century. to better understand the peaks regarding the diversification of pvs, we analysed in detail the results of the kld for each pv, per 20-year slice, present in the rsc. what is possible to observe is that, throughout time, there are shifts regarding the pvs with peaks of kld, i.e., verbs becoming more distinctive of specific periods. regarding the two main peaks of diversification identified in figure 3 , around 1846 and 1971, we can see that the pvs with the highest values of kld in these periods differ considerably. a clear distinction can be made when analysing these two periods. in the nineteenth century, most pvs are linked to the description of experimental design, while in the twentieth century, there is a shift towards verbs focusing on the presentation of results, i.e., on the outcome of the research. in figure 3 , we showed that the diversification is cyclic, new phrasal verbs are used in specific periods due to particular textual needs and, then, become less typical in future ones, however, in a more conventionalized way throughout the twentieth century. regarding the surprisal analysis, it is possible to notice that the shifts in the surprisal of the particles are a complex phenomenon. it is influenced not only by the peaks regarding the diversification process, but also by the changes regarding the distance between the verb and the particle, and, by the decrease regarding the relative frequency (i.e., with the verbs and particles appearing in more varied contexts, not as phrasal verbs). ## conclusions and future work in this paper, we presented a multifaceted approach to characterize diachronic shifts regarding the usage of pvs in scientific english from the mid-seventeenth century to the end of the twentieth century by applying different information theory methods to the royal society corpus. by measuring the kullback-leibler divergence, we showed that the process of conventionalization of pvs occurred mostly throughout the twentieth century. moreover, we observed that peaks of diversification (i.e., increase in the number of pv types) happened in specific periods, followed by periods with a high number of pvs becoming less typical. in terms of surprisal measure regarding the particles, we identified an overall tendency of increase, however, it was also possible to notice periods of accentuated increase, and some periods of decrease. these phenomena are probably correlated to the decrease regarding the relative frequency, to the peaks of diversification, and, to the distance between the verb and particles. the analysis of the paradigmatic variability showed that pvs have a more accentuated decrease over time when compared to other verbs. this is probably due to the usage of pvs in specific contexts, where they cannot be replaced by similar terms. moreover, the highest decrease regarding this measure was observed during the twentieth century, when a conventionalization phenomenon was detected using kld. our findings not only enhance understanding of pvs in scientific english but also pave the way for future linguistic research, particularly in language evolution and specialized registers. in future work, we intend to proceed with the analysis by conducting a semantic analysis of the pvs with peaks of divergence to better understand their usage throughout time. moreover, as part of a larger study, these results will be integrated with other types of mwes (e.g., compounds, fixed expressions) to better understand the impact of the usage of these formulaic expressions in scientific texts throughout time.