Is Change the Only Constant? An Inquiry Into Diachronic Semantic Shifts in Italian and Spanish
Authors: Matteo Melis, Anastasiia Salova, Roberto Zamparelli (Università di Trento, 2023)
Topic: Lexical and Semantic Resources and Analysis

Abstract
An increasingly prevalent approach to studying the gradual change of word meanings over time involves using distributional semantics, which is based on neighboring words. This study combines methods from Hamilton et al. (2016) [1] and Uban et al. (2019) [2] to analyze deceptive cognate pairs in historical and contemporary Italian and Spanish corpora. By employing fastText word embeddings and various similarity measures, it aims to investigate the change of word meanings and test two laws of regularity proposed by Hamilton et al. (2016) [1], along with a new hypothesized regularity in language change regarding analogy. The findings show a coherent evolution of deceptive cognates across the two languages. However, no meaningful correlation is found regarding the two aforementioned laws. Nevertheless, the results of the hypothesized regularity offer valuable insight into how the context of word usage shifts along with the word.

Introduction
In recent years, there has been a growing interest in studying the shift of word meanings over time, with word embeddings emerging as a valuable tool for this purpose. Hamilton et al. (2016) [1] conducted research focusing on diachronic word embeddings to uncover specific statistical laws associated with semantic change. They examined the law of conformity, which suggests that words tend to change inversely to their frequency. Additionally, they explored the law of innovation, which proposes that words with greater polysemy tend to undergo semantic changes more frequently, regardless of how often they are used. The findings confirmed the hypothesized statistical laws. The study primarily focused on English, aligning word embeddings from different time periods and measuring semantic similarity using cosine similarity. Dubossarsky et al. (2017) [3] contested the validity of the reported laws of semantic change based on word representation models. Replicating previous studies, they found that the law of conformity and the law of innovation did not withstand the more rigorous standard. The negative correlation between word frequency and meaning change was weaker than previously claimed, and the positive correlation between polysemy and meaning change was largely dependent on word frequency without independent contribution. Similarly, to Hamilton et al. (2016) [1], Uban et al. (2019) [2] investigated semantic divergence across languages by examining deceptive cognate sets, which are words with a common origin in different languages. They focused on analyzing modern embeddings to quantify semantic shifts originating from shared etymology, identify false friends (deceptive cognates) in the cognate sets, and measure their score of falseness, namely the dissimilarity between the cognates. The study primarily concentrated on six Romance languages. The authors introduced methodologies such as aligning word embeddings across languages, measuring semantic similarity and divergence between cognate sets, and quantifying the magnitude of semantic changes. Their findings contradict those of Hamilton et al. (2016) [1], who found a negative correlation between frequency and meaning shift. However, they align with their findings regarding the law of innovation.

Conclusion
The hypothesized regularity regarding analogy, a follow-up analysis in this study, has provided intriguing insights into semantic shifts. However, it is important to note that further research into this topic is necessary to validate and expand upon these initial findings. On the other hand, the analyses conducted in this study do not yield definitive results supporting the statistical laws of semantic shifts. Firstly, the RSA evaluation of the embedding spaces revealed that the scarcity of data significantly impacted the quality of the embeddings. Furthermore, while the law of conformity agrees with previous literature in a general trend, such as Hamilton et al. (2016), our study identified a contrasting trend for the law of innovation. This discrepancy in findings may be attributed to the limitation of our study, namely the scarcity of data resulting from the use of relatively short time periods. An additional factor is the relatively short temporal distance between the historic (as recent as 1969) and the modern corpora. Increasing this span is likely to lead to greater shifts, but also to greater data sparsity. Last but not least, the alignment technique employed for matching the embedding spaces could have contributed to the divergent outcomes in the analysis of the law of conformity and the law of innovation. It is noteworthy that both the laws of conformity and the law of innovation conform to the findings of Dubossarsky et al. (2017). Their study revealed that the suggested positive correlation between meaning change and polysemy was primarily influenced by word frequency, and the correlation between word frequency and meaning change is indeed weaker. Here, after conducting partial correlation analysis, a weak correlation was observed. Furthermore, we noticed a high compatibility between frequency and polysemy, indicating an inherent dependence, despite our efforts to disentangle them using partial correlation. Utilizing the fastText model, known for its improved performance on non-English languages, and preprocessing freely available data, the results still highlight poor quality embeddings. This underscores the need for ongoing research and development of word embedding models, alongside the creation of larger, well-curated diachronic corpora. Improving data quality and quantity can enhance the accuracy and reliability of future studies in the field. It is important to note that due to the limitations of the embeddings used in this study, the shifts observed in the inter-language Jaccard distance analysis are relatively small and close to each other. This leads to an extremely high correlation coefficient between the languages being analyzed, which should be interpreted with caution. In addition to the aforementioned directions, other potential areas of research include expanding further in time and broader in the scope of languages. For instance, this could involve going beyond the Romance or even the Indo-European language family to conduct a more comprehensive investigation into language change.