Metaphors' journeys across time and genre: tracking the evolution of literary metaphors with temporal embeddings

TL;DR

This study examines how the processing of literary metaphors in Italian has evolved over time and across genres using diachronic distributional semantics, revealing stable semantic similarity but genre-dependent processing difficulty.

Contribution

It introduces a novel diachronic embedding approach to analyze the temporal and genre-based evolution of literary metaphors, highlighting the influence of linguistic changes and digital language on metaphor processing.

Findings

Semantic similarity of metaphors remained stable over time.

Metaphors are more difficult in modern literary contexts than in 19th-century literature.

Metaphors are easier in today's nonliterary language compared to 19th-century texts.

Abstract

Metaphors are a distinctive feature of literary language, yet they remain less studied experimentally than everyday metaphors. Moreover, previous psycholinguistic and computational approaches overlooked the temporal dimension, although many literary metaphors were coined centuries apart from contemporary readers. This study innovatively applies tools from diachronic distributional semantics to assess whether the processing costs of literary metaphors varied over time and genre. Specifically, we trained word embeddings on literary and nonliterary Italian corpora from the 19th and 21st centuries, for a total of 124 million tokens, and modeled changes in the semantic similarity between topics and vehicles of 515 19th-century literary metaphors, taking this measure as a proxy of metaphor processing demands. Overall, semantic similarity, and hence metaphor processing demands, remained stable over time. However, genre played a key role: metaphors appeared more difficult (i.e., lower topic-vehicle similarity) in modern literary contexts than in 19th-century literature, but easier (i.e., higher topic-vehicle similarity) in today's nonliterary language (e.g., the Web) than in 19th-century nonliterary texts. This pattern was further shaped by semantic features of metaphors' individual terms, such as vector coherence and semantic neighborhood density. Collectively, these findings align with broader linguistic changes in Italian, such as the stylistic simplification of modern literature, which may have increased metaphor processing demands, and the high creativity of the Web's language, which seems to render metaphor more accessible.