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.

翻译：隐喻是文学语言的显著特征，但其在实验研究方面仍不及日常隐喻深入。此外，尽管许多文学隐喻的创造年代与当代读者相隔数个世纪，以往的心理语言学和计算研究方法却忽视了时间维度。本研究创新性地运用历时分布语义学工具，评估文学隐喻的处理成本是否随时代和体裁而变化。具体而言，我们在19世纪和21世纪的意大利文学与非文学语料库（共计1.24亿词符）上训练词嵌入模型，并对515个19世纪文学隐喻的"主题"与"载体"之间的语义相似度变化进行建模，以此作为隐喻处理需求的代理指标。总体而言，语义相似度（即隐喻处理需求）随时间推移保持稳定。然而，体裁因素起着关键作用：与现代文学语境相比，19世纪文学中的隐喻表现出更高的处理难度（即主题-载体相似度较低）；而与19世纪非文学文本相比，当代非文学语言（如网络用语）中的隐喻处理难度更低（即主题-载体相似度较高）。这一模式进一步受到隐喻各成分语义特征的影响，例如向量一致性和语义邻域密度。综合来看，这些发现与意大利语更广泛的语言变迁相吻合：现代文学的文体简化可能增加了隐喻处理需求，而网络语言的高创造性则似乎使隐喻更易理解。