Bidirectional Transformer Representations of (Spanish) Ambiguous Words in Context: A New Lexical Resource and Empirical Analysis

Lexical ambiguity -- where a single wordform takes on distinct, context-dependent meanings -- serves as a useful tool to compare across different LLMs' (LLMs') ability to form distinct, contextualized representations of the same stimulus. Few studies have systematically compared LLMs' contextualized word embeddings for languages beyond English. Here, we evaluate multiple bidirectional transformers' (BERTs') semantic representations of Spanish ambiguous nouns in context. We develop a novel dataset of minimal-pair sentences evoking the same or different sense for a target ambiguous noun. In a pre-registered study, we collect contextualized human relatedness judgments for each sentence pair. We find that various BERT-based LLMs' contextualized semantic representations capture some variance in human judgments but fall short of the human benchmark, and for Spanish -- unlike English -- model scale is uncorrelated with performance. We also identify stereotyped trajectories of target noun disambiguation as a proportion of traversal through a given LLM family's architecture, which we partially replicate in English. We contribute (1) a dataset of controlled, Spanish sentence stimuli with human relatedness norms, and (2) to our evolving understanding of the impact that LLM specification (architectures, training protocols) exerts on contextualized embeddings.