Beyond Surprisal: A Dual Metric Framework for Lexical Skill Acquisition in LLMs

AbstractMany studies have explored when and how LLMs learn to use specific words, primarily by examining their learning curves. While these curves capture a model’s capacity to use words correctly in context, they often neglect the equally important skill of avoiding incorrect usage. In this paper, we introduce a new metric, anti-surprisal, which measures a model’s capacity to refrain from using words in inappropriate or unexpected contexts. By examining both correct usage and error avoidance, we offer a more comprehensive perspective on the learning dynamics of LLMs.