Because information theory equates information with event occurrence probabilities, when applying its methods, language researchers typically take the information provided by words to be their relative frequencies in a corpus. This implicitly assumes words occur uniformly across contexts, however empirically, word distributions are bursty: the likelihood of most words appearing in most contexts is small, whereas the likelihood of a word recurring in context is much higher. In an elicitation study we examined whether speakers are sensitive to the dynamic word occurrence probabilities this implies. Consistent with proposals that prenominal adjectives increase noun predictability, participants produced numerous seemingly redundant adjectives prior to unambiguous nouns at first mention. However, despite receiving no feedback, they produced significantly fewer adjectives before subsequent mentions of the same nouns, indicating they had re-evaluated their probabilities. These results support the idea that prenominal adjectives facilitate efficient communication, and that speakers' representations of lexical probabilities are dynamic.