Speaking Rationally: Uniform Information Density as an Optimal Strategy for Language Production

We provide evidence for a rational account of language production, Uniform Information Density (UID, Jaeger, 2006; Levy & Jaeger, 2007). Under the assumption that communication can usefully be understood as information transmission over a capacity-limited noisy channel, an optimal strategy in language production is to maintain a uniform rate of information transmission close to the channel capacity. This theory predicts that speakers will make strategic use of the flexibility allowed by their languages. Speakers should plan their utterances so that elements with high information are lengthened, and elements with low information are shortened, making the amount of information transmitted per time more uniform (and hence closer to the optimum). In three corpus studies, we show that American English speakers’ use of contractions (“you are” → “you’re”) follows the predictions of UID. We then explore further implications of UID for production planning.