Information density of speech: Languages differ in time per degree-of-freedom in picture description tasks

Using simple two-object picture description tasks, we studied the differences in the speed of information transmission across five languages. All speakers showed strong linear dependences between the number of degrees-of-freedom (DOF) and speech time. The amount of time per DOF was much shorter for Mandarin Chinese as compared to the other four languages (English, Russian, Vietnamese, and Korean). The Korean speakers spent more time per DOF compared to other languages. We discuss the results as possible consequences of the language morphology. In a pilot study, speech time was analyzed during descriptions of cartoons from “The New Yorker”. DOFs were estimated by two experimenters independently. Speech time increased linear with DOFs but at about half the rate as compared to the two-object tasks. We conclude that, while the general increase in ST with DOF is valid over a broad range of picture description tasks, less constraining tasks may show faster speech.