Incidence and Impact of Missing Functional Elements on Information Comprehension using Audio and Text.

Audio is increasingly used to communicate health information. Initial evaluations have shown it to be an effective means with many features that can be optimized. This study focuses on missing functional elements: words that relate concepts in a sentence but are often excluded for brevity. They are not easily recognizable without linguistics expertise but can be detected algorithmically. Two studies showed that they are common and affect comprehension. A corpus statistics study with medical (Cochrane sentences, N=44,488) and general text (English and Simple English Wikipedia sentences, N=318,056 each) showed that functional elements were missing in 20-30% of sentences. A user study with Cochrane (N=50) and Wikipedia (N=50) paragraphs in text and audio format showed that more missing functional elements increased perceived difficulty of reading text, with the effect less pronounced with audio, and increased actual difficulty of both written and audio information with less information recalled with more missing elements.