On the visual distinctiveness of words in the English lexicon

Abstract

Speechreading (lipreading) should be facilitated when spoken words are visually distinct. It has been established that the English lexicon has a high degree of visual distinctiveness: most words remain visually unique even when distinctions are collapsed across phoneme classes, as is characteristic of visually-perceived (i.e., speechread) speech. We asked, is the high degree of visual uniqueness in English a distinctive, nonaccidental property of the lexicon? Perhaps not: the lexical space of English (number of possible words, given some limit on the number of syllables per word) is large. That is, many lexical slots exist; a fairly low percentage are filled with actual words. Given this, the visual distinctiveness of the English lexicon may derive from the segment inventory and phonotactics of the language, rather than being a property of the lexicon per se. In this study, we compared the visual similarity properties of words in simulated, English-like lexicons to the visual similarity properties of words in an actual English lexicon. Each novel lexicon was generated on the basis of the phonotactic patterns of the actual English lexicon. The results indicate that a high degree of visual distinctiveness is an expected property of the lexicon, given the segment inventory and the phonotactics of the language.