Stimulus-based lexical distinctiveness as a general word-recognition mechanism.

Word recognition is generally assumed to be achieved via competition in the mental lexicon between phonetically similar word forms. However, this process has so far been examined only in the context of auditory phonetic similarity. In the present study, we investigated whether the influence of word-form similarity on word recognition holds in the visual modality and with the patterns of visual phonetic similarity. Deaf and hearing participants identified isolated spoken words presented visually on a video monitor. On the basis of computational modeling of the lexicon from visual confusion matrices of visual speech syllables, words were chosen to vary in visual phonetic distinctiveness, ranging from visually unambiguous (lexical equivalence class [LEC] size of 1) to highly confusable (LEC size greater than 10). Identification accuracy was found to be highly related to the word LEC size and frequency of occurrence in English. Deaf and hearing participants did not differ in their sensitivity to word LEC size and frequency. The results indicate that visual spoken word recognition shows strong similarities with its auditory counterpart in that the same dependencies on lexical similarity and word frequency are found to influence visual speech recognition accuracy. In particular, the results suggest that stimulus-based lexical distinctiveness is a valid construct to describe the underlying machinery of both visual and auditory spoken word recognition.