Eighteen hearing-impaired subjects participated in the present study. The purpose was to investigate one general question: The nature of the relationship between verbal ability and speechreading. Verbal ability was assessed by two types of measure: a test of vocabulary size, and four tests of lexical access speed. The results demonstrated that lexical access speed was related to speechreading performance. Vocabulary size was not found to be directly related to the speechreading criterion; rather, its influence was in an indirect fashion via its relation to lexical access speed. It was concluded that lexical access speed could be used as a diagnostic tool, such that when an individual demonstrates lexical access that is unreasonably slow, it could be taken as an indication to suggest that rehabilitation programs should emphasize alternatives to speechreading. A general implication of the present results is that absence of relation between a predictor variable and the speechreading criterion does not necessarily imply absence of relation between the two. There is still a possibility that the predictor variable might be indirectly related to the speechreading criterion.
